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LARVAL DEVELOPMENT OF THE GHOSTSHRIMP CALLICHIRUS ISLAGRANDE (DECAPODA:THALASSINIDEA: CALLIANASSIDAE) UNDERLABORATORY CONDITIONSAuthor(s): Karen M. Strasser and Darryl L. FelderSource: Journal of Crustacean Biology, 20(1):100-117. 2000.Published By: The Crustacean SocietyDOI: http://dx.doi.org/10.1651/0278-0372(2000)020[0100:LDOTGS]2.0.CO;2URL: http://www.bioone.org/doi/full/10.1651/0278-0372%282000%29020%5B0100%3ALDOTGS%5D2.0.CO%3B2
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In a recent revision of the Callianassidae(Manning and Felder, 1991), the genus Cal-lianassa was restricted from its former world-wide status to certain eastern Atlantic popu-lations based on morphological characters.American species that were previously in-cluded in the genus Callianassa were placedin a number of genera, based on life historyand morphology, as in the case of the genusCallichirus. As redefined by Manning andFelder (1986), the genus Callichirus now in-cludes at minimum C. major (Say, 1818), C.islagrande (Schmitt, 1935), C. seilacheri(Bott, 1955), C. garthi (Retamal, 1975), andC. adamas (Kensley, 1974), and at least oneundescribed species from the Atlantic coastsof Brazil and Colombia which has been of-ten referred to as C. major (see Staton andFelder, 1995; D. L. Felder, personal obser-vation). For a number of other callianassidspecies, generic status remains unresolved,and they will herein be referred to as Cal-lianassa sensu lato (s.l.).
Detailed descriptions of larvae are avail-able for relatively few species in the familyCallianassidae, all of which currently fall intothe subfamilies Callianassinae (Callianassas.l. kewalramanii Sankolli, Sankolli, andShenoy, 1975; Neotrypaea uncinata (H.Milne Edwards), Aste and Retamal, 1984; C.s.l. petalura Stimpson, Konishi et al., 1990),
and Callichirinae (Callichirus sp. (formerlyC. major), Rodrigues, 1976; C. garthi (Reta-mal), Aste and Retamal, 1983; Sergio mirim(Rodrigues), Rodrigues, 1984; Lepidophthal-mus louisianensis (Schmitt), L. sinuensisLemaitre and Rodrigues, Nates et al., 1997;Callichirus major, Strasser and Felder, 1999a).Larval development of Callichirus islagrandehas not been described, even though this spe-cies is well studied (Felder and Griffis, 1994;Staton and Felder, 1995; Strasser and Felder,1998, 1999b).
Callichirus islagrande is a Gulf of Mexicoendemic found typically on barrier islands inlow to high intertidal habitats. This speciesinhabits the northern and western Gulf ofMexico ranging from northwestern Florida toParaiso, Tabasco, Mexico (Staton and Felder,1995). A somewhat discontinuous distribu-tion of C. islagrande occurs between south-eastern Louisiana and the northeastern coastof Texas where shorelines tend to lack thecleaner quartzite sand and high energybeaches that C. islagrande prefers (Staton andFelder, 1995).
The present study describes the zoeal anddecapodid stages, provides illustrations foridentification, and reports the number and du-ration of larval stages of Callichirus isla-grande. Comparisons of these characteristicsin C. islagrande are made with other con-
JOURNAL OF CRUSTACEAN BIOLOGY, 20(1): 100117, 2000
LARVAL DEVELOPMENT OF THE GHOST SHRIMP CALLICHIRUSISLAGRANDE (DECAPODA: THALASSINIDEA: CALLIANASSIDAE)
UNDER LABORATORY CONDITIONS
Karen M. Strasser and Darryl L. Felder
Department of Biology, University of Louisiana, Lafayette, Louisiana 70504, U.S.A.(DLF e-mail: email@example.com); (KMS current address) Box 108F, University of Tampa, 401 W.
Kennedy Boulevard, Tampa, Florida 33606, U.S.A. (e-mail: firstname.lastname@example.org)
A B S T R A C T
Descriptions of the zoeal and decapodid stages of the ghost shrimp Callichirus islagrande werebased on laboratory cultures from a population inhabiting the coast of Louisiana. Whereas mor-phological studies were based upon animals from mass cultures, 40120 larvae from each of 8parental females were reared individually to obtain stage-duration data. Larvae passed through 4 or5 zoeal stages before molting to the decapodid stage. The proportion of individuals that molted toa fifth zoeal stage varied widely (989%) between clutches of different parental females. The firstjuvenile stage was usually reached 1620 days after hatching, and durations of larval stages weresimilar in larvae from different females. Morphological comparisons with congeneric species re-vealed larvae of C. islagrande to be more similar to larvae of C. garthi, a species from the coastof Chile, than to larvae of a Gulf of Mexico population of Callichirus major.
STRASSER AND FELDER: LARVAL DEVELOPMENT IN CALLICHIRUS ISLAGRANDE 101
generic species and members of the familyCallianassidae.
