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Chapter 3
REPRODUCTIVE BIOLOGY
3.1 INTRODUCTION
The reproductive biology of crustaceans is a subject that has derived
much attention over centuries. Reproduction and breeding cycles of
crustaceans have been described by Rahman (1967), Ryan (1967),
Haefner (1976) and Zuckner (1978). Pochon-Masson (1983) and Adiyodi
(1985) described the process of spermatogenesis while oogenesis has
been described by Raven (1961), Norrevang (1968) and Adiyodi and
Subramaniom (1983). The effects of hormones on moulting and
reproduction have been described by Passano (1960), Adiyodi and
Adiyodi (1970), Nagabushanam et. ai, (1980), Quackenbush (1986) and
Fingerman (1987). A lot of information on the reproductive biology and
behaviour of lobsters, particularly palinurid and homarid lobsters, has
been documented over the last five decades. Several studies have
been made on fished populations of lobsters. Studies on reproduction in
Jasus lalandii by Fielder (1964) and Heydorn (1965), on fecundity in
Panulirus longipes by Morgan (1972), on the comparison of
spermatophoric masses and mechanisms of fertilization in the Southern
African spiny lobsters by Berry and Heydorn (1970), on the biology of
P. homarus by Berry (1971), on Palinurus gilchrisli by Pollock and
Augustyn (1982) and Jasus edwardsii and J. tristani by Pollock and
Goosen (1991) are some of the most important early studies which
provide primary insight into this complicated biological process. Mac
14
Diarmid (1987) and Mac Diarmid et al. (1991) studied reproductive
patterns and behavior in a population of J. la/andii in a protected
reserve in northern New Zealand. Mac Diarmid (1987) demonstrated the
impact of male aggressive behavior on the selection of males by female
lobsters. Several field studies of tropical spiny lobsters indicate that rapid and
repetitive brood cycles are common, upto five broods per annum (Briones
Fourzan and Lozano-Alvarez, 1992; Junio, 1987; Mac Diarmid, 1987).
Nelson ef a/., (1988a, b, c) and Waddy and Aiken (1992) monitored the effects
of environmental variables on gonadal maturation in female lobsters and
stressed the importance of monitoring the effects of environmental
variables on gonadal maturation in female lobsters. Junio (1987) carried
out an extensive study of P. penicillafus (Oliver, 1791) in the Philippines.
Lyons ef a/., (1981) summarized the reproductive biology of the Florida
spiny lobster P. argus in populations under light, heavy and no fishing
pressure. Lipcius (1985) and Hernnkind and Lipcius (1989) also studied
reproductive behaviour in P. argus. Briones - Fourzan and Lozano
Alvarez (1992) studied two populations of closely related palinurids - P.
inflafus and P. gracilis. Quackenbush and Herrnkind (1983) and Lipcius
and Herrnkind (1987) studied the effects of photoperiod on the moult
cycle and reproductive behaviour in P. argus. Gomez et al. (1994)
determined the breeding period of P. longipes longipes in the Philippines
by studying ovarian development and egg-bearing in the fished
population of females. George (1965) has recorded the breeding season
of P. homarus along the south-west coast of India. The maturation cycle
in female P. japonicus has been described in detail by Nakamura (1990) and
15
Minagawa and Sano (1997). Radha and Subramaniom (1985, 1987)
described spermatophore formation in P. homarus. Hussain and Amjad
(1980) have studied the breeding and fecundity of P. polyphagus along
the Pakistan coast. Kagwade (1988a, b) has described reproduction and
fecundity in P. polyphagus from Maharashtra waters.
Several studies on the histological structure and development of the
gonads have been carried out, particularly in palinurid lobsters (Fielder, 1964;
Berry and Heydorn, 1970; Radha and Subramoniam, 1985; Nakamura, 1990;
Minagawa and Sano, 1997 ) and homarid lobsters (Schade and Shivers,
1980; Marcia and Talbot, 1982).
In comparison with spiny lobsters, there is very little information
on the biology and reproductive behaviour of scyllarid lobsters. Fecundity
and spawning seasons have been studied in the Mediterranean Locust
Lobster, Scyl/arides latus (cf. Martins, 1985) and the slipper lobster, S.
nodifer, from the northeastern Gulf of Mexico (Lyons, 1970; Hardwick and
Cline, 1990). In Australia, there has been relatively more documentation
on the reproductive characteristics of T. orientalis (Kneipp, 1974;
Hossain, 1978a, b, 1979; Branford, 1980; Jones, 1988) Stewart et al.,
(1997) have described the size at first maturity and reproductive biology
of Ibacus peronii and Ibacus sp. from Australian waters. Stewart and
Kennelly (1997) have described the fecundity and egg size in I. peronii.
DeMartini and Williams (2001) studied fecundity and egg size in Scyl/arides
squammosus. DeMartini et al. (2005) discussed indicators of sexual maturity
16
in S. squammosus and the spiny lobster P. marginatus. Kagwade and Kabli
(1996) recorded the breeding peaks, fecundity and size at first maturity of
T. orienta/is from the Mumbai coast. Rahman et al. (1987) studied the
egg development in T. orienta/is. Moulting in female T. orienta/is has
been described by Rahman and Subramaniom (1989).
There is not much information on the reproductive biology and
behaviour of P. po/yphagus or T. orienta/is held in captivity. In the present
study, an assessment of the reproductive biology of the two species has
been made through -
• Morphological and histological observations on gonadal structure and
development in lobsters collected from the wild
• Observations on maturation-associated changes in secondary sexual
characters in lobsters collected from the wild and in lobsters held in
captivity
• Observations on mating and spawning behaviour in captivity
• Estimates of Gonadosomatic Index and fecundity in lobsters collected
from the wild
• Estimates of size at maturity in lobsters collected from the wild and in
lobsters held in captivity
Studies on reproductive biology of commercially important lobsters are
ultimately aimed at conservation and management of the resource in their
natural habitat and improving their aquaculture potential. Prediction of
minimum size limits to be observed for protecting spawning populations from
17
being destroyed by fishing activities and awareness of spawning seasons are
direct outcomes of such studies. Any information derived from observations of
reproductive biology and behaviour in captivity will be of use in developing
husbandry practices for the species and thus improve its candidature for
aquaculture. Successful captive propagation has the added advantage of
improving the status of natural stocks through sea ranching.
With growing impetus on establishing lobster aquaculture in India,
studies on reproductive biology and behaviour in the major lobster species
available in Indian waters assumes great significance.
3.2 MATERIALS AND METHODS
All animals for the study were collected from the trawl landings at
Veraval and Mangrol fish landing centres. Decline in catches, high cost and
high export demand for the lobsters greatly restricted the number of animals
available for the study. However, care was taken to ensure that animals
collected represented different size groups and stages of maturity. Animals
obtained live were maintained in the holding systems described in Chapter 2.
3.2.1 Sexual Dimorphism and Secondary Sexual Characters
Descriptions of external morphology for sexual dirnorphism and
secondary sexual characteristics were made from observations on 261 males
and 289 females of P. po/yphagus (35 - 110 mm CL) and 350 males and 221
females of T. orienta/is (35 - 100 mm CL) collected from the wild.
Morphological descriptions were made using standard lobster terminology
18
following Holthuis (1991). Structural variations in different body parts were
studied through direct observation and observation under a stereozoom
trinocular microscope (Carl Zeiss Stemi-2000).
3.2.2 Reproductive System - Structure and Development
Male and female reproductive systems of P. po/yphagus and T.
orienta/is were studied anatomically using 10 animals of either sex in each
species. Animals in the size range of 35 - 90 mm CL were chosen, so as to
get sufficient representation of different maturity stages. Gonadal maturation
was assessed primarily from the anatomy and appearance of the gonads.
Classification of ovarian developmental stages was done through descriptive
macroscopic staging following the methods of Fielder (1964), Jones (1988)
and Nakamura (1990). Testes were described in terms of their size, shape
and colour (Stewart et a/., 1997). Gonadal smears, eggs and spermatophores
were observed under a stereozoom trinocular microscope (Carl Zeiss Stemi-
2000).
Histological observations on gonadal maturity were made from
immature, maturing and mature gonads of male and female P. po/yphagus
and T. orienta/is. The colour and condition of the fresh gonads were
noted and the wet weights were measured to the nearest 0.1 g after
drying the ovaries with blotting paper. The gonads were then preserved
in 10% formalin and kept for standard histological processing. Dissections
were done in crustacean saline between 16:00 - 18:00 hours (to avoid
interference of circadian rhythms in the maturation process). The tissues
19
fixed in Aqueous Bouin's Fixative (ABF) for 24 hours, were treated
through tap water, graded series of tertiary butyl alcohol and
chloroform, before impregnation and embedding in paraffin wax.
Transverse sections of 6 - 8 11 thickness cut from the blocks were spread
on albumen-coated slides, stained in Harris's Haematoxylin and spirit
soluble Eosin, cleared in xylene and mounted in DPX.
Photomicrographs taken with a Canon digital camera attached to a trinocular
dissection microscope (Carl-Zeiss Axiostar) were used to study the
histological variations with maturation.
3.2.3 Mating and Spawning
Observations on mating behaviour, copulation, impregnation,
spawning, incubation and hatching were made on animals maintained live in
the laboratory. 1 tonne FRP tanks holding 900 I of seawater and covered
with light screens were used as brood stock development tanks for P.
po/yphagus. These tanks were operated on a Closed Recirculatory System,
using external biofilters. The tanks used for T. orienta/is were 400 litre FRP
tanks with in situ substrate (fine sea sand) bedfilter. Water temperature was
maintained in the range of 27 - 30'C, water salinity was maintained between
36 and 37 ppt and water pH was maintained between 7.8 and 8.0. Uniform
aeration was provided with a twin lobe air blower. Light exposure was kept
to a minimum. Water quality was monitored daily and water exchange was
carried out @ 30% daily. The animals were fed ad. libitum With fresh meat of
the gastropod, Turbo sp. The tanks were provided with shelters and hiding
20
places and care was taken to keep handling and environmental stress to a
minimum.
Four sets of broodstock development tanks were maintained for either
species. Juveniles of P. polyphagus were raised from 35 mm CL to 80 mm CL
in 250 days. Stocking was done @ 1 male per 3 females and 8 animals were
stocked in each tank. Juveniles of T. orientalis were raised from 30 - 40 mm
CL to 85 mm CL in 180 days. Stocking was done @ 6 animals per tank. The
sex ratio was kept at 1 male for two females.
Unilateral eyestalk ablation was done in early intermoult female P.
polyphagus in which decalcified windows on the fourth ventral sternite had
developed. 18 females were ablated and stocked with males which were used
for the first set of breeding experiments.
3.2.4 Gonadosomatic Index
The Gonadosomatic Index (GSI) was calculated using the formula as
given by Minagawa and Sana (1997) -
where,
1= GSI W = weight of gonad (g) L 3 = carapace length (mm)
The GSI values for individual lobsters were used to arrive at the average GSI
for different size groups (CL, mm) in different stages of maturity.
21
3.2.5 Size at sexual maturity
The size at sexual maturity was assessed from observations on 261
males and 289 females of P. po/yphagus (35 - 110 mm el) and 350 males
and 221 females of T. orienta/is (35 - 100 mm el) collected from the wild and
38 males and 43 females of P. po/yphagus (35 - 110 mm el) and 41 males
and 64 females of T. orienta/is (35 - 100 mm el) held in captivity.
The size at first maturity in both species was estimated by assessing
the size at which the animals become morphologically, physiologically and
functionally mature. The size at physiological maturity was assessed from the
condition of the gonad and its stage of development, based on the colour and
structure of the gonad. Histological observations were also done
simultaneously to ratify the developmental phase judged from the anatomy of
the gonads. All animals in an advanced state of gonadal maturation, those
that had mature or ripe gonads and those that were in a state of rematuration
were collectively grouped as "mature" while immature animals and those in
which gonadal maturation had just begun were grouped as "immature". The
frequency distribution of "immature" and "mature" lobsters, sex-wise, in the
sampled population was analysed, and the size at first (physiological) maturity
was read as the size at which 50% of the lobsters were "mature".
The size at morphological maturity was assessed similarly by following
the development of external indices of maturity like ovigerous setae in
females of both species and changes in the growth of the last three pairs of
pereiopods (walking legs), the ventral sternite length and the maximum width
22
of the carapace relative to carapace length in males and females of both
species. Changes in the length of the penile process in relation to the
carapace length was also studied in male P. po/yphagus. Linear plots of the
somatic lengths against the carapace lengths in size groups <50 mm CL and
> 50 mm CL were used to assess changes in growth patterns from juvenile
phase to sub-adult and adult phases. Comparisons were also made between
growth patterns of males and females of the same species. The sizes at
which deflections (if any) in regression lines between juveniles and sub-adults
or between males and females were studied for indications of the onset of
sexual maturity.
The size at functional or physical maturity was assessed from the
frequency distribution of males and females of either species with respect to
specialised structures which ensure the mating and propagative capabilities of
the animals -
• the formation of decalcified mating windows on the ventral side and the
formation of egg brush on the dactylii of the fifth pair of walking legs in
female P. po/yphagus
• the development and pigmentation of the penile process in male P.
po/yphagus
• the distribution of ovigerous condition in females of both species
3.2.6 Fecundity
Fecundity estimates were made from 47 egg batches (berried
females in the size range of 64 - 119 mm CL in P. po/yphagus and 53 egg
23
batches in the size range of 60 - 102 mm CL in T. orienta/is. The berried
animals were collected from the trawl landings at Veraval and Mangrol fish
landing centres.
The berries (egg masses) were oven dried and cleaned of
adhering material like setae, pleopods etc. The total dry weight (to the
nearest O.Olg) was measured using an electronic balance. The average
number of eggs in three 0.1 g sub-samples was raised to the total dry
weight of the berry to obtain the total number of eggs in that batch.
The relationship between fecundity and carapace length was estimated
by linear regression.
3.3 RESULTS
3.3.1 Sexual Dimorphism and Secondary Sexual Characters
3.3.1.1 Sexual dimorphism
Both P. polypl1agus and T. orienta/is exhibit sexual dimorphism. In
both species, there was considerable size difference between the sexes.
However, in P. polypl1agus, males were larger than their female counterparts
while in T. orientalis, the females were larger than the males. In both species,
the abdomen is considerably narrower in males than in females.
The males and females of either species can be easily identified
by the distinct morphological characteristics. which are summarized in the
following tables -
3.3.1.1A P. po/yphagus
Male
,. Genital opening (gonopore) on
coxa of fifth pair of walking
legs (PI. VII)
,. Gonopore is a complex structure
in the form of a penile process
(PI. VII; Fig. 4c)
,. Dactylus of fifth pereiopod
normal, as in other pereiopods
(PI. VI b; Fig. 4a: b)
j;o Dactylus of fifth pereiopods with
two rows of setae (PI. VI e)
,. Paired pleopods comparatively
small. Endopods vestigeal.
Exopods smaller than in female
24
Female
,. Genital opening (gonopore) on coxa
of third pair of walking legs
,. Gonopore is a simple aperture
,. Dactylus small and curved and
articulates with the small fixed claw
attached to posterior tip of propodus
of fifth pereiopod. (PI. VI a,c; Fig. 4a
a)
r Dactylus of fifth pereiopod with two
rows of longer, dense setae used as
egg brushes during incubation (PI. VI
d)
r Pleopods much larger; pleopodal
endopods of mature females bear
ovigerous setae (PI. VI g; Fig. 4b)
3.3.1.18 T. orientalis
Male
,.. Genital opening on coxa of
fifth pair of pereiopods (PI. X a;
Fig. 6a: b:vi)
r Gonopore is a relatively big
simple aperture (PI. X b)
r Dactylus of fifth pereiopods
bluntly cylindrical and club-
shaped. relatively slender and
sparsely setose. It ends with a
very small inwardly curved spine
(PI. IX c)
:;.. Pleopods comparatively small
(PI. IX d)
3.3.1.2 Secondary sexual characters
3.3.1.2A P. po/yphagus
3.3.1.2.Ai Male
25
Female
,.. Genital opening on coxa of third
pair of pereiopods (PI. X c; Fig. 6a:
avi)
,.. Gonopore is a simple aperture but
much smaller than the gonopore of
males (PI. X d)
,.. Dactylus of fifth pereiopods bluntly
cylindrical, more stout, with a
longitudinal groove on the dorsalr side
against which lies the claw. Dense
setae seen in maturing and mature
females (PI. IX c)
:;.. Pleopods much larger; pleopodal
endopods of mature females bear
ovigerous setae (PI. IX f-g; Fig. 6b)
(a) Pereiopods: (PI. VI b,e; Fig. 4a) The II - V pairs of pereiopods grow
relatively longer in the males as the animals approach sexual maturity. These
legs play an important role in holding the female at the time of courting and
mating.
26
(b) Gonopore and Penile Process: (PI. VII; Fig. 4c) The gonopore at the
end of the ejaculatory duct, on the coxa of the fifth pair of pereiopods, is a
complex structure associated with a pointed and serrated penile process
terminating in a distal tuft of setae. In juvenile male P. po/yphagus, the
gonopores are visible as tiny openings on the coxa of the fifth pair of
pereiopods. As the animal grows, a small knob-like protrusion develops on the
lateral edges of the coxa of the leg. As the animal approaches sexual
maturity, this structure becomes a prominent pointed penile process with a
curved tip bearing a tuft of setae.
The active gonopore in a mature male is membranous, with very strong
elastic folds and is highly sensitive. The pigmentation on the gonopore is also
an indicator of sexual maturity. While the gonopore is translucent white
initially, as the penile process develops, it develops a pinkish pigmentation,
often tending to reddish pink at the time of breeding (PI. VII c).
3,3,1,2.Aii Female
(a) Pereiopods and egg brush: (PI. VI a,c,d; Fig. 4a) The pereiopods in
females play an important role during incubation. The dactyli at the tip of the
pereiopods, particularly the fifth pair of pereiopods, develop long, dense setae
which are used as an egg brush, to clean the eggs carried on the abdominal
pleopods.
27
(b) Ovigerous setae on abdominal pleopods: (PI. VI f,g; Fig. 4b) The
endopods of the abdominal pleopods in females bear ovigerous setae which
are used for attaching spawned eggs until the end of the incubation period. In
juvenile female, the pleopods are devoid of setae. As the female enters into
the sub-adult phase, the pleopods enlarge and the endopods bifurcate and
develop long ovigerous setae. Development of the ovigerous setae marks the
onset of sexual maturity in females. Sometimes the setae are found to persist,
after two or three breeding cycles, even when the animals enter a non
breeding phase Therefore, while the setae may be indicators of sexual
maturity, they may not always be indicative of the breeding cycle of the
female.
(c) Mating window: (PI. VIII; Fig. 5) As the female enters its breeding
phase, a process of decalcification of the ventral sternal plates commences.
The plates at the base of the fifth, fourth and third pairs of pereiopods develop
soft mating windows which function as the sites of spermatophore deposition
during mating. There are four pairs of windows in p, polyphagus - two at the
base of the fifth ventral sternite and one each at the bases of the fourth and
third ventral sternites. The windows are separated by distinct calcified ridges.
Decalcification takes place from the base of the fifth pair of pereiopods to the
third, and the sizes of the windows increase with the size of the female.
3.3.1.2B T. orientalis
3.3.1.2Bi Male
28
(a) Gonopore: (PI.X a,b; Fig. 6a: b) The gonopore situated in the form of a
simple aperture at the base of the fifth walking leg, is seen to increase in size
as the animal grows.
There are no other distinct secondary sexual characters marking the
onset of sexual maturity in male T. orienta/is.
3.3.1.2.Bii Female
(a) Ovigerous setae on abdominal pleopods: (PI. IX e-g; PI XI; Fig. 6 b)
In T. orienta/is also, the endopods of the abdominal pleopods in females bear
ovigerous setae which are used for attaching spawned eggs until they are
hatched. In juvenile female, the pleopods are devoid of setae. As the female
enters into the sub-adult phase, the pleopods enlarge and the leaf-like
endopods bifurcate and develop long ovigerous setae. Development of the
ovigerous setae marks the onset of sexual maturity in females. There is a
small club-shaped process midway along the inner margin of the endopod of
the first pair of pleopods. The endopods of other three pairs of pleopods are
ovoid at the proximal end and narrow and tubular at the distal end.
(b) Gonopore: (PI. X c,d; Fig 6a: a:vi) The female gonopore, situated in
the form of a simple aperture at the base of the third walking leg, is seen to
increase in size as the animal grows but is relatively much smaller than the
male gonopore.
3.3.2 Reproductive System - Structure and Maturation
3.3.2.1 Reproductive system
3.3.2.1A P. po/yphagus
3.3.2.1Ai Male
(a) Anatomy
29
The male reproductive system (Plate XII; Fig. 7) in P. polyphagus
consists of paired testes and a pair of vas deferens leading to a narrow
ejaculatory duct. The testis is a semitransparent light yellowish organ placed
over the dorsal surface of the midgut gland, beneath the heart. The
mature testis is a H-shaped structure with two anterior lobes and two
posterior lobes. The anterior lobes extend to the gut and the posterior
lobes extend backwards up to the first abdominal segment. Paired vas
deferens arise from the outer side of the posterior lobes and open
through a chitinous sigmOid shaped gonopore on the coxopodites of the
fifth walking leg on either side. Each vas deferens arises as a slender
tube with a highly convoluted proximal end leading into a thicker and
dilated distal end which gradually thins down again to form the
ejaculatory duct. The thicker intermediate portion shows a tendency to
vary in size with the maturation process and contains a mucoid
substance. The proximal coiled region and the intermediate thicker
portion of the vas deferens are the sites of spermatophore production.
The spermatophoric mass (PI. XXI d-e; Fig. 11 f) consists of a highly
convoluted tube containing the sperm mass embedded in a gelatinous matrix
secreted by the inner lining of the proximal vas deferens. The outer covering
of the spermatophore is a layer of thick and hardened gelatinous material
30
secreted in the distal vas deferens. The spermatophores are retained in
the vas deferens until copulation. Following this, the spermatophores
are ejaculated through the ejaculatory duct at the distal portion of the
vas deferens.
(b) Histology of testis and vas deferens
(PI. XIII a-t; Fig 11 a-f)
The wall of the testis is double-layered, consisting of an outer
epithelium and an inner layer of connective tissue. At the onset of maturation,
the testis contains follicles or acini (seminiferous lobules) filled with primary
spermatophores (PI. XIII a-d). A lumen is formed in maturing testes and
development of the spermatids within the follicular cells is aided by the nurse
cells or Sertoli cells. The lumen is placed towards one side of the testis and
empties into the vas deferens.
Transverse sections of the vas deferens reveal a thin outer layer of
muscle and connective tissue and an inner layer of columnar epithelial cells,
enclosing the lumen (PI. XIII g-j). The epithelial cells are glandular in nature
and secrete a gelatinous matrix which is strongly eosinophilic. The sperm
mass, or spermatophore, consisting of spermatids, disintegrating
spermatocytes and Sertoli cells, is embedded in the mucoid matrix secreted
by the glandular epithelial cells. Within the spermatophore, the spermatocytes
and spermatids are embedded in a gelatinous substance. The sperm mass
moves through the lumen of the vas deferens from its proximal part to the
distal part. The glandular epithelium of the proximal vas deferens is folded
31
inwards. Proliferation and invagination of the glandular epithelium form leaf
like typhlosoles with villi in the distal vas deferens(PIXIlI k-r). The typhlosoles
secrete a strongly eosinophilic granular matrix into the lumen. The
spermatophore mass remains distinct within this matrix. At the time of
copulation, the spermatophoric mass is expelled from the vas deferens by the
muscular contraction of its walls.
3.3.2.1Aii Female
(a) Anatomy
The internal reproductive system of a mature female P.
po/yphagus is shown In PI XIV and Fig 8. The ovary is situated
dorsally, beneath the heart and over the midgut gland. The mature
ovary is H- shaped, with two anterior lobes extending into the cephalic
region and two posterior lobes extending up to the first abdominal
segment. The anterior lobes have curved tips, turning upwards. The two
posterior lobes are of unequal length, with the left lobe being slightly
longer. A pair of semi-transparent slender oviducts arising just below
the transverse connection between the two lobes open to the exterior
through a pore on the coxa of the third walking leg.
(b) Histology of ovary and oviduct
(PI XV a-I; Fig. 9)
The ovarian wall (PIXV h) consists of an outer epithelial layer, a
middle layer of connective tissue supplied with blood vessels and an
inner germinal epithelium. The thickness of the connective tissue
32
changes with the ovarian maturation cycle. The germinal epithelium
forms a series of inward folds as it runs through the length of the
ovary. Ova are formed from the germinal epithelium and are initially
surrounded by a single layer of flat follicular cells. Developed oogonia,
primary and secondary oocytes and developing ova can be seen distributed
from the central germinal epithelium to the peripheral wall of the ovary. The
process of ovarian maturation through oocyte formation and development was
traced through three distinct phases depending on the extent of yolk
deposition -
"y Pre-vitellogenesis phase: (PI. XV a-c) This is the immature phase in
ovarian development, where the outer wall of the ovary is thin. The
developing oocytes are mostly surrounded by follicle cells. The nuclei of the
developing oocytes are large and well-defined, with prominent nucleoli. There
is no indication of yolk deposition. The cytoplasm is basophilic and takes
haematoxylin stain.
"y Primary vitellogenesis phase: The ovary enters into the developing
stage, where the cytoplasm gradually becomes more eosinophilic. This
phase is completed through three stages.
Stage 1 : (PI.XV d) Many oocytes have a few peripheral vacuoles scattered in
the cytoplasm. The cytoplasm takes haematoxylin stain.
Stage 2 : (PI. XV e) There is an increase in the number of peripheral
vacuoles which tend to be distributed uniformly around the nucleus. Yolk
deposition begins in the cytoplasm of the developing oocytes. The cytoplasm
33
turns slightly eosinophilic. The germinal zone is placed centrally and
developing oocytes are seen near to the peripheral region.
Stage 3 The peripheral vacuoles are larger in size. Yolk deposition
becomes more dense. Eosinophilic granules increase in number among the
peripheral vacuoles. The egg membrane is seen between the oocyte
and the follicle cells.
:.- Secondary vitellogenesis phase The ovary is now in a mature
stage, where yolk granules accumulate abundantly in the developed
oocytes. This phase is completed in two stages -
Stage 1: (PI. XV f,i) Mature oocytes are seen in the ovarian cavity. Dense
yolk deposition takes place and nuclei begin to be masked. The cytoplasm is
highly eosin-positive.
Stage 2: (PI. XV g) The size of the oocytes become maximum while the
nuclei decrease greatly in size and can hardly be observed. Yolk deposition
is complete. The oocytes are now in a state of complete maturation. The
ovarian cavity is packed with mature oocytes.
The tubular oviduct (PI. XV j-I) is more compressed than round. The
wall of the oviduct is made up of an outer thin layer of epithelium, a middle
layer of connective tissue and an inner layer of high columnar epithelium. The
lumen of the oviduct in a mature adult is large and bears numerous long villi.
The columnar cells and villi often form semi-closed channels within the lumen
(PI. XV I)
3.3.2.1 B T. orientalis
3.3.2.1 Bi Male
(a) Anatomy
34
The testes (PI. XVI; Fig. 10), situated dorsal to the alimentary tract,
are a pair of highly convoluted white tubular structures joined by a
transverse bridge, giving it an H-shaped appearance. The lobes extend
backwards into the abdominal region. The vas deferens arise posterior
to the transverse bridge. The proximal vas deferens is highly
convoluted while the distal vas deferens is straight and opens through
the genital pore on the coxa of the fifth pair of pereiopods. The vas
deferens in a mature male holds the spermatophoric mass which is seen as a
white gelatinous substance. The spermatophoric mass is expelled from the
terminal tubular part of the vas deferens and through a pair of gonopores on
the coxa of the fifth pair of pereiopods at the time of copulation.
(b) Histology of testis and vas deferens
(PI. XVII a-I; Fig.11 g-h)
The wall of the testis is double-layered, consisting of an outer layer of
membrane and connective tissue and inner layer of epithelium (PI. XVII a-b).
The immature testis contains numerous follicle cells or acini filled with
spermatogonia (PI. XVII c-d). It is within these acini that the spermatogonia
develop into primary spermatocytes, secondary spermatocytes and
spermatids.
3S
Transverse sections of the vas deferens reveal an outer layer of
muscle and connective tissue and an inner layer of glandular epithelial cells,
enclosing the lumen. The spermatophoric mass, consisting of spermatids,
developing spermatocytes, disintegrating spermatocytes and nurse cells, is
embedded in a mucoid gelatinous matrix secreted by the glandular epithelial
cells. The sperm mass moves through the lumen of the vas deferens from its
proximal part to the distal part. The typhlosole (PI. XVII e-g) in the distal vas
deferens in T orienta/is is seen as one big lobe pushing inwards into the
lumen. The typhlosole has only connective tissue lacks villi and columnar
epithelium. The spermatophores (PI. XVII i) are seen arranged along the wall
opposite to the typhlosole, embedded in a gelatinous matrix (PI. XVII h).
Unlike in the case of P. po/yphagus, the final spermatophoric mass in T
orienta/is is not bound by a hardened gelatinous matrix.
3.3.2.1 Bii Female
(a) Anatomy
The ovaries (PI. XVIII & XIX; Fig. 12), like the testes, are a pair of
tubular structures connected by a transverse bridge, giving an H-shaped
appearance. The ovaries are also placed dorsal to the alimentary tract
A pair of thin oviducts arise from the ovary posterior to the transverse
ridge and open through the genital pores on the coxa of the third pair
of pereiopods.
-----------------_ .. _----
36
(b) Histology of ovary and oviduct
(PI. XX a-i)
The ovarian wall consists of an outer connective tissue supplied
with blood vessels and an inner germinal epithelium (PI. XX a-b). The
thickness of the connective tissue changes with the ovarian maturation
cycle, being thin initially and thickest in spenUrecovering ovaries. The
germinal epithelium (PI. XX d) tends to fold inwards and give rise to the ova.
Immature ova are surrounded by follicular cells. The ovary of immature and
maturing individuals lack a lumen; the ovaries of mature individuals were
found to have a central lumen. As in the case of P. po/yphagus, the process of
ovarian maturation in T orienta/is could also be traced through three distinct
phases depending on the extent of yolk deposition -
~ Pre-vitellogenesis phase: The ovary is in an immature state,
with a thin outer wall and immature oocytes. The oocytes have large and
well-defined nuclei and are mostly surrounded by follicle cells. There is no
yolk deposition. The cytoplasm is basophilic and takes haematoxylin stain.
).> Primary vitellogenesis phase The ovary begins developing.
Development of the oocytes progresses through two distinct stages -
Stage 1 : A number of developing oocytes are seen to have a few peripheral
vacuoles scattered in the cytoplasm. The cytoplasm takes haematoxylin
stain.
Stage 2 : (PI. XX c) As development progresses, there is an increase in the
number peripheral vacuoles which grow larger and tend to be distributed
37
uniformly around the nucleus. Yolk deposition begins in the cytoplasm of the
developing oocytes. The cytoplasm turns slightly eosinophilic .
., Secondary vitellogenesis phase In this phase yolk granules
accumulate abundantly in the developed oocytes and the ovary becomes
mature. Two distinct stages can be recognized in this phase -
Stage 1 : Dense yolk deposition takes place and nuclei begin to be masked.
The large vitellogenic oocytes are separated from the follicle cells by the
egg membrane. The cytoplasm takes eosin stain.
Stage 2: (PI. XX a,b,d) The oocytes are large, globular and non-nucleated or
with shrunken nuclei. Yolk deposition is maximum and dense yolk granules
are visible. The ovarian wall is strong and tense.
Transverse sections of a spent ovary reveal resorbed oocytes and
infiltration of connective tissue (PI XX e). The ovarian wall at this stage is
relaxed. Transverse sections of the oviduct reveal that the wall of the oviduct
is made up of an outer thin layer of epithelium, a middle layer of connective
tissue and an inner layer of columnar epithelium (PI. XX g-i). The tubular
oviduct (PI. XX f) in T. orienta/is is more compressed than round. Unlike in the
case of P. po/yphagus which has a large central lumen in the oviduct, the
lumen of the oviduct in T. orienta/is is smaller, as are the villi. The lumen is
placed towards the peripheral regions on either side of a central layer of
connective and muscular tissues.
3.3.2.2 Maturation
3.3.2.2A P. po/yphagus
3.3.2.2Ai Male
38
The testes in male P. po/yphagus do not show any visible colour
change during maturation (PI XII, Fig. 7) Immature gonads in juveniles
appear as translucent membranes and do not extend into the abdomen.
In sub-adults, the gonads become slightly whitish and the median vas
deferentia in males become opaque. The posterior lobes of the testes
do not reach upto the tip of the carapace at this stage. In adults, the
entire testis becomes milky-white, the distal vas deferens become very
thick (PI XII d) and the external gonopores in the form of penile processes
become pigmented (PI VII c & XII e). The posterior lobes of the testis now
extends beyond the carapace, into the abdomen. A mature male is always
characterized by the presence of spermatozoa in its testis.
Visible changes in the secondary sexual characters are a more reliable
means of assessing the status of sexual maturity. Development and
pigmentation of the penile process are positive indicators of the onset of
sexual maturity in males (PI. VII c & XII e; Fig. 4c).
3.3.2.2Aii Female
Ovaries that are immature ovaries or in the early stages of
development cannot be discerned visually through the dorso-thoracic
musculature. In the advanced stages of development, the ovaries are easily
39
viewed through the musculature. However, such visual assessment can be
misleading in the case of a spent ovary as the yellow colouration and onset of
rematuration can lead to identification as a developed ovary.
The ovary undergoes a series of colour and size variations in
tandem with the maturity cycle (Fig. 8). Immature ovaries in juveniles
appear as translucent membranes and do not extend into the abdomen.
In sub-adults, the ovaries become light yellowish and extend further
anteriorly and posteriorly. Mature ovaries are dark yellow or orange in colour.
The oviducts however, remain translucent. The posterior lobes of the
ovaries extend beyond the carapace, into the abdomen. A spent ovary is
usually light cream or light orange in colour and a number of residual and
resorbing ova are visible through the ovarian wall, lending a patchy
appearance to the ovary (PI. XIV).
Kagwade (1988) classified the ovarian cycle into seven stages. In
the present study the ovarian development was classified into five stages
- Immature, Developing/Redeveloping, Ripe, Spawned and Spent
Immature
Maturing
Thin, flattened,
transparent ova.
(Fig. 8a).
transparent ovary with
Nuclei are distinctly visible
Ovary slightly enlarged and white. There is
differential development of ova and small
transparent immature ova can be seen along
Ripe
Spawning
Spent/Recovery
40
with larger ones in which yolk deposition has
set in (Fig. 8b).
As development progresses, the colour
becomes orange and the ovary is enlarged,
with few transparent immature ova, opaque,
orange mature ova and a number of maturing ova
(Fig. 8c)
Dark orange fully ripe ovary with dark orange
opaque ova (Fig. 8d)
Orange ovary with white patches, retaining
part of the ova. Ova slightly smaller, orange
and opaque.
Flabby ovary white or light orange with
residual opaque ova and a number of
immature ova (PI. XIV).
The average diameter of freshly-laid eggs in P. polyphagus was 0.459
mm.
The onset of maturity in females is marked by the development of
ovigerous setae (PI. VI f-g; Fig. 4b) and decalcification of sternal plates (PI. VII
a-f; Fig. 5a-f). As the female matures, soft, decalcified windows appear on the
ventral sterna at the base of the third, fourth and fifth pairs of pereiopods.
These are the sites of spermatophore reception during copulation, and
storage until fertilization. The size of the windows increases as the female
grows and often the ridges of the sternal plates get rnerged with the windows.
3.3.2.2B T. orientalis
3.3.2.2Bi Male
41
As in the case of P. po/ypl7agus, there is no external indication of
gonadal maturation processes The testis and vas deferens undergo
alterations in size and form (Fig. 7). The colour tends to remain white, but as
maturation progresses, the gonads become less translucent and more
opaque. Immature gonads in juveniles of T. orienta/is also appear as
translucent membranes and do not extend into the abdomen. In sub
adults, the gonads become slightly whitish and the median vas deferens
become opaque (PI. XVI b). In active adults, the entire testis becomes
milky-white and the median vas deferens becomes very thick (PI. XVI c;
Fig. 10 c). The posterior lobes of the testis extend beyond the carapace,
into the abdomen (PI. XVI a).
The male gonopores, situated on the coxa of the fifth pair of
pereiopods are visible as tiny openings in juveniles, which grow larger in size
as the animals grows and enters sexual maturity. Unlike in the case of P.
po/ypl7agus, there is no distinct protrusion or extension of the gonopores into
penile processes and the gonopores exist as simple apertures (PI. X a-b; Fig.
6a: b).
3.3.2.2Bii Female
Ovarian maturation in T. orienta/is is similar to the process in P.
po/ypl7agus. The ovary undergoes a series of colour and size variations
in tandem with the maturity cycle. The immature ovary (PI. XIX a; Fig. 8a)
42
is translucent and becomes white as the animal enters into the early stages
of maturation (PI. XIX b-c; Fig. 8b). At this stage the posterior lobes of the
ovary do not extend into the abdominal region (PI.XVIII a). As maturation
progresses the ovary becomes creamish to dark yellow (PI.XIX d-e) and
finally dark orange, when it is ready for spawning (PI. XIX f). The oviducts
however, remain translucent. In the mature stage, the posterior lobes of the
ovary extend to the abdominal region (PI. XVIII b).
Kagwade and Kabli (1996) recognized five stages of ovarian
development in Torientalis. In the present study also the ovarian
development was classified into six stages - Immature, Early Maturing, Late
Maturing/Mature, Ripe, Spawning and Spent/Recovery.
Immature
Early Maturing
Late Maturing/Mature
The ovaries are initially seen as a pair of
translucent, white straight, thin structures. There is
no evidence of any individual oocytes (PI. XIX a).
Ovary becomes slightly enlarged and white.
Although individual oocytes are not visible initially,
as the ovary matures, small transparent immature
ova can be seen along with a few larger ones
in which yolk deposition has begun (PI. XIX b
c).
As development progresses, the colour
becomes orange and the ovary is slightly
enlarged with some transparent immature ova
Ripe
Spawning
Spent/Recovery
43
and opaque, orange maturing ova, which can be
seen through the ovarian wall. Towards the end of
this phase, the ovary is packed with mature ova
(PI. XIX d-e)
Dark orange fully ripe ovary with dark orange
opaque ova. The ovary occupies a major portion
of the cephalothoracic region and is easily visible
through the dorso-thoracic musculature (PI. XIX f).
Orange ovary with white patches, retaining
part of the ova. Ova slightly smaller, orange
and opaque (PI. XIX g).
Flabby ovary white or light orange with
residual opaque ova and a number of
immature ova.
The average diameter of freshly-laid eggs in T. orienta/is was 0.817 mm.
The onset of maturity in females is marked by the development of
ovigerous setae (PI. IX e-g; Fig. 6b). The setae, once developed, lose their
density after the first spate of egg bearing, but regains it during the next phase
of breeding. This continues as cyclic phenomenon, coinciding with the
breeding activity of the female. There are no mating windows in female T.
orienta/is.
3.3.3 Mating and spawning
3.3.3A P. po/yphagus
44
Mating in P. po/yphagus occurs 1 - 12 days prior to spawning (egg
release) and not immediately after the pre-mate moult. Fertilisation is external
and occurs only at the time of spawning. Mating is seen to be associated with
the development of orangish colour in the ventral sinus of the female,
indicating the presence of vitellogenin. The time between the pre-mate moult
and mating, during which the pre-copulatory courtship takes place, ranged
from 20 to 40 days.
Males exhibit aggressive behaviour among themselves and separate
dens should be provided for active males. Usually the largest male
monopolises the attention of all the females in one tank and a single male
successfully im pregnates upto four females. Reproductive success is
maximum between males and females of the same age group wherein the
males are larger than their female counterparts. Older males show poor
response to young females breeding for the first tirne. Males of 70 - 80 mm
CL were found to mate with females of 66 - 75 mm CL and males of 80 - 100
mm CL rnated with females of 75 - 95 rnrn CL. However, males of 100 - 120
mm CL did not show any response to reproductively active females of 66 - 75
mrn CL.
Courtship begins immediately after the female completes the pre-mate
rnoult. The reproductively active female performs stridulation to attract a
45
reproductively active male. Vision and antennal sensitivity also playa major
role in detection of a mating partner by the male. The male tracks the female,
usually from behind, continuously probing with the antennae. The male
chases the female continuously and feeding activity reduces considerably for
some days Courtship behaviour is best observed in the early evening hours.
The chasing activity continues during the day while mating occurs between
late night and early morning hours. There is no aggression between sexes
while mating.
Towards the final phase of courting, the male moves towards the
female and copulation takes place frontally as the male vertically embraces
the female, from head to tail. A diagrammatic representation of courting and
mating behaviour observed in P. po/yplJagus is given in Fig. 13 a.
The duration of copulation is very short and lasts for only two to three
minutes. The extensible cuticular membranes of the active male penile
process stretch and open outwards. As the male moves over the female, the
membranes of the gonopore stick on to the soft window areas on the sternum
at the bases of the fifth, fourth and third pereiopods of the females. The male
deposits the spermatophore along with its gelatinous matrix over the window
areas. Spermatophore extrusion is done continuously and it is deposited as
two layers, the outer layer being the gelatinous matrix which serves to cement
the spernatophore to the female plastron, and the inner core layer being the
convoluted spermatophore chambers. The implantation of the
46
spermatophores of the male lobster on the plastron of the female is
called impregnation and the spermatophore-bearing female is called an
impregnated female. As soon as impregnation is complete, the lobsters
separate immediately. There is no conspicuous post-mating co-habitation or
guarding of the females by the males.
The spermatophoric mass when freshly deposited on the female,
is white and soft. It soon darkens to a lichen-green colour and
becomes hard. It eventually turns blackish in colour, the pigmentation
proceeding inwards, from the margins. In this condition, it is also known
as the "tar spot". The tar spot is butterfly-shaped, broader at the base (over
the windows of the fifth walking leg) and tapering towards the top (over the
windows of the third walking leg) (PI. XXI a-c) It is quite smooth on the
outside and broader than reported in other spiny lobsters. The bigger the
male, the bigger is the spermatophore attachment.
The impregnated female now prepares itself for spawning, which
takes place 2 - 10 days after mating. Before egg extrusion, the female
scrapes the surface of the tar spot with the chelate part of the fifth leg
to release the sperms. The eggs from the oviduct pass over this sperm
mass and fertilization takes place in the brood chamber. It was observed
that in young females breeding for the first time, in 90% of the cases, the
spermatophore is almost completely scraped off and used up for fertilizing the
first batch of eggs, and only the margins of the attachment remain for a few
47
weeks on the sterna. However, in older females, a considerable part of the
spermatophore attachment is retained after the first egg extrusion. It remains
throughout the incubation period and is used to fertilize the successive batch
of eggs, unless it is tampered during frequent sampling and handling of the
female held in captivity.
The fertilized eggs attach themselves to the ovigerous setae on
the pleopods(PI XI, XXIII & XXIV b) This process is called oviposition.
Three pairs of dark scars mark the remnants of the spermatophoric
mass after it is completely scraped off (PI XXIII). Spawning in the
females is usually complete and the ovaries are very rarely seen to be
in a partially spent state. A mature female in the late intermoult stage
usually spawns twice, and sometimes thrice, during a single intermoult
phase, the gap between two a hatching and the next spawning ranging
from 2 to 5 days. Rematuration takes place after a span of about two
to three months, during which span the animals undergo atleast one
moulting. When mating fails to occur or impregnation does not take place
properly, the mature females release unfertilized eggs, which are pale
pink in colour. These eggs are shed from the pleopods in about two to
five days after spawning. Whenever mating occurs the eggs released
are fertilized and bright orange in colour (PI XXIV a). A single
impregnation usually suffices for two and sometimes even three
successive spawnings within the same maturation cycle of the female.
48
The incubation period in P. polyphagus ranges from 25 to 32 days and
is easily influenced by the water temperature. During this period, the females
maintain their lower abdomen and tail slightly bent inwards and the setose
exopods of pleopods and dactyli of the pereiopods are used to maintain
constant fanning and grooming of the eggs. The female tends to remain in
isolation and shows very little movement. Feed intake is also considerably
reduced during the incubation period.
At the time of hatching, the female straightens its abdomen and
extends the tip of the abdomen to the water surface, and the phyllosoma that
hatch out are fanned away with the pleopods. Hatching takes place only
during the early morning hours and is usually completed the same day. A
considerable number of eggs are prone to be lost during the incubation period
if water quality and tank bottom quality are not maintained well or if the animal
is subjected to increased handling stress.
3.3.38 T. orientalis
Males are smaller than females and are generally more active.
Courtship lasts for a few days prior to mating, when the males actively move
around in the tank often flipping over while swimming. During the courtship
period, the males are very active at night and are often seen swimming even
during the day, chasing the females, which are less active. Mating usually
takes place during late night hours.
49
There is no compulsory premate moult in this species. A female that is
ready to mate has well developed ovigerous setae and exhibits a colour
change in the ventral sinus. The male uses its antennules to sense the
presence of the female during the courtship chase, and as it catches up with
the female, it climbs on to the female and turns it over, holding on to its tail
end. Copulation takes place with the animals facing ventrally in reverse
position so that the ventral sternal tip of the male is slightly in front of the
female's sternum. Fig. 13 b provides a diagrammatic representation of the
courting and mating behaviour observed in T. orienta/is.
Copulation is slightly prolonged in this species, and lasts for nearly five
minutes. As the pair hold on to each other tightly with their legs, the female
probes the inter-tegumental membrane on the last abdominal segments of the
male and nibbles at its uropod. As a result, reproductively active males are
often seen with damaged uropod fans and tail ulcers which invite bacterial
invasion.
When copulation is over, the impregnated female curves its abdomen
inwards and holds it at a slight elevation from the tank bottom. It is not very
active and tends to crouch in some dark corner above the substratum. It
carries the impregnation till the early morning hours. The freshly released
spermatophores are milky white in colour, soft, delicate and embedded in a
gelatinous matrix of mucoid fibrils. The impregnation is seen on the ventral
side of the first abdominal segment as two parallel lines, usually extending
50
from the coxa of the fifth pair of pereiopods to the posterior tip of the second
abdominal segment (PI. XXII a-c). The spermatophore packets are ovoid in
shape and microscopic in size. They holding the active spermatozoa within.
The gelatinous matrix in which the spermatophores are embedded holds a
fibrillar network to which the spermatophores are attached (PI. XXII d-e).
When the spermatozoa are released for fertilization, the empty
spermatophore packets are left attached to the fibrils in the matrix (PI. XXII f).
Egg laying commences in about two hours and the eggs released are
guided from the sternal region to the abdominal brood chamber where they
are attached to the ovigerous setae on the endopod of the pleopods. The
abdomen remains completely curved inwards, forming a 'U'-shaped cup-like
brood chamber laterally sealed by the exopodites and the teeth-like
extensions of the abdominal tergites. The endopodal brances and their setae
spread like a floor on the ventral side of the chamber when all the eggs and
spermatozoa mixed with water have been pushed in.
Almost 90% of the eggs get attached to the pleopodal setae,
irrespective of whether they are fertilized or not. The fertilized eggs (PI. XXVI
a) are dark yellow or orange in colour while the unfertilized eggs turn pale
cream or pinkish. The unfertilized eggs are shed off in 3 - 5 days.
The incubation period in T. orienta/is ranges from 32 to 37 days, during
which embryonic development takes place inside the eggs (PI. XXVI c-f). The
51
abdomen continues to be curved inwards and the eggs are constantly fanned
with the exopods of the pleopods and cleaned with the setal brushes on the
dactyli of the pereiopods. Locomotor activity and feed intake are very much
reduced during the incubation period and the female tends to remain in
isolation.
At the time of hatching, the female holds the inwardly curved abdomen
at a slightly elevated angle and the phyllosoma that hatch out are fanned
away with the pleopods. Hatching (PI. XXVI g) takes place in batches only
during the early morning hours and 'IS usually completed in 1 - 3 days. After
hatching, the empty egg capsules are seen attached to the ovigerous setae.
The capsules are shed, along with a part of the setae, about 48 hours after
hatching. Water quality, tank bottom quality and handling stress, particularly
during the incubation period, greatly influence the success rate of hatching.
During the breeding period, the intermoult phase is highly extended in
the female. After the first brood of eggs have been hatched, the female begins
preparing itself internally for the next breeding, within the same intermoult
phase. Interestingly, the ovigerous setae that developed before the first
breeding continue intact for the next breeding also, in a single intermoult
phase. The entire process takes up to 150 days and in such periods, there is
a considerable delay in growth in these animals. I oj:;r 3 V
3.3.3.1
3.3.3.1A
Breeding in captivity
P. po/yphagus
52
In about 250 days of culture, males grew faster than females. All males
above 70 mm CL were sexually active, with well-developed penile processes
and pigmentation. Females above 66 - 70 mm CL, with full windows, became
active for breeding after a pre-mating moult Breeding success was observed
in 15 numbers of the 24 stocked, out of which 5 were unfertilized (improper
spermatophore attachment). After an incubation period of 25 - 32 days,
leading to hatching, seven lobsters bred again, of which 5 were fertilized and
2 were unfertilized. Post breeding, the females underwent a transition moult
resulting in reduced ovigerous seate and reduced windows. These animals
completed one more moult again, in a span of 150 days from the last
spawning, to enter into a second breeding cycle. A total of 20 animals
survived. 13 animals entered the breeding phase, 4 had unfertilized eggs. Of
these, 10 rematured again and bred.
90% of eyestalk ablated animals bred and spawned in a week's time
after ablation. Further growth progress and maturation in ablated ones was
slightly diminished. Five of the 20 numbers tried gave a second cycle in the
immediate moult itself. There was no delay and therefore continuous egg
production can be induced, compromising the growth. Fecundity and the
quality of eggs however, gets reduced.
53
3.3.3.1A T. orientalis
In 120 days of culture. females became active. Males were
comparatively smaller. Out of the 8 males (61 - 70 mm Cl), all males became
sexually mature while only 3 exhibited sexual activity Of the 16 females tried,
all females developed ovigerous setae beyond 66 - 70 mm CL. Only 6
developed, mated and bred. 5 gave fertilized eggs and 1, unfertilized. After an
incubation period of thirty-five days and a gap of five to ten days, rematuration
and spawning was observed in three lobsters, out of which one gave rise to
unfertilized eggs. Following hatching, these animals moulted into a prolonged
"intermoult" stage. Only ten females survived, completing a second moult in
which a second cycle of breeding was observed only in t3, after a span of
nearly 150 days. Of this two were fertilized and 1, unfertilized. However, the
males did not survive this entire period and new males had to be introduced.
3.3.4 Gonadosomatic Index
3.3.4A P. po/yphagus
3.3.4Ai Male
Average GSI values ranged from 0.48 to 0.77 in immature males of 41 - 55
mm Cl and from 0.84 to 1.61 in early maturing males of 46 - 60 mm CL. In
late maturing and mature males of 56 - 95 mm Cl, the average GSI values
ranged between 2.07 and 3.85. The highest GSI values were observed in
mature males of 66 - 80 mm CL. The average GSI values for different 5 mm
size (Cl) classes among immature, early maturing and late maturing/mature
males are graphically represented in Fig. 14 a. The GSI was seen to increase
with size among immature and early maturing males. In the late
54
maturing/mature group, the GSI increased from 2.07 in the 56 - 60 mm Cl
class to a peak of 3.85 in the 76 - 80 mm Cl class. Thereafter, it varied
between 3.2 and 3.4.
3.3.4Aii Female
Average GSI values ranged from 0.44 to 0.66 in immature females of 41 - 50
mm Cl and from 0.83 to 1.73 in early maturing females of 46 - 60 mm CL. In
late maturing and mature females of 56 - 100 mm Cl, the average GSI
values ranged between 2.97 and 7.73. The highest GSI values were observed
in mature females of 71 - 85 mm CL. In spent/recovery females of 75 - 100
mm Cl, the GSI fluctuated between 0.88 and 2.67. The average GSI values
for different 5 mm size (Cl) classes among immature, early maturing, late
maturing/mature and spent/recovery females are graphically represented in
Fig. 14 b. The GSI was seen to increase with size among immature and early
maturing females. In the late maturing/mature group, the GSI increased from
2.97 in the 56 - 60 mm Cl class and fluctuated between 7.00 and 7.73 in the
size range of 66 - 100 mm Cl. In the spent/recovery females, the GSI
remained at around 1.00 and showed a slight increase only in the highest size
class.
3.3.4B T. orientalis
3.3.4Bi Male
Average GSI values ranged from 0.45 to 0.7 in immature males of 41 - 55
mm Cl and from 1.09 to 1.76 in early maturing males of 46 - 60 mm CL. In
late maturing and mature males of 51 - 85 mm Cl, the average GSI values
55
ranged between 2.17 and 2.77. The highest GSI values were observed in
mature males of 66 - 70 mm CL. The average GSI values for different 5 mm
size (CL) classes among immature, early maturing and late maturing/mature
males are graphically represented in Fig. 15 a. The GSI was seen to increase
with size among immature and early maturing males. In the late
maturing/mature group, the GSI increased from 2.17 in the 51 - 55 mm CL
class to a peak of 2.77 in the 61 - 70 mm CL class. Thereafter, it decreased
slightly and then remained almost steady in animals above 71 mm CL.
3.3.4Bii Female
Average GSI values ranged from 0.6 to 0.88 in immature females of 51 - 65
mm CL and from 1.04 to 2.68 in early maturing females of 56 - 70 mm CL In
late maturing and mature females of 61 - 90 mm CL, the average GSI values
ranged between 4.16 and 4.9. The highest GSI values were observed in
mature females of 85 - 90 mm CL. In spent/recovery females of 75 - 100 mm
CL, the GSI fluctuated between 0.96 and 1.67. The average GSI values for
different 5 mm size (CL) classes among immature, early maturing, late
maturing/mature and spent/recovery females are graphically represented in
Fig. 15 b. The GSI was seen to increase with size among immature and early
maturing males. In the late maturing/mature group, the GSI increased from
4.16 in the 61 - 65 mm CL class and thereafter, did not show much variation
until the spent stage is reached, in the size range of 66 - 100 mm CL. In the
spent/recovery females. the GSI remained close to 1.00 and showed a slight
increase only in the highest size class.
3.3.5 Size at maturity
3.3.5A P. po/yphagus
3.3.5Ai Males
(a) Penile process
56
The male gonopore is visible in juveniles as small as 25 mm CL, but
only in the form of a tiny inconspicuous spot on the coxa of the fifth pair of
pereiopods, ventrally. As the animal grows, the gonopore develops into a
penile process with a hairy tip. The formation of the penile process is first
noticed in male lobsters of 36 - 40 mm CL. The smallest size at which a
penile process was observed was 36.6 mm. Development of the penile
process, is however, slow. About 28% of the animals in the size range of 51 -
55 mm CL, 53% of the animals in the size range of 56 - 60 mm CL and 100%
of the animals above 62 mm CL have well developed penile processes (Fig.
16 a).
Development of the penile process in males held in captivity was quite
similar to the progress seen in the wild. 50% of the males in the size range of
56 - 60 mm CL and 84% of the males in the size range of 61 - 65 mm CL
had well developed penile processes (Fig. 16 b).
(b) Maturing/mature testes
Males in the size range of 36 - 40 mm CL had immature testes. Signs
of gonadal development were observed in some males in the size range of 41
- 45 mm CL In males of 51 - 55 mm CL, the gonads are structurally
completely developed though the vas deferens remains thin without any
swollen ends. 53% of the males in the size range of 56 - 60 mm CL had
57
structurally complete and mature gonads with thickened vas deferens, swollen
at the distal end (Fig. 16 a). At this stage, histological sections revealed the
onset of spermatophore formation. 98% of the males in the size range of 61 -
65 mm CL were functionally mature.
(c) Relationship between carapace length and somatic lengths as
indices of sexual maturity
(i) Carapace length (CL) - Maximum width of carapace (MWC) : (Fig.
17 a)The lines of regression between CL and MWC (at the posterior end of
the carapace) for male lobster <50 mm CL and >50 mm CL did not show any
significant variation in slope or elevation.
(ii) Carapace length (Cl) - Ventral sternite length (VSl) : (Fig. 17 b)
The regression lines of VSL on CL in male P. po/yphagus before 50 mm CL
and after 50 mm CL did not show any marked difference in slope or elevation
(iii) Carapace length (Cl) - length of penile process (PPl) : (Fig. 17 c)
The regression lines of PPL on CL in juvenile and sub-adult/adult male P.
po/yphagus lie on two different elevations and the deflection from one line of
growth to the other lies at 50 mm CL This is the most important external
index of the onset of sexual maturity in the males as the development of the
penile process signifies the functional status of the male's capacity to
impregnate a female.
58
(iv) Carapace length (Cl) - leg lengths (III ll, IV II and V ll) : The
regression lines between CL and length of the third pair of pereiopods in male
P. po/yphagus of <50 mm CL and> 50 mm CL had different slopes and the
point of intersection was estimated to be 55.4 mm CL (Fig. 17 d). In the case
of the fourth (Fig. 17 e) and fifth (Fig. 17 f) pairs of pereiopods in male P.
po/yphagus, the regression lines differed significantly in their elevations,
indicating sharp deflections in growth patterns of the legs during the transition
from juvenile to sub-adult phase.
3.3.5Aii Females
(a) Ovigerous setae
Enlargement of the abdominal pleopods and segmentation of the
endopods begin in females of 46 - 50 rnm CL. More than 50% of the females
of 51 - 55 mm Cl have well developed pleopods. Development of ovigerous
setae begins at this size. The minimum size at which development of
ovigerous setae was noticed was 51.7 mm CL. About 50% of the females in
the CL range of 61 - 65 mm have fully developed ovigerous setae (Fig. 18 a).
In females held in captivity, however, the development of ovigerous setae
appears to begin in slightly higher size class, indicating higher somatic
growth. The size range in which 50% of the females had ovigerous setae was
66 -70 mm CL (Fig. 18 b)
(b) Maturing/mature ovary
Maturation of the ovary was studied in females collected from the
fishery. Females in the size range of 36 - 45 mm CL had immature ovaries.
59
Signs of ovarian development were observed in some females in the size
range of 46 - 50 mm CL. Ovarian development was evident in females of 51 -
55 mm CL, with the development of orangish colour of the ovary, visible
through the dorsal musculature. More than 50% of the females in the size
range of 66- 70 mm CL had ripe ovaries (Fig. 18 a).
(e) Egg brush
The development of the egg brush at the tips of the pereiopods
appears to coincide with the development of ovigerous setae and maturation
of the ovary. Egg brush formation was found in 7% of the sampled females in
the size range of 56 - 60 mm CL. 50% of the females in the size class of 66 -
70 mm CL and 98% of the females in the size class of 71 - 75 mm CL had
well developed egg brushes (Fig. 18 a). In captivity also 50% of the females in
the size range of 66 - 70 mm CL were found to have developed the egg brush
(Fig. 18 b).
(d) Formation of mating windows
Formation of mating windows, i.e. decalcification of the ventral sternal
plates at the base of the third, fourth and fifth pairs of pereiopods, begins in
females in the size range of 66 - 70 mm CL, after ovarian maturation. Almost
50% of the females of 71 - 75 mm CL have well developed pairs of windows
- two pairs each on the fifth and fourth pairs of pereiopods and one pair on
the third (Fig. 18 a). Decalcification begins on the lower most sternal plate,
i.e., at the base of the fifth pair of pereiopods. Window formation signifies that
the female is completely (physiologically and functionally) ready for mating. In
60
captivity also 50% of the females in the size range of 71 - 75 mm Cl were
found to have developed mating windows (Fig. 18 b).
(e) Occurrence of berried females
The minimum size class in which berried females were noticed in samples
from the fishery was 51 - 55 mm Cl and the smallest berried female recorded
measured 54.3 mm Cl and the largest measured 108 mm Cl. However, the
percentage frequency of berried females could not be used as an index to
estimate the size at first maturity as the percentage did not exceed 25% in
any size class from 51 - 55 mm to 106 - 110 mm CL There was a steady
increase in the percentage of berried females upto 81 - 85 mm CL, followed
by a decrease in the higher size classes and only 1 % of the sampled females
of 106 - 110 mm Cl were berried (Fig. 18 a). The peak occurrence of berried
females in the size range of 76 - 85 mm CL follows the completion of ovarian
maturation, development of ovigerous setae, window formation and egg brush
formation. The distribution of berried females thus serves to corroborate the
conclusions drawn from these indices. Occurrence of berried females was
higher in captivity, with more than 50% of the females in the size range of 71
- 80 mm Cl becoming ovigerous (Fig. 18 b)
(f) Relationship between carapace length, maximum width of
carapace, ventral sternite length and leg lengths as indices of sexual
maturity
(i) Carapace length (Cl) - Maximum width of carapace (MWC) : (Fig. 19
a) The lines of regression between Cl and MWC (at the posterior end of the
61
carapace) for female P. po/yphagus <50 mm CL and >50 mm CL differed in
their slopes and the intersection of the two lines was estimated to be at 45.7
mm CL, a size preceding the minimum size at which development of the ovary
was observed in some females.
(ii) Carapace length (Cl) - Ventral sternite length (VSl) : (Fig. 19 b)
The regression lines of VSL on CL in female P. po/yphagus had different
slopes and there was a clear difference in the relationship between the two
parameters before 50 mm CL and after 50 mm CL. The intersection of the two
lines was at 51.1 mm CL, signifying changes due to the animal's entry into
sexual maturity from 51 - 55 mm CL onwards.
(iii) Carapace length (Cl) - leg lengths (Ill ll, IV II and V ll) : The
regression lines between CL and different leg lengths showed variations in the
two size groups with the intersection points lying at 65.2 mm CL for the third
leg (Fig. 19 c), 45.7 mm CL for the fourth leg (Fig. 19 d) and 55.7 mm CL for
the fifth leg (Fig. 19 e). The fifth leg takes a different growth pattern just after
40 rnrn CL. The fourth leg is longer than the third initially but after 55 rnm CL,
the third leg overtakes the fourth. These legs playa role in copulation and
later, in grooming of the eggs during incubation, for which the legs should be
extended up to the brood chamber.
62
3.3.5Aiii Comparison between males and females
A comparison of regression lines of different somatic measurements
mentioned above, relative to CL in male and female P. polyphagus indicate
the following pOints of divergence in relation to sexual maturity -
(a) CL vs MWC : (Fig. 20 a) Initially, males have a higher ratio of MWC upon
CL, but beyond 65 mm CL, females exceed the males in this ratio.
(b) CL vs VSL : (Fig. 20 b) While females have a higher VSL to CL ratio
initially, the males exceed them beyond 50 mm CL, indicating the changes
required for the formation of mating windows. The ventral sternite in females
becomes broader and increase in length is suppressed.
(c) CL vs Leg lengths: While the third (Fig. 20 c) and the fifth (Fig. 20 e)
pairs of pereiopods are relatively longer in females in the juvenile phase, the
lengths take an upper deflection in males at about 45.1 mm CL and 44 mm
CL respectively. The fourth (Fig. 20 d) pair of pereiopods are almost similar in
length in both the sexes initially, but the length in males takes an upward
deflection at 36 mm CL These are important indicators of the onset of sexual
maturity in males as the pereiopods playa major role in the act of copulation
and impregnation.
From the results obtained, it is evident that while the size at first
physiological maturity is attained at 61 - 65 mm CL in male P. polyphagus
and at 66 - 70 mm CL in female p, polyphagus, the size at morphological
maturity is attained earlier, i.e, at 56 - 60 mm CL in males and at 61 - 65 mm
--.. ----~ -"'- __ \ !n;versity
3havilCi '" ." 63
CL in females. However, the size at functional m:tur~~ i~.~e females '~e s In
a little late, i.e., 71 - 75 mm CL, in tandem with formation of the mating
windows. From these inferences it can be concluded that the critical
maturation phase extends between 56 and 65 mm CL for males and between
66 and 75 mm CL for females. The size at onset of sexual maturity, judged
from the 25% success rate in development of different sexual characters
(Figs. 16 & 18), can be traced to 51 - 55 mm CL for males and 51 - 60 mm
CL for females.
3,3,58 T, orientalis
3,3.58i Males
(a) Maturing/mature testes
Males in the size range of 41 - 45 mm CL had immature testes. Signs
of gonadal development were observed in some males in the size range of 46
- 50 mm CL Almost 50% of the males in the size range of 51 - 55 mm CL
mature gonads (Fig. 21). At this stage, histological sections revealed the
onset of spermatophore formation. 97% of the males in the size range of 61
- 65 mm CL (and all males above 62 mm CL) had mature gonads and fully
developed accessory sexual traits and could be termed adults.
(b) Relationship between carapace length, maximum width of
carapace, ventral sternite length and leg lengths as indices of sexual
maturity
(i) Carapace length (CL) - Maximum width of carapace (MWC) : The
lines of regression between CL and MWC at the anterior end of the carapace
64
(AWC) for male lobster <50 mm CL and >50 mm CL differed in their slopes
and the intersection of the two lines was estimated to be at 52.1 mm CL (Fig.
22 a). The lines of regression between CL and MWC at the posterior end of
the carapace for male lobster <50 mm CL and >50 mm CL differed in their
slopes and the intersection of the two lines was estimated to be at 52.7 mm
CL (Fig. 22 b).
(ii) Carapace length (CL) - Ventral sternite length (VSl) : The
regression lines of VSL on CL in male T. orientalis before 50 mm CL and
after 50 mm CL had different slopes and the intersection point, i.e. the size at
which the growth of the VSL in relation to CL changes, was at 39.4 mm CL
(Fig. 22 c).
(iii) Carapace length (Cl) - leg lengths (III Wl, IV Wl and V Wl) :The
regression lines between CL and lengths of the third and fifth pairs of
pereiopods in male T. orienta/is differed significantly in their elevations,
indicating sharp deflections in growth patterns of the legs during the transition
from juvenile to sub-adult phase (Fig. 22 d & fl. In the case of the fourth pair
of pereiopods, the slopes were found to be different for the two size groups
and the point of intersection was estimated to be 42.4 mm CL (Fig. 22 e).
3.3.5Bii Females
(a) Ovigerous setae
Development of ovigerous setae on the abdominal pleopods begins at
46 - 50 mm CL in the wild. A small proportion (18%) of the females in the
65
size range of 51 - 55 mm CL had developed ovigerous setae. 50% of the
females in the CL range of 61 - 65 mm and all females above 71 - 75 mm CL
have well developed ovigerous setae (Fig. 23 a). The development of
ovigerous setae was quite similar in females held in captivity. The formation of
the setae begin at 46 - 50 mm CL, with about 15% of the females in 51 - 55
mm CL bearing ovigerous setae. (Fig. 23 b). 25% of the females of 55 - 56
mm CL and 50% of the females of 61 - 65 mm CL had ovigerous seate.
(b) Maturing/mature ovary
Among females sampled from the wild, ithe size range of 41 - 45 mm
CL had immature ovaries. Signs of ovarian development were observed in
some females in the size range of 46 - 50 mm CL. 50% of the females in the
size range of 61 - 65 mm CL had ripe ovaries (Fig. 23 a). All females above
76 - 80 mm CL were fully mature.
(c) Occurrence of berried females
Among the females sampled from the wild, the minimum size class in
which berried females were noticed was 61 - 65 mm CL. The smallest berried
female recorded measured 64.1 mm CL and the largest measured 100 mm
CL. However, as in the case of P. po/yphagus, the percentage frequency of
berried females could not be used as an index to estimate the size at first
maturity as the percentage did not exceed 26% in any size class from 61 - 65
mm to 93 - 100 mm CL (Fig. 23 a). The percentage of berried females
increased from 11 % in lobsters of 61 - 65 mm CL to 26% in lobsters of 81 -
85 mm CL, followed by a decrease in the higher size classes. The peak
66
occurrence of berried females in the size range of 71 - 85 mm CL follows the
completion of ovarian maturation and the development of ovigerous setae. As
seen in the case of P. polyphagus, the distribution of berried females thus
serves to corroborate the conclusions drawn from these indices.
Among females held in captivity, the occurrence of ovigerous condition
was first seen in animals of 61 - 65 mm CL. 36% of the females of 71 - 75
mm CL were ovigerous (Fig. 23 b). Maximum occurrence of ovigerious
females was observed in the size range of 71 - 85 mm CL.
(d) Relationship between carapace length, maximum width of
carapace, ventral sternite length and leg lengths as indices of sexual
maturity
(i) Carapace length (CL) - Maximum width of carapace (MWC) : The
lines of regression between CL and MWC at the anterior end of the carapace
(AWC) for female lobster <50 mm CL and >50 mm CL differed in their slopes
and the intersection of the two lines was estimated to be at 47.6 mm CL (Fig.
24 a). The lines of regression between CL and MWC at the posterior end of
the carapace for female lobster <50 mm CL and >50 mm CL differed in their
slopes and the intersection of the two lines was estimated to be at 43.9 mm
CL, a size preceding the minimum size at which development of the ovary
was observed in some females (Fig. 24 b).
(ii) Carapace length (Cl) - Ventral sternite length (VSl) : The
regression lines of VSL on CL in female T. orientalis had different elevations
67
and there was a clear difference in the relationship between the two
parameters before 50 mm CL and after 50 mm CL. In Fig 24 c, the area
between 46 mm and 55 mm CL marks the area of deflection from one line of
growth to the next, signifying changes due to the animal's entry into sexual
maturity.
(iii) Carapace length (CL) - Leg lengths (III WL, IV WL and V WL) : The
regression lines between CL and lengths of the III and IV pereiopods (Figs. 24
d & e) differed in their elevations in the two size groups. The deflection area
lay in the range of 49 - 53 mm CL. The intersection of the regression lines for
the fifth pereiopod was at 47.5 mm CL (Fig. 24 I).
3.3.5Biii Comparison between males and females
A comparison of regression lines of different somatic measurements
mentioned above, relative to CL in male and female T. orienta/is indicate the
following pOints of divergence in relation to sexual maturity -
(a) CL vs AWC : Initially, females have a higher ratio of AWC upon CL,
but beyond 55 mm CL, the males exceed the females in this ratio (Fig. 25 a).
(b) CL vs MWC : Females have a higher ratio of MWC upon CL and the
point of convergence is approached only beyond 90 mm CL (Fig. 25 b). This
indicates the adaptation of the female, even before the onset of sexual
maturity, to accommodate the changes involved with ovarian development.
68
(e) CL vs VSL : While males have a higher VSL to CL ratio initially, the
females exceed them beyond 48 mm CL (Fig. 25 c)
(d) CL vs Leg Lengths: The third and fourth pereiopods remains longer
in females. (Fig. 25 d & e) While the fifth pair of pereiopods is relatively
longer in females in the juvenile phase, the length takes an upper deflection in
males at about 47 mm CL and thereafter, the ratio is higher in males (Fig. 25
f). This is an important indicator of the onset of sexual maturity in males as the
fifth pair of pereiopods (at the base of which is situated the male gonopore)
plays a major role in the act of copulation and impregnation. Although the
relationships between the third and fourth pairs of pereiopods do not show
any significant variation with CL between sexes, it is significant to note the
dominance of these legs in females, since these pereiopods, particularly the
third (which holds the female gonopore), play an important role in holding
onto the male at the time of copulation and in directing the eggs into the brood
chamber at the time of oviposition. Following copulation and OViposition, the
pereiopods remain actively engaged in grooming the eggs during the
incubation period.
From the results obtained, it is evident that while there is not much time
frame between the attainment of morphological, physiological and functional
maturity in T orienta/is. The size at first maturity is attained at 51 - 55 mm CL
in male T orienta/is and at 61 - 65 mm CL in female T orienta/is. It can be
concluded that the critical maturation phase in T orienta/is is not as extended
to several size groups as in P. po/yphagus. The size at onset of sexual
69
maturity, judged from the 25% success rate in development of different sexual
characters (Figs. 21 & 23), can be traced to 46 - 50 mm Cl for males and 51
- 55 mm Cl for females.
3.3.6 Fecundity
3.3.6A P. po/yphagus
The fecundity of P. po/yphagus ranged from 158000 eggs (64.5 mm
Cl) to 931000 eggs (118.4 mm el), with an average fecundity of 455000
eggs for reproductively active females in the size range of 64 - 119 mm CL.
The relationship between fecundity and carapace length (Fig.26 a) was
derived as -
Fecundity ('000) = 12.531 Cl - 636.73 (r2 = 0.9685)
3.3.68 T. orientalis
The fecundity of T orienta/is ranged from 19600 eggs (60 mm Cl) to
59500 eggs (102 mm Cl), with an average fecundity of 39300 eggs for
reproductively active females in the size range of 60 - 102 mm Cl. The
relationship between fecundity and carapace length (Fig. 26 b) was derived as
Fecundity ('000) = 0.7285 CL -19.153 (r2 = 0.9424)
70
3.4 DISCUSSION
3.4.1 Sexual Dimorphism and Secondary Sexual Characters
Lobsters are bisexual animals exhibiting sexual dimorphism, and
conform to the general decapod crustacean reproductive pattern which has
been extensively studied and described (Rahman, 1967; Ryan, 1967;
Haefner, 1976 and Zuckner, 1978). Maturation is a process involving
several physical and physiological changes during the life of an animal,
enabling it to reach a state when it can become biologically productive
and effect propagation of its kind. The process of maturation begins
when the animal reaches a certain optimum size and is exposed to
favourable environments. During the juvenile phases of its life history,
the process of visible growth dominates as the vital physiological
activity of the animal. However, as the animal ages, the growth
processes slow down and there is a diversion of energy for the
development of sexual characteristics, both primary and secondary. The
animal is now in a state of maturation. The end result of maturation is
the formation of an adult completely capable of mating and producing
offspring. The prime aim of maturation is the structural and functional
development of the reproductive organs which are responsible for
production of male and female gametes that can give rise to an
embryo upon fusing. The maturation process is often manifested through
changes in certain externally visible structures, which indicate the internal
changes that occur simultaneously or will occur in close succession.
These structures are referred to as secondary sexual characters.
These traits serve the purpose of indicating the maturity state of the
71
animal and its sex. Many such traits also serve different purposes
leading to mating and brooding.
Sexual dimorphism and the secondary sexual characters identified for
the two species in the present study, and their usefulness as indices of sexual
maturity conform to earlier findings in other lobster species (Berry, 1970;
George and Morgan, 1979; Lipcius ef a/., 1983; Bertelsen and Horn, 2000;
Chubb, 2000; DeMartini et a/. , 2005). George (2005) observed the interesting
trend from simple to complex mating structures in both males and females,
reflecting patterns of speciation in the spiny lobster genus Panu/irus. Unlike
the simple gonopore seen in the primitive species, P. cygnus, the structure of
the male gonopore in P. po/yphagus is similar to the complex gonopore
described for the recently evolved species, P. homarus (MacDiarmid and
Sainte-Marie, 2006), indicating the evolutionary status of this species.
Hossain (1978) discussed sexual dimorphism in T. orienta/is based on the
telson , which, in sexually mature females, bore elongated plumose setae at
the end, presumably to protect the berried eggs and also to enable water
circulation among the berried eggs.
3.4.2 Reproductive System - Structure and Development
Lobsters conform to the generalized decapod reproductive pattern
(MacDiarmid and Sainte-Marie, 2006) with paired ovaries or testes lying
dorsally in the body cavity leading via paired oviducts in females or vasa
deferentia in males, to reproductive apertures or gonopores on the coxa of the
third pair of pereiopods in females and the fifth pair in males (Meglitsch,
72
1967). The reproductive anatomies of P po/yphagus and T. orientalis, as
observed in the present study, follow this general pattern. The maturation
process and developmental changes in the gonads observed in the present
study also conform to the general pattern described for other lobsters and
crustaceans (Fielder, 1964; Yano, 1988; Nakamura, 1990; Minagawa and
Sano, 1997).
Observations in the present study on histological changes in the
gonads during the maturation cycle conform to descriptions given for other
crustaceans and lobsters ((Fielder, 1964; Yano, 1988; Nakamura, 1990;
Demestre and Fortuno, 1992; Minagawa and Sano, 1997; Balasubramanian
and Suseelan. 2000). The production of spermatocytes inside seminiferous
lobules or acini. and oogenesis through different stages of vitellogenesis
observed in the two species are similar to the observation made on other
crustacean and lobster species.
A clear difference between P. po/yphagus and T. orienta/is is seen in
the histological development of the male gonads. While the villiform typhlosole
in P. po/yphagus conforms to the descriptions given for other palinurid
lobsters (Berry and Heydorn, 1970). the typhlosole in T. orienta/is is not
villiform and is more ovoid in shape. The typhlosole in T. oriental is was found
to lack a glandular epithelium, and was instead found to be with connective
tissue. The structure and nature of the typhlosole may be directly related to
the nature of the spermatophore. The spermatophore in T. orienta/is is not like
the complex one seen in P. po/yphagus and there is only a singe type of
73
gelatinous fibrillar matrix (which remain mucoid even after impregnation) in
which the spermatophore masses are embedded.
The structure of the oviduct too is different in the two species. The
oviduct is seen to be more flattened in T orienta/is and the lumen appears to
be pushed to the lateral peripheral sides by a mass of connective tissue which
is placed centrally. This structure completely differs from the oviduct in P.
po/yphagus, which has a large central lumen, with villi and a lining of high
columnar epithelial cells.
3.4.3 Mating and Spawning
Mate selection, courting and copulation in a lobster species are
intricately related to the distinctive morphology of the sexes. Olfactory, visual,
auditory and tactile stimuli have been known to playa role in the attraction,
recognition and choice of mates in different lobster species (MacDiarmid and
Sainte-Marie, 2006). The visual sense in spiny lobsters is well developed
especially in tropical lobsters of the genus Panulirus (Meyer-Rochow, 1975,
1988). MacDiarmid and Sainte-Marie (2006) stressed that while olfaction
plays the critical role in determining mate attraction, recognition and choice in
clawed lobsters, vision is likely to play an important role in spiny lobsters,
increasing from least critical in Jasus to most critical in the recently evolved
species such as P. ornatus. Spiny lobsters of the Stridentes group also
possess a stridulating organ (Patek, 2001). MacDiarmid and Sainte-Marie
(2006) in a review of lobster reproduction mention that in Pa/inurus e/ephas,
stridulation by a reproductive female attracts mature males from a radius of at
74
least 15 m, and in the laboratory, males were found to move towards an
underwater speaker broadcasting female stridulation. Berry, 1970 reported
similar stridulation and male reaction in P. homarus. In the present study
mature females of P. po/yphagus were also found to use the stridulating organ
to attract males.
Atema and Voigt (1995) and MacDiarmid and Kittaka (2000) have
reviewed courting and cohabitation in spiny and clawed lobsters. The courting
frontal approach in spiny lobsters has been reported to continue from several
minutes to 11 days prior to copulation (Lipcius and Herrnkind, 1985;
MacDiarmid, 1989b). Copulation in lobsters is usually very brief, typically
lasting less than a minute in nephropid (Framer, 1974; Talbot and Helluy,
1995) and in palinurid lobsters (MacDiarmid and Kittaka, 2000). In the present
study, copulation was found to last for about two to three minutes In P.
po/yphagus. There is not much information on the mating behaviour of
scyllarid lobsters in captivity. In the present study, copulation in T. orienta/is
was found to be slightly prolonged, lasting for five minutes. Interestingly, the
courting approach is also different in this species, with the male crawling on
top of the female and overturning it. Copulation takes place with the animals
in reverse positions and they swim away in opposite directions after the
process.
Sperm transfer from male to female during mating in crustaceans
is effected by means of a spermatophore, which is a specialized sperm
75
packet serving as a vehicle for sperm transport. The spermatophore
essentially contains the sperms surrounded by protective layers of
cellular secretions produced in the vas deferens (Aiken and Waddy,
1980, Kooda-Cisco and Talbot, 1982) Berry and Heydorn (1970)
described the spermatophoric mass in macrurans as being generally
composed of three components - a sperrnatophoric tube, a basal
adhesive matrix and a protective gelatinous matrix. The nature of the
sperrnatophoric masses in P. po/yphagus and T. orienta/is are also seen to be
completely different. The matrix of the spermatophoric mass in P. po/yphagus
changes from its gelatinous form to a hardened stiff form when exposed to
seawater, which is similar to the description given for the spermatophoric
mass of Pa/inurus gi/christi (Berry and Heydorn, 1970). In species exhibiting
external fertilization, the soft mucoid spermatophore extruded and fixed
onto the female thelycum usually hardens, following chemical changes
induced by exposure to seawater. (Radha and Subramoniam, 1985). In
most decapod groups, this hardening of the spermatophore has been
shown to be due to chitin (Spalding, 1942, King, 1948, Uma and
Subramoniam, 1979) and phenolic tanning (Malek and Bawab, 1974,
Subramoniam, 1984). However, this is not found to be the case in T.
orientalis. The spermatophoric mass of T. orientalis lacks an external
gelatinous matrix. The spermatophores remain embedded in a fibrillar mucoid
matrix, which does not harden on exposure to sea water. It breaks open in a
few hours after exposure to seawater. Berry and Heydorn (1970) have given a
similar description for the nature of the spermatophoric mass and its matrix in
J. lalandii.
76
3.3.3.1 Breeding in captivity
Maturation and breeding in captivity remain to be major
challenges in the evolution of husbandry packages for lobsters. The
establishment of culture conditions in which reproduction can be controlled to
produce larvae all year round is one of the requirements for successful larval
rearing of spiny lobsters (Vijayakumaran et al., 2005). Captive breeding,
mating behaviour, mate selection, pre-mating courtship and copulation have
been well studied in the American lobster H. american us (eg. Atema and
Voigt, 1990; Waddy et ai, 1995). Over the last 20 years, there have been an
increasing number of in situ experimental studies that have expanded our
understanding of the complexities of lobster reproduction (MacDiarmid and
Sainte-Marie, 2006) Laboratory experiments have determined that long days
enhance female gonadal development and spawning frequencies in
Panulirus argus and P. japonicus, while warmer temperatures significantly
accelerate these processes in these species (Lipcius and Herrnkind, 1987;
Matsuda et al., 2002) as well as in P. cygnus (Chittleborough, 1976). In
captive breeding experiments in P. homarus, Vijayakumaran et al. (2005),
reported production of four broods in a year by a single female. The number
of spawnings by individual lobsters also varied from one to seven within the
same year. Senthilmurugan et al. (2005) reported repetitive breeding of P.
ornatus. As in the observations made on P. polyphagus in the present study,
there was a considerable time gap (25 to 63 days) between spawning and the
pre-mating moult in female P. ornatus. The growth rate of male P. ornatus
was higher than that of females, as seen in the case of P. polyphagus. Three
77
spawnings in six months just after attaining sexual maturity were reported in
P. ornatus. These observations and the observations made in the present
study in P. polyphagus reiterate the fact that spiny lobsters are amenable to
captive breeding, given the right environmental cues, as suggested by
sachlikidis et al., (2005). Under highly favourable conditions, adult females
are capable of spawning more than once within the same breeding
cycle, thereby exhibiting higher total fecundity. Ino (1950) suggested
that a considerable number of female P. japonicus spawn twice in a
season. Sutcliffe (1953), Williams (1965) and Buesa (1969) recorded
two spawnings in some female P. argus in a single season, without a
moult between two breeding cycles. Berry (1971) observed upto four
repetitive breeding cycles in P. homarus In a year. Chittleborough (1976)
observed two spawnings in a season In about 10.5% of the female
population of P. longipes cygnus George in the wild while about 66.7%
of the females stocked in an aquaria at lower ambient temperature but
with an abundance of food bred twice in a season.
Compared to spiny lobsters, captive breeding of scyllarid lobsters is an
area less explored. The observations made in the present study point to the
fact that T orientalis has a faster growing regime and can be easily
maintained in captivity. However, the breeding responses were not as high as
seen in the case of P. polyphagus, suggesting the need for identifying the
critical environmental cue that may trigger the right physiological response for
captive breeding. Kizhakudan et al. (2004) in further experiments on captive
rearing of scylla rids reported high incidence of maturation and breeding in
78
captivity. Water quality and photoperiod were found to playa major role and
the animals were reared in larger tanks with increased water depth. A major
change from the experiments carried out in the present study was the use of
clam meat as brood stock diet. In the present study, due to limitations in the
natural availability of clams and the abundance of the gastropod Turbo sp.,
the latter was chosen as the standard diet for all experimental purposes.
3.4.4 Gonadosomatic Index
Gonadosomatic Index (GSI) has been used to examine ovarian
development and to obtain information on the spawning season and
reproductive cycle in various crustaceans (Aiken and Wady, 1980; Minagawa,
1997). Although GSI by itself does not provide credible information on ovarian
development, it provides useful information on ovarian cycles which can
supplement detailed information obtained from morphological, anatomical
and histological studies. Studying the reproductive cycle in P. japonicus,
Minagawa (1997) found that ovarian development, particularly, in smaller size
classes, corresponds well with the changes in GSI. This was found to be true
in the present study also. In size classes between 46 and 60 mm CL, in
maturing individuals, the GSI was found to increase. Maximum GSI values
correspond with dominance of mature individuals. Thereafter, in sizes above
70 mm CL, the GSI was found to fluctuate, probably due to the influence of
repetitive breeding cycles and to intermittent growth phases (in female P.
po/yphagus) before the next phase of breeding.
79
3.4.5 Size at Maturity
The size at first maturity is an important indicator of the reproductive
capacity of populations, and thus is an important tool in stock assessment as
alterations in the size at maturity over space and time may be indicative of the
effects of environmental and fishing impacts on the stock. The size at first
maturity is defined as the minimum size at which 50% of the
population has entered into a state of advanced maturation and is
usually estimated by plotting the percentage of mature animals in different
body size classes in a sampled population against size, and directly reading
the size at which 50% are mature. In decapods, the size at first maturity
is usually studied with reference to physiological maturation (the size at
which the gonads attain maturity) and physical maturation (the size at
which the animal is capable of mating and spawning). There is often a
gap in time between the occurrence of physiological and physical
maturity and hence the two phenomenon may not occur at the same
size (Jones, 1988), and both must be known to determine the size at
true sexual maturity (Stewart et aI., 1997). Mac Diarmid and Sainte-Marie
(2006) define three basic indicators of maturity that can each be assessed by
one or more criteria:
• Morphological maturity, detected by development of external body
parts representing secondary sexual characters
• Physiological maturity, reflected in the development of gonads and
accessory glands
80
• Functional maturity, revealed by internal or external features of
behaviour indicating past or current breeding activity
Jones (1988) observed that physiological and physical (or functional) maturity
in scyllarid lobsters may not occur at the same size, and both must be known
to determine the size at true sexual maturity.
Estmates of size at first maturity in lobsters are often limited by several
factors. The probability of the sampled population representing only a small
section of the size groups, or variability in the catchability of mature and
immature lobsters (particularly if the lobsters tend to change habitats with the
onset of maturation) are likely to make the estimates vulnerable to bias
(Farmer, 1974; Tully et al., 2001). The size at first maturity in female lobsters
is usually estimated using functional criteria of egg-bearing (Kensler, 1967;
Aiken and Waddy, 1980), the presence of fresh or spent spermatophores and
resorbing ova, physiological criteria of ovary colour and size, oocyte size and
development of cement glands on the pleopods and morphological criteria of
abdomen and pleopod development (Mac Diarmid and Sainte-Marie, 2006).
Staging based on histological examination of gonads provides more detailed
information than any other indicator (West, 1990). The percentage of
ovigerous (berried) females in the sampled population has been described to
give a reliable estimate of the size at maturity in the spiny lobster J lalandii
(Heydorn, 1969) since he found that after a certain size there was sharp
increase in the percentage of ovigerous condition and the same continued in
higher lengths. However, Berry (1971) found that in P. homarus, the
percentage of ovigerous females showed no marked increase at any
81
particular size and the larger size classes did not show a very high incidence
of ovigerous condition. He attributed this to repetitive breeding in this species.
Kagwade (1988) reported that the percentage frequency of ovigerous P.
po/yphagus in Bombay waters was erratic at various class intervals and at no
length the frequency reached beyond 20.7%. She too attributed this to
repetitive breeding. Observations made in the present study on the
distribution of berried (ovigerous) females in the trawl landings of P.
po/yphagus at Veraval and Mangrol trawl landing centres, indicate a similar
trend. The maximum occurrence (25%) of ovigerous females was observed in
the size range of 81 - 85 mm CL. However, while Kagwade (1988) has
advocated direct observation of the maturity stage of ovaries as a more
reliable method for identifying sexually mature female P. po/yphagus,
decreasing catches and high demand for this commodity has greatly restricted
the availability of sufficient specimens for analysis in the present study
One of the most important external indicators of sexual maturity in
females is the presence of fully developed ovigerous setae on the abdominal
pleopods, to which spawned fertilized eggs remain attached till the larvae are
hatched. Fielder (1964) and Pollock (1982) have recognized the identification
of mature females through the presence of these setae. Paterson (1969)
reported that in some species like J. /a/andii there is a regular cycle of
appearance and disappearance of these setae. Kagwade and Kabli (1996) did
not find any significant relationship between ovigerous setae and maturity in
female T. orienta/is. In the present study it was observed that the appearance
and development of the ovigerous setae for the first time coincides with the
82
onset of sexual maturity in both, P polyphagus and T. orientalis. The number
and size of the setae reach a maximum at the time of egg bearing. After the
first batch of eggs are completely hatched/removed from the pleopods, there
is a reduction in the density of the ovigerous setae, which later increases
during the successive breeding cycle.
George (2005) mentions the role of decalcified windows on the female
sternum in the spiny lobster genus Panulirus, which can be used to determine
maturity (e.g. Lindberg, 1955; Velazquez, 2003). However, while George
(2005) has described the presence of three pairs of mating windows in female
p, polyphagus, the present study clearly shows the presence of four pairs of
mating windows in this species - one pair each at the base of the third and
fourth pairs of pereiopods and two pairs at the base of the fifth pair of
pereiopods. The process of decalcification, beginning from the fifth pair of
pereiopods and progressing up to the third, is found to be a good indicator of
the functional maturity of the female, indicating that it is ready for
impregnation.
In animals with highly complicated and specialized reproductive
development and behaviour, it would always be advantageous to assess the
sexual maturity on the basis of more than two external or internal indicators of
maturity. The size at which physical maturity occurs in lobsters has been
identified by examining discontinuities (changes in slope) in the linear
relationships between body size and certain externally visible features.
Female maturity has been associated with allometric changes in the length of
83
pleopods, the length of the pleopodal setae, telson length or the width of the
abdomen relative to carapace length, which all change in relation to
preparation for first spawning (Street, 1969: Hossain, 1978b: Aiken and
Waddy, 1980: Pollock and Augustyn, 1982: Jones, 1988: Stewart et al., 1997;
Lizarraga-Cubedo et aI., 2003; Kulmiye, 2004; DeMartini et ai, 2005).
MacDiarmid and Sainte-Marie (2006) recommend that easily measured
appendage length to body size relations should be routinely applied to provide
estimates of female SOM (Size at Onset of Maturity) in lobsters, but only after
this approach has been validated by undertaking histological studies of
gonadal maturation. In the present study, the size at maturity in females and
males of P polyphagus and T. orientalis was estimated from different indices
of maturity and corroborated by histological observations on the progress of
gonadal development.
Assessment of size at maturity in males is much more difficult than in
females. Male physiological maturity has been determined by the presence of
mature spermatozoa in vasa deferentia of several spiny lobsters (Heydorn,
1969; Berry, 1970; MacDiarmid, 1989; Turner et ai, 2002) and in the clawed
lobsters H. american us and Nephrops norvegicus (Farmer, 1974). However,
physiological maturity need not necessarily indicate functional maturity. Male
functional maturity has often been associated with a change in the dimensions
of the first cheliped in clawed lobsters or of the second or third pereiopods in
spiny lobsters, relative to CL (MacDiarmid and Sainte-Marie, 2007). Berry
(1970), Lipcius et al., 1983, Bertelsen and Horn (2002) have associated the
extreme development of the second and third pereiopods of some male spiny
84
lobsters with their ability to extract females from their dens. The change in the
size of the pereiopods normally occurs after physiological maturity has been
attained. George and Morgan (1979) described a method of determining this
by plotting the leg size against the CL, for immature and mature lobsters. The
size at maturity is then indicated by the point of upward deflection or the point
of intersection of the regression lines of immature and mature lobsters. In the
present study comparative analyses were done from regression lines of
different somatic length against the carapace length in two size groups within
each sex of either species and from regression lines generated for males and
females without size differentiation. From the inferences drawn on size at
maturity for the two species, it is evident that in both species, the males
mature earlier than the females. While smaller males mate with larger
females, possibly of the same clutch, in T. orientalis, larger males mate with
smaller females, possibly of the same clutch, in P. polyphagus. This is due to
the differential growth exhibited by the sexes. Between the two species, T.
orienta/is exhibits more potential for faster maturation and completion of
breeding cycles. The larval phase is much shorter and larval rearing is also
relatively more feasible in T. orienta/is (Kizhakudan et ai, 2004). These
observations suggest the candidature of T. orientalis for aquaculture while the
development of husbandry practices for P po/yphagus will depend on
improved captive breeding and larval rearing to settlement.
3.4.6 Fecundity
Fecundity is a measure of fertility of an animal. It is usually
expressed in terms of the number of eggs capable of being produced
85
by an individual during a breeding cycle. Fecundity in lobsters is greatly
influenced by external factors like water temperature, pH and nutritional
factors. The number of eggs produced is also directly related to the
size of the lobster. In semi-enclosed areas and indoor experiments,
density and competition for food is also an important factor determining
the reproductive status and fecundity of lobsters. The total number of
eggs produced by an animal during its life time is the net result of the
interplay between two variable factors - the breeding frequency and the
number of eggs produced in each breeding cycle. Since both these
factors are independently subject to alterations in the environment, a
measure of the total observed fecundity deviates greatly from the actual
fecundity capacity of the animal. A better picture of the animal's
fecundity can be obtained by taking into account the fecundity per
breeding cycle. However, such observations require data collected over a few
years, from a large number of animals, which is beyond the scope of the
present study since lobsters are a high-demand, high-value commodity facing
the crisis of dwindling catches.
Fig.4a
p .... ~.'- .... :c, _~ .. _' _f
V
<1.
b.
Walking legs of P. polyphagus a. female (i) III WL (ii) IV WL (iii) V WL
(iv) propodus and dactylus of V WL in adult female forming a claw like structure
b. male (i) III WL (ii) IV WL (iii) V WL
Fig.4b Abdominal pi eo pods of adult female P. polyphagus showing exopods (ex ), endopods (en) and ovigerous setae (as) (i) I (ii) 1\ (iii) 1\1 (iv) IV
Fig.4c Development of penile process in male P. po/yphagus a. immature b. early maturing c. maturing d. developed e. active & ripe s. setae p. pigmentation m. membranous cuticle
cl. b.
c.
e· r.
Fig. 5 Formation of decalcified mating windows in female P. po/yphagus
a. clear ridges; no decalcification b. decalcification begins from posterior tip of sternum c. one pair of windows (w ) on V thoracic sternite d & e. 3 windows (2 on V and 1 on IV) f. 4 windows (2 on V, 1 on IV, 1 very small on III)
Fig. Sa
~.-:-.~ I
Iv
Walking legs and gonopore (g) of T. orientalis a. female (i) I WL (ii) II WL (iii) III WL (iv) IV WL (v) V WL (vi) coxa of III WL with gonopore
b. male (iv) IV WL
(i) I WL (v) V WL
(ii) II WL (iii) III WL (vi) coxa of V WL with gonopore
Fig.6b Abdominal pleopods of adult female T. orientalis showing exopods (ex), en do pods (en) and ovigerous setae (as) (i) I (ii) II (iii) III (iv) IV
Fig. 7
c.
Development of male reproductive system in P. polyphagus a. early maturing b. mature c. active adult t - testis, at - anterior testis, mt - middle testis, pt -posterior testis, p - proximal vas deferens, d - distal vas deferens, pp - penile process, ej - ejaculatory duct, tb -transverse bridge
Fig. 8
o
a·
c.
Development of female reproductive system in P. polyphagus a. immature b. maturing c. mature d. ripe o - ovary, ao - anterior ovary, mo - middle ovary, po _ posterior ovary, ov - oViduct, tb - transverse bridge
Fig. 9
~.
d..
e·
Developmental stages of oocytes in P. polyphagus, as observed under a Light Microscope (scale: 125 11m) a. immature non-vitellogenic stage b. stage 1 of primary vitellogenesis c. stage 2 of primary vitellogenesis d. stage 3 of primary vitellogenesis e. stage 1 of secondary vitellogenesis f. stage 2 of secondary vitellogenesis em - egg membrane, vo - vacuole, yg - yolk granule
Fig. 10
t
ct.
Development of male reproductive system in T. orientalis a. immature b. mature c. active adult t - testis, at - anterior testis, mt - middle testis, pt -posterior testis, p - proximal vas deferens, d - distal vas deferens, g - gonopore, ej - ejaculatory duct
Fig. 11
:1:.
Co.)
Gi--r:rl-~ SF~~
''-J---f--~'n=<8 ~
Schematic illustration of the developmental stages of male spermatophore in P. polyphagus and T. orientalis a. testis (te) with proximal and distal vas deferens (p &d), b. c.s. of anterior testis showing spermatocytes packed in acini (a), c. c.s. of proximal vas deferens showing spermatophore and gelatinous matrix, d. C.s. of distal vas deferens showing typhlosole (t ) and spermatophores (s ), e. c.s. of distal ejaculatory duct, f. loop-like convoluted arrangement of spermatophore tubules (sf) in distal vas deferens, g. c.s. of distal vas deferens in T. orientalis showing typhlosole (t ) and spermatophores (s ) embedded in gelatinous matrix, h. loop-like convoluted arrangement of spermatophore tubules (sf) in distal vas deferens in T. orientalis
Fig. 12
-, o o
c.
e.
Development of ovary in female T. orientalis
o o
t.
a. immature b.& c. early maturing d. late maturing f. ripe g. spent recovery
.. ; . • • • ~ . •
o - ovary, ao - anterior ovary, mo - middle ovary, po _ posterior ovary, ov - oviduct, tb - transverse bridge
Fig. 13
4..
b.
Diagrammatic representation of courting and mating behaviour a. P. polyphagus b. T. orientalis
iii Cl
iii Cl
4.5
4
3.5
3
2.5
2
1.5
1
0.5
0 II) ...
Fig. 14 a
10
9
8
7
6
5
4
3
2
1 ... 0
'" ... ~ ...
Fig. 14 b
• 1m
.... -- • Ern
• Lm/M
o II)
CD ... II) II)
o CD
CD II)
'" CD o .... CD CD
CL (mm)
'" .... o co
CD .... '" co
o
'" CD co
Gonadosomatic Index in male P. po/yphagus
1m
.. --- -Em
• Lm/M
)( Sp
.!! . -I •
Jf.
0 '" 0 II) 0 II) 0 '" 0 '" '" '" CD CD .... .... co co '" '" CD ~ CD ~ CD ~ CD ~ CD ~ ... '" II) CD CD .... .... co co '"
CL (mm)
Gonadosomatic Index in female P. po/yphagus
II)
'"
0 0 ~
CD
'"
4
• 1m 3.5 - -- ·Em
3 • LmlM r
r 2.5 ~~ T
en 2 1
CJ ·r 1.5 ,
• I . - ~.
1
0.5 ~ 0
I() 0 I() 0 I() 0 I() 0 I() .... I() I() '" '" .... .... "" "" , , , , , , , , , ~ '" ~ '" ~ '" ~ '" ~ .... .... I() I() '" '" .... .... "" CL (mm)
Fig. 15 a Gonadosomatic Index in male T. orientalis
7 1m
6 - .-- -Em
• LmlM I 5
~ I .. I )( Sp
4 en CJ
3
. ' I· -• of 2
, • -'" 1 ! ~ ""
• 0
I() 0 I() 0 I() 0 I() 0 I() '" '" .... .... ex> ex> Ol
~ '" ~ '" ~ '" ~ '" I() lD to to .... .... en IX)
CL (mm)
Fig. 15 b Gonadosomatic Index in female T. orientalis
100
90
Ii: 80 ::J 70 >-..: ::;; 60 >-...J 50 ...J ..:
40 ::J >< w 30 '" ~ • 20
10
0 0 ~
'" M
Fig. 16 a
100
90
Ii: 80 ::J
70 >-..: ::;; 60 >-...J 50 ...J ..: ::J 40 x w
30 '" ;;'1 20
10
0 0 ~
'" M
Fig. 16 b
-.- penile process
-o.-mature testes
n =261
'" 0 '" 0 '" 0 '" 0 '" 0 '" ~ '" '" '" '" .... .... co co (7) (7) , :;;: '" ~ '" ~ '" ;:: '" 0; '" ~
~ '" '" '" '" .... co (7)
CL (mm)
Size at sexual maturity in male P. po/yphagus (wild) derived from physiological and functional maturity indices
----.- penile process
n =38
'" 0 '" 0 '" 0 '" 0 '" 0 ~ '" '" '" '" .... .... co co (7) , , , , , , :;;: '" ~ "' U; "' ~ "' 0; "' ~ '" '" "' .... .... co
CL(mm)
Size at sexual maturity in male P. po/yphagus (captive) derived from functional maturity index
'" (7) , ~ (7)
" R' = 0.9893
" a<50mmCL
• ::0&0111111 Cl
" '55 g u ~" "
35
~. ,.
,. 35 " " " " " ~ ~ '" el!mm)
a. CL- MWC
" R'.O."" 20
.<60mmCL
o::o60mmCL
-" E g ~ • • 10
.~--~--~----~--~--~--~ •
"" 200
E 150 g ~ ~
> 100
.. •
20 .. .. ellmm)
c. CL - PPL
,,<50mlll CL
·>50mmCL
20 60
CLlmm)
.. 10 •
R" -0.9923
80 100
e. CL-IV LL
120
120
"
" .<60mmCL R2"O.ni
• >60mmCL
" • ~46 ~
~
>
" 26 /..~. " 26 " .. .. " " .. .. 10 • 11.
ellmm)
b. CL - VSL
'80
.<50mmCL R''' 0.9921
'" o>50mmCL
180
,,,
80
"~~--~~--~--r--r--~~--' 30 40 50 60 70 80 90 100 110 120
CLlmm)
d. CL -III LL
, .. HO • <liOm",CL
R"" 0."2
'" o>50mmCL
I"
I 110 ::I > ..
"
30 40 50 60 70 ISO 90 100 110 120
ellmm)
f. CL - V LL
Fig. 17 Relationship between carapace length and somatic lengths
as indices of sexual maturity in male P. po/yphagus
100
90
80
70
Ii: ::J 60 .... « 50 ::;; >-...J 40 ...J « ::J 30 t;j I/)
20 '" • 10
0 0
'" .;, "
Fig.18a
Fig.18 b
--* ----..- ovigerous setae ~Mature ovary -x- mating window -egg brush ~berried females
n=289
'" 0 '" 0 '" 0 '" 0 '" 0 '" 0 "! '" '" ... '7 eo '" 0> '<' 0 0 ~
.;, .;, .;, .;, ~ ";" ~
;;; ;;; ~ ~ ;;; .;, .;, '" '" r- r- eo eo ~
0> 0 0 CL(mmj ~ ~
Size at sexual maturity in female P. po/yphagus (wild) derived from physiological and functional maturity indices
Size at sexual maturity in female P. po/yphagus (captive) derived from physiological and functional maturity indices
80 " 70 R2 .. 0.993
46
.CSOmmCL 40 80 o>60mmCl
" " 30 E E
~ 40 ~ " U " ~ 00
~ > 20 R' = 0.'361 30
16 20
R' = 0.9637 10
10
30
200
180
180
140
E 120
~ 10. " " 80
80
" 2.
J.
Fig. 19
" " " 70 BO
CL(mm)
a. CL- MWC
R' = 0.99
.<GOmmeL
o>SOmmCL
R'= 0.9693
,. 5. •• 7.
CL(mrn)
c. CL -III LL
". ". 12<l
, .. E ~ •• " " > ••
,. 2 •
•
80
30
" 100 30 " 50 80 70 80 " 100
CL(mm)
b. CL - VSL
180
160 R' ... 0.9928
• <50mm CL 140 o:;.50mmCL
120
E 100 ~
" " 80 ~
60
" 20
90 100 J. ,. •• 7 • so .. 100
CL(mm}
d. CL-IV LL
R';; 0.9717
RZ '" 0.9204
.. " .. 7. •• 90 100
CL(mm)
e. CL-V LL
Relationship between carapace length and somatic lengths
as indices of sexual maturity in female P. pofyphagus
'" 80
70
60
E 50 .s ~ '" ..
30
20
10
0
0
250
200
E 150
.s ~ ~
- 100
.0
0 0
Fig. 20
70
60 -M
50 -F
E 40
.s ~ ~ >
30
20
10
0 10 20 30 40 '0 .0 70 80 90 100 0 10 20 30 40 .0 .0 70 80 90 100
CL(mm) CL(mm}
3. CL-MWC b. CL - VSL
250
-M 200 -M
-F -F
E 150
E :r ~
~ 100
50
0
10 20 30 40 .0 60 70 80 gO 100 0 10 20 30 40 '0 60 70 80 90 100
CL(mm) CL{mm)
c. CL -III LL d. CL-IV LL
180
160
-M 140
-F
120
E 100 .s ~
80 ~
> 60
40
20
0
0 10 20 30 40 .0 .0 70 80 90 100
CL(mm)
e.CL-VLL
Comparison of regression lines between carapace length and somatic lengths in male and female P. po/yphagus
-c: Q)
E a. 0 Qi > Q)
'0
'" .,
Q) '0 .. ., If) S8-~8 c: Q) 0 .. Q) Cl ~ c: :::l 08-9L 0 .. ., '0
::!!; Q) If)
~ <1\ 0 SL-~L .c
t "C
!. OL-99 c VI Il'l - '-M -II E .l!l c: S9-~9 E c: - Q)
..J '\: () 0
09-9S ....: ..!!:! ., E
SS-~S c: >--.;:
OS-9v ::J -., E
Sv-~v iii ::J >< Q) VI
0 0 0 0 0 0 0 0 0 0 0 -0 '" CO r- <D Il'l '<t <'"> N .... <1\ .... Q)
.!::! nml'lfW A llVnX3S % en
.... N
Cl u..
100
90 I" <50mm CL
" E 10 g
~ " <
" "
'>50mmCL
R'.0.9836
R2·0.986 •
JO+---__ ---+----~--~--~--~ JO 40 50 50 7D " ..
CL[mm)
a. CL-AWC
45
" • <50mmCL R'·0.9868
·"50mmCL
"
"
'" R''' 0.982
15+---~--__ ~--__ --~----~--_,
100
" ao
7D
E " g " :I ~ "
30
20
10
30 50 .. 7D " .. CL(mm)
c. CL- VSL
R".0.9158
.. <SOmmeL
·>50mmCL ..
R''' 0.8636
o+---~--~--__ --__ --~--~---. 20 30 .. 60 7D .. "
CLlmm)
e. CL-IV LL
" 7D .. <SOmmel R"·0.98 •
• >50 mm CL
" E .s 50
~
R"·0.9634 2O+---__ ----.l--____ --~--~--_,
JO
100
..
.. 7D
.. "
.. GO
CLlmm)
7D
b. CL·MWC
.. <50mm CL R'·0.902 •
• >50mm CL
:
R".0.871
ao to
,o~--__ --~----~--~----~--~ JO
so
7D
GO
JO
JO
.. 50 " CL[mm)
d. CL -III LL
.. <50mmCL
·,.60mmCL
" GO
CL(mm)
f. CL - V LL
7D " to
7D .. ..
Fig. 22 Relationship between carapace length and somatic lengths
as indices of sexual maturity in male T. orientalis
100
90
80
i 70
60
; 50
40
~ 30 0
20
10
0
Fig. 23 a
100
90
80
i 70
60
i 50
40
30 ~ 0
20
10
0
Fig. 23 b
-X-X-X -o--mature ovary
-x- ovigerous setae
--f.3-berried females
n =221
~ ~ ~ Hi Sl III 8 , , \'" 1:: i!O !B Iii
, II!
CL (mm)
Size at sexual maturity in female T. orienta/is (wild) derived from physiological and functional maturity indices
-x- ovigerous setae
--f.3-berried females
Y--"'v--x-x-x-x
n =64
CL (mm)
8 \'" , !R
Size at sexual maturity in female T. orientalis (captive) derived from morphological Land functional maturity indices
100 '" 90 .<50mmCL RI- 0.9661 70 .. <Sammet. R''' 0.7966
'>SammeL '>50mmCL 80
60
70 , , !'. .. e -" ~
~ • < ., " 40
R' = 0.9206 JO
JO
20 JO 40 " 70 " 20
60 20 JO 40 " 60 70 80
CL(mm) CL{mm)
a. CL-AWC b. CL-MWC
" 90
R'=O.7126
40 .. <60mmeL. R2 =0.8036 ... <5Omm CL 80
o>60mmCL • >50mmCL
" , E 10
.§. 30 !'. ~
~ ~
~ :: 60 >
" If = 0.9883
20 50 R' -0.9'18
" 40
JO 40 " " 70 80 JO ., 50 SO 70 80
CL(mm) CL(mm)
c. CL- VSL d. CL -III LL
90 70
1f·0.78S9
80 ... <SOmmeL R'=O.772 ... <!iOmm CL.
o;>ofiOmmCL. 60 ->fiOmmCL
e 70 , !'. !'. " .-~ ~ ~ ., ~ 60 >
40
" Rl .. 0.9665
40 JO
JO 40 " 60 70 80 JO 40 60 80 70 80
CI..\mm) Cl..lmm)
e. CL-IV LL f. CL - V LL
Fig. 24 Relationship between carapace length and somatic lengths
as indices of sexual maturity in female T. orientalis
140 100
90 12<>
-M 80 -M
100 -F 70
E 80 E " ~ ~ " ~ " ~ « ~ 40
40 30
20 20
10
0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100
CL(mm) CL(mm)
3. CL- AWC b. CL -MWC
60 140
50 120
-M
-F 100
40
E E 80
~ 30 ~ ~ ~
!l ~ " 20
40
10 20
0
0 10 20 30 40 " 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100
CL(mm) CL(mm)
c. CL- VSL d. CL-III LL
120 100
90
100 -M 80 -F
80 70
E E 60
E 60 ~ 50 :; ~
~ ~
~ > 40
40 30
20 20
10
0 0
0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 5060 70 80 90 100
CL(mm) CL(mm)
e. CL-IV LL f. CL - V LL
Fig. 25 Comparison of regression lines between carapace length and somatic lengths in male and female T. orientalis
1000 • 900 •
800 Y = 12.531 x - 636.73 R' = 0.9685
0- 700 0 ? 600 -,..
500 .'" "0 c: ::l u 400
" n =47 u. 300
200
100
0 50 60 70 80 90 100 110 120
CL (mm)
Fig. 26 a Relationship between fecundity and carapace Length in P. po/yphagus
70
60
50 0-0 0 :.... 40 ,.. "" "0 c: 30 ::l U
" u.. 20
10
0 50
y = 0.7285x - 19.153 R' = 0.9424
60 70
•
•
n =53
80 90 100 110
CL (mm)
Fig. 26 b Relationship between fecundity and carapace Length in T. orienta/is
Plate VI
l' ! ,~ i
i
" ,
f
f f
,
~/' ,/ ~ ___ ...i .... __ ..... _:~ .... __ ..J
L. eft j
Thoracic and abdominal appendages of P. polyphagus
a. Walking legs - III, IV & V : sub-adult female b. Walking legs - III, IV & V : sub-adult male c. Walking legs - III, Iv & V : adult female d. Setae on dactylus: adult female e. Setae on dactylus: adult male f. Abdominal pi eo pods : sub-adult female g. Abdominal pleopods with ovigerous setae: adult female
Plate VII
04
I
l
d~ ______ "'.~ ...... '.~ r
I
\ \
I J .. ~ . c.t:::!: __
Penile process in male P. po/yphagus
a. Sub-adult male with penile process on coxa of fifth pair
of walking legs
b. Magnified view of penile process (sub-adult male)
c. Mature adult male: penile process with pigmentation
Plate VIII
,
r --.v - r-
4-
. .---" b·
Maturation related changes in ventral sternum in
P. po/yphagus
a. Ventral sternum in sub-adult male
b. Ventral sternum in sub-adult female
c-f. Formation of mating window (w ) in adult female
Plate IX
d,
~.
.... "
:;.... "
• " ~.~-';O::::~ >,
. ~" ~ -. e,
@
,.,;. , ';'/ ... /' " ,
/'
t' 1 ".
F.
Thoracic and abdominal appendages of T. orienta/is
a. Pereiopods -III, IV & V : adult female b. Pereiopod - V : adult male & adult male
~-;~:-: 2 ._z:. :; ---.
.2 t,.
. {'" -......,'
c, Dactylus of V pereiopod : adult male (m ) & adult female (f) d. Abdominal pleopods : adult male e. Abdominal pleopods : sub-adult female f. Abdominal pleopods with ovigerous setae: adult female g. Ovigerous setae on abdominal pleopods
Plate X
~- . .~ ,
" , 1
-' . --- ... ..,...
... ...... b.
,.
Gonopores in T. orientalis a. Male - ventral sternum (s ) with gonopore (g ) on coxa
(c) of V pereiopod b. Enlarged view of male gonopore c. Female - ventral sternum (s ) with gonopore (g) on
coxa (c ) of III pereiopod d. Enlarged view of female gonopore
,c
,It'
.-
,~
~ . ..1';;:...:;;' '--'
"-
. .....:, (
.~~, .. -
) ./
..
3
·,C ,
\ ,. . ~"1~ .. , > •
~ 3 " 2
Plate XI Abdominal pleopods of adult female T. orienta lis with eggs
attached to ovigerous setae
[ Exopod : (ex) Endopod : (en) 1
Plate XII
-~
I j) , .
II J • L 4,
-. j --1
-@
.@ '-. !
, ®,...J
,
l. •
• -c. d, e,
Reproductive system in male p, po/yphagus
a, in situ view of vas deferens showing convoluted proximal part (p) and enlarged distal part (eI)
b, Testis (I) with vas deferens c, Median vas deferens (m) d. Distal vas deferens (eI) e, Ejaculatory duct (e) terminating in extensible penile
process (pp)
1
• .. j
I
c·
r L. ....
Plate XIII T.S. of testis (light micrograph, x400) in early maturing
male P. polyphagus showing spermatogonioa (sg)
and primary spermatocytes (ps) packed in seminiferous
lobules (acini) (a) and seminiferous duct (ei)
a & b anterior testis c. middle testis
d. posterior testis
• - • .J '~~-
, t I
Plate XIII e. T.S. of testis in conjunction with proximal vas deferens
(light micrograph, x400) in early maturing male P.
po/yphagus showing lumen (f) with columnar nucleated
epithelial cells (e ) and connective tissue ( ct)
f. T.S. of testis (light micrograph, x400) in maturing male P.
po/yphagus showing peripheral spermatogonia (sg) and
centrally placed spermatocytes (ps)
Plate XIII T.S. of anterior portion of proximal vas deferens (light
micrograph) in male P. po/yphagus showing lumen (r) with
columnar epithelial lining (e)
g. early maturing stage (x100) h. maturing stage (x100)
i. enlarged view of lumen (x400)
j. wall of posterior vas deferens showing epithelial layer,
(e), muscular layer (m) and connective tissue (c) (x400)
Plate XIII T.S. of anterior portion of distal vas deferens (light
micrograph) in early maturing male P. po/yphagus showing
developing epithelial villi (v) on central typhlosole (t) with
connective tissue (c ). muscular layer (m) and epithelial
layer (e).
k. entire view ofT.S. (x 100)
I. typhlosole with villi and connective tissue (x400)
m. three-layered outer wall (x400)
h.
Plate XIII T.S. of distal portion of distal vas deferens (light
micrograph) in maturing male P. po/yphagus showing
inner glandular epithelial lining (g), typhlosole (t ) and
enlarged lumen (r).
n. entire view of T.S. (x 100)
o. three-layered outer wall (x400)
"p. villi (v) of typhlosole (x400)
Plate XIII
"I r ,.~.
T.S. of distal vas deferens (light micrograph) in adult male
P. po/yphagus showing muscle and connective tissue of
thinner outer wall, glandular epithelium (g), typhlosole (I),
spermatophores (s ), spermatophore wall (matrix secreted
by proximal vas deferens) (m1), matrix secreted by the
typhlosole (m2) and matrix secreted by peripheral
epithelium (m3)
q. entire view of T.S. (x 100)
r. villi (v) of typhlosole (x400)
s & t. spermatophore with spermatophore wall
Plate XIV Spent-recovery stage of adult female P. po/yphagus
ovary, with thick ovarian wall and oocytes in secondary
vitellogenesis stage
Plate XV a. T.S. of ovary (light micrograph. x400) in immature female P. po/yphagus showing the proliferative previtellogenesis phase with germinative zone (gz), primordial gonias (g ) and oogonial eells( 00 )
b. T.S. of anterior portion of previtellogenie ovary (light micrograph, x400) in early maturing female P. po(yphagus showing oogonial eel/s(oo ) and primary ooeytes (oc)
/
• •. __ .~ «-.f
.~..:;- " . .. "" ." .. " I' \ ........ I, ,
t I
e.
Plate XV c. T.S. of previtellogenic ovary (light micrograph, x1000) in early maturing female P. po/yphagus showing the peripheral chromatin nucleoli (n ) and follicle cells (f)
d. T.S. of developing ovary (light micrograph, x400) in primary vitellogenesis phase in maturing female P. po/yphagus showing central germinal zone (gz) and developing oocytes (oc) towards the peripheral region
e. T.S. of developing ovary (light micrograph, x400) in primary vitellogenesis phase in maturing female P. po/yphagus showing packed oocytes (oc) in which yolk deposition has begun
I.
Plate XV T.S. of oviduct (light micrograph) in female P. po/yphagus
showing three-layered wall with outer epithelial layer (e ),
central connective tissue layer (c ) and inner high
columnar epithelium (ce), lumen (r), and villi (v).
j. maturing stage: entire view of T.S. (x100)
k. maturing stage: view of a portion (x400)
I. mature stage : enlarged view (x400 & x6, digital loom)
showing columnar epithelial cells and villi, forming
semi-closed channels (ch )
I.
Plate XV f. I.S. of mature ovary (light micrograph, x100) of female P. po/yphagus in stage I of secondary vitellogenesis phase, showing mature oocytes (oc) in the ovarian cavity
g. I.S. of developing ovary (light micrograph, x400 & x6, digital zoom) in stage II of primary vitellogenesis phase in maturing female P. po/yphagus showing packed oocytes (oc) in yolk platelet stage
h. I.S. of developing ovary (light micrograph, x400) in early maturing female P. po/yphagus showing ovarian wall (ow)
i. I.S. of mature ovary (light micrograph, x400) of female P. po/yphagus in stage I of secondary vitellogenesis phase, showing mature oocytes (oc)
,
,
. j
b· c.
Plate XVI Reproductive system in male T. orientalis
a. in situ view of mature testis (t ) with vas deferens b. Maturing testis with vas deferens c. Ripe testis with vas deferens of sexually active male [ Proximal vas deferens (p ) Distal vas deferens (d) 1
c. d.
Plate XVII T.S. of anterior portion of maturing testis (light micrograph)
in male T. orientalis showing spermatogonioa (sg)
and primary spermatocytes (ps) packed in seminiferous
lobules (acini) (a) and seminiferous duct (d)
a.x100 b. enlarged view of wall (x400)
c. & d. enlarged view of acini with spermatogonia (x400)
, .' t
~.
9· h.
Plate XVII T.S. of distal vas deferens (light micrograph) in adult male·
T. orientalis
e & f. showing typhlosole (t ) and spermatophores (s)
embedded in gelatinous matrix (x 100)
g. enlarged view of typhlosole (x400)
h. gelatinous matrix (x400) ® i. spermatophore with spermatophore wall embedded
in the matrix (x400)
•••
... . , ,
b.
i./.· .. '" 1~ ;: f
~~.
\ I l I
.:1; !
, • I
Plate XVIII Reproductive system in female T. orienta/is
a. in situ view of early maturing ovary (0 ) b. in situ view of late maturing ovary (0)
do.
Plate XIX
t,:,.::::-~;
~1; .) ,.l 1'. ,
" "- \ f , I.':.; ,
:( ·L
rl j", ~ :-- "'-
I i i / I : 1
> ,
I , I
- \ I '!-~ \ ) :% ,
. , I , !
I I
~f .. I a. ,
Development of ovary in female T. orientalis
a. Immature b.& c. Early maturing d.& e. Late maturing f. Ripe g. Spawning [ Oviduct (CJv ) 1
Plate XX a, b. T.S. of anterior portion of ovary (light micrograph, x400) of maturing female T. orientalis in late secondary vitellogenesis stage showing polyhedral shaped mature oocytes (0 ), germinal zone (gz ) and thick ovarian wall (ow)
Plate XX c. T.S. of anterior portion of ovary (light micrograph, x400) of maturing female T. orienta/is in late primary vitellogenesis stage showing maturing oocyte (oc ), with nucleus
d. T.S. of posterior portion of ovary (light micrograph, x400) of mature female T. orientalis showing non-nucleated mature oocytes (oc) and germinal epithelium (ge)
e. T.S. of posterior portion of spent ovary (light micrograph, x400) of female T. orientalis showing resorbed oocytes (oc) and infiltration of connective tissue (ct)
Plate XX f.
g.
h.
i.
T.S. of oviduct (light micrograph, x50) of maturing female T. orientalis showing lumen (() with columnar epithelial cells (ce )
enlarged view of oviduct (x100)
enlarged view of oviduct (x 1 00 & x6, digital zoom), showing columnar epithelial cells
enlarged view (x400), showing columnar epithelium connective tissue (ct ) and oviduct wall (w ) with peripheral oocyte (o )
, 0/ \;i
),~ "
~;-
• c.
1 , ' i
N .. • I I •
N Q
•
Plate XXI a - c Butterfly-shaped spermatophore attachment (s ) on
ventral sternum in female P. polyphagus
[ Dorsal view (d) Ventral view (v) 1
Plate XXI
\
e·
) .-I.J
(
~" ':-
, , " ,
"
.. • •
-~ \
"
" 0 ,
,
\ .itA\ ~ d - e Freshly extruded spermatophoric mass of P.
po/yphagus showing loop-like convolution of the
spermatophore tube
"!F-_1I"
r -" ., ___ ..J
r.\. l If".. • \~
<
, ,
c.
Plate XXII a - c Gelatinous spermatophore mass (s ) on 1st and 2nd
abdominal sternites in female T. orientalis
e.
-".,::- .. ~<t. -, . ~. .
. '''-',.,.. '~.'" " , .#'.
t : r
~.' .•
":'-."'"
.-
,f.
h.
Plate XXII d - e Freshly extruded spermatophoric mass of T. orienta/is, embedded in gelatinous matrix
f. Ruptured spermatophore wall after release of spermatozoa
g. Live spermatozoa inside freshly extruded spermatophore (100 X)
h. Spermatids inside spermatophore in the distal vas deferens (light microscope, x400)
Plate XXIII Ovigerous female P. po/yphagus with fertilized eggs on
pleopods and spermatophore scar on ventral sternum
r. ,
(
. ,
• c. -
, ~-...
. .
;
..." 9' >!
"../, ... {--
Plate XXIV a. Freshly spawned eggs of P. po/yphagus
b. Fertilised eggs attached to ovigerous setae
c. Final stage of embryonic development - Eyed stage
(folded naupliosoma visible inside the eggs)
•
• -,'
;I - -b.
Plate XXV a. Ovigerous female T. orientalis with fertilized eggs on
pleopods
b. Freshly spawned eggs of T. orientalis
I. I • ~ q,. ,
, r
~ .. -c.
r 4 * "
I - '-
Plate XXVI a. Freshly spawned eggs of T. orientalis b. Final stage ova from ripe ovary, with yolk granules c. Early stage of embryonic development d. Eyed stage e. Chromatophore development in embryo f. Final stage of embryonic development
(folded naupliosoma visible inside the eggs)
~.
•
h.
, ~ "' '~ ~ .... '
• ~ , I j
I
\ t ~ ,
, --\_.~
Plate XXVI g. Hatching 9 capsule h. Emptyeg