Protochordata
Protocordata Presenters;Yanuar saputra (130210103001)Indah
Suciati (130210103051)Silvi Anggraeni (130210103058)
Phylum-Chordata
Subphyla
Protochordata( Acrania)
Subphyla
Vertebrata (Craniata)
hemichordata
Urochordata
Cephalochordata
Enteropneusta
Pterobranchia
Graptolites
Larvaceae
Ascidiacea
Thaliacea
Phylum chordata
Phyla chordates is part of the kingdom animalia characterized