MATERIALS AND METHODSOvigerous females were collected in March, May, and
July, 1996, from the bayward side of a barrier island (IslesDernieres, Louisiana) with yabby pumps (as in Felder,1978). Adult females were maintained in 20-cm diame-ter finger bowls (at 27C, 25 ppt salinity) with daily wa-ter changes until eggs hatched. Sea water was taken fromwell offshore Louisiana, filtered through a 30-m screen,aerated, and diluted to 25 ppt salinity with deionized wa-ter before use in the culture of animals. To determinestage durations, 40120 larvae from each of 8 parentalfemales were reared individually through the first juve-nile stage (J1). ZI (first zoeal stage) larvae were movedto individual compartments upon hatching and maintainedat 27C, in filtered sea water, on a 12:12 light : dark cy-cle. Each day larvae were moved to containers with newsea water, fed freshly hatched nauplii of Artemia (GreatSalt Lake), and examined to assess their stage of devel-opment. Observations were terminated when animalsreached the first juvenile stage (J1).
Animals used for morphological comparisons were ob-tained from mass cultures. Larvae were maintained in 20-cm diameter finger bowls (100200 individuals per bowl)with daily water changes under conditions mentionedabove. Animals were fixed in 70% ethanol, stained withchlorozol black, and transferred to glycerine prior to dis-section. At least 10 animals were dissected for each stage,and both right and left appendages were used for setalcounts. Line illustrations were made on a Nikon invertedmicroscope fitted with a camera lucida. Measurementswere made with a calibrated ocular micrometer. Carapacelength (CL) was measured from the tip of the rostrum tothe posterior midpoint of the carapace, and total length(TL) was measured from the rostral tip to the posteriormidpoint of the telson. For each appendage, the arrange-ment of setae was listed sequentially from proximal todistal margins, as in Konishi (1989) and Nates et al.(1997). Setal groups on successive segments were sepa-rated with a comma (,). Groups of setae on the same seg-ment, or on different lobes of the same segment, article,or endite, were separated with a plus (+). A question mark(?) was used to designate questionable distinctions be-tween setae and aesthetascs. Roman numerals were usedto describe the pattern of processes on the posterior mar-gin of the telson.
Although there was no attempt to quantifythe duration of embryonic development,ovigerous females were held for up to 28 daysbefore the eggs hatched (usually at night).Prior to hatching, eggs changed gradually incolor from bright orange-red to a translucent-brown. Late-stage embryos that were droppedby the female before hatching and larvae thathatched as prezoeae were not viable, evenwith aeration. Prezoeae did not appear to bedeveloped fully and could not swim. All zoealstages fed readily on nauplii of Artemia aswell as on each other. The decapodid stage(D) appeared to consume much less than didthe preceding zoeal stage. Strong positivephototaxis was exhibited by the first threezoeal (ZI to ZIII) stages. The fourth zoealstage (ZIV) in general appeared to be at-tracted to light, although some larvae reactedindifferently. Decapodids did not exhibit ob-vious phototaxis.
Larvae of Callichirus islagrande passedthrough four or five zoeal stages before molt-ing to D (Fig. 1); these were usually com-pleted 1114 days after hatching. Mean du-rations of each stage were relatively consis-tent between larvae from different females(Table 1). However, duration of ZIV was ap-proximately a day shorter when animalsmolted from ZIV to ZV than when animalsmolted directly to D (Table 2). Among theeight cultures observed in this study, the per-centage of animals molting to ZV ranged from989% of the larvae that survived past ZIV.
Description of Zoeal and Decapodid Stages
Near the mandibles, the larval stages anddecapodid had two red chromatophores whichusually appeared fused when expanded. Sev-
Table 1. Mean duration in days (95% CI) of the first to fifth zoeal stages (ZI to ZV), and the decapodid stage (D)in larval cultures from 8 ovigerous females of Callichirus islagrande. Each culture consists of larvae from a differ-ent parental female. Only animals that reached J1 (N) were used to calculate mean durations; N0 is the starting num-ber of ZI larvae.
Culture N N0 ZI ZII ZIII ZIV ZV D
1 100 120 2.26 (0.09) 2.04 (0.05) 2.22 (0.09) 3.88 (0.09) 3.89 (0.12) 5.70 (0.22)2 14 60 2.07 (0.16) 2.00 (0.00) 2.50 (0.31) 3.36 (0.60) 4.30 (0.28) 6.64 (1.17)3 34 55 2.06 (0.08) 2.06 (0.08) 2.44 (0.17) 4.21 (0.24) 4.20 (0.16) 5.68 (0.39)4 102 120 2.05 (0.04) 2.02 (0.05) 2.32 (0.10) 3.59 (0.10) 3.20 (0.09) 5.18 (0.28)5 31 40 2.05 (0.11) 2.00 (0.00) 2.26 (0.16) 3.23 (0.28) 4.00 (0.37) 4.94 (0.23)6 49 60 2.06 (0.07) 2.04 (0.08) 2.43 (0.14) 3.39 (0.20) 3.64 (0.18) 5.47 (0.46)7 36 54 2.17 (0.13) 2.11 (0.11) 2.14 (0.12) 2.94 (0.21) 3.27 (0.15) 4.39 (0.19)8 44 60 2.16 (0.13) 2.25 (0.15) 2.36 (0.17) 3.16 (0.26) 3.42 (0.17) 4.30 (0.30)
102 JOURNAL OF CRUSTACEAN BIOLOGY, VOL. 20, NO. 1, 2000
eral other red chromatophores were presenton the lateral edges of the carapace forminga red line when expanded.
Morphological descriptions of Callichirusislagrande are as detailed below for stages ZIto ZIV, and D. ZV resembled ZIV in appear-ance. However, appendages were like thoseof ZIV, D, or some gradation between thetwo. Setal patterns are given from proximal todistal segments for each appendage. Carapacelength (CL) and total length (TL) are given asthe mean 95% CI in mm, followed by therange of measurements from 10 specimens.
Zoea IFigs. 2a, 3aj
Size.CL = 1.23 0.06 mm, range 1.101.41mm; TL = 3.26 0.07 mm, range 3.113.36mm.
Carapace (Fig. 2a).Shorter than abdomen;rostrum elongate, rounded in cross section,and smooth; eyes fused to carapace.
Abdomen (Fig. 2a).Somites 25 with pos-terolateral projections and posterodorsalspines; dorsal spine elongate on somite 2,sometimes extending beyond posterior mar-gin of somite 3; short dorsal spines on somites35.
Antennule (Fig. 3a).Elongate, exopodal andendopodal lobes not distinct; 46 terminalaesthetascs; 1 long plumose seta on future en-dopodal lobe.
Antenna (Fig. 3b).Protopod with 1 distalspine between rami; endopod with 2 long,plumose setae; scaphocerite (exopod) armedwith 1 strong distolateral spine, 8 plumose se-tae on inner margin, and 1 plumose seta onouter margin.
Mandible (Fig. 3c, d).Incisor process with6 or 7 teeth on right mandible, 57 teeth onleft mandible; molar process denticulate onboth mandibles.
Maxillule (Fig. 3e).Coxal endite with 810marginal setae; basal endite with 3 plumosesetae, 3 or 4 large dentate spines, and 4 or 5smaller dentate spines, inner margin with 0or 1 plumose seta; endopod 3-segmented, dis-tinction between segments sometimes ob-scure, 2, 2, (3 or 4) setae; protopod withoutsetae.
Maxilla (Fig. 3f ).Coxal endite bilobed, 11or 12 setae on proximal lobe, and 4 or 5 se-
Table 2. Percentage of larval Callichirus islangrande that molted from the fourth zoeal stage (ZIV) to the fifthzoeal stage (ZV), or directly to the decapodid stage (D) in larval cultures from 8 ovigerous females (Culture num-bers 18). Each batch consisted of larvae from a different parental female. N0 = number surviving beyond ZIV; N1= number molting ZIV to ZV; N1J = percentage of N1 surviving to J1; N2 = number molting ZIV to D; N2J = per-centage of N2 surviving to J1. The mean duration in days (95% CI) is given for animals that molted from ZIV toZV, and from ZIV to D.
From ZIV To ZV To D
Survived to J1 Duration Survived to J1 DurationCulture N0 N1 N1J of ZIV N2 N2J of ZIV
1 105 11 82 3.0 (0.30) 94 97 4.0 (0.08)2 47 42 24 3.2 (0.23) 5 80 4.4 (1.11)3 45 8 62 3.0 (0.0) 37 78 4.4 (0.18)4 109 10 50 3.1 (0.78) 99 98 3.6 (0.10)5 38 19 79 2.8 (0.26) 19 84 3.7 (0.27)6 58 35 80 3.1 (0.17) 23 91 3.9 (0.30)7 48 30 73 2.6 (0.23) 18 78 3.4 (0.25)8 51 29 83 2.6 (0.19) 22 91 3.8 (0.19)
Fig. 1. Mean proportion of larvae at each stage duringdevelopment of Callichirus islagrande. Mean proportionsare derived from the individual rearings of 8 parental fe-males. The first through fifth zoeal stages (ZI to ZV), thedecapodid stage (D), and all first-stage juveniles thatpassed D (J) are labeled under the peak of each line.
STRASSER AND FELDER: LARVAL DEVELOPMENT IN CALLICHIRUS ISLAGRANDE 103
tae on distal lobe; basal edite bilobed with69 setae on each lobe; endopod with 5 lobes,3+2+2+2+(2 or 3) setae; scaphognathite with1619 setae; all setae plumose.
Maxilliped 1 (Fig. 3g).Coxa with 48 se-tae; basis with 1217 setae; endopod 4-seg-mented, (3 or 4), (1 or 2), (13), (3 or 4) se-tae; exopod 2-segmented, proximal segment
without setae, distal segment with 5 or 6 se-tae on distal margin; bilobed epipod withoutsetae; all setae plumose.
Maxilliped 2 (Fig. 3h).Coxa with 1 or 2 se-tae; basis with 36 setae; endopod 4-seg-mented, (4 or 5), (0 or 1), (1 or 2), (36) se-tae; exopod unsegmented, 68 setae on dis-tal margin; all setae plumose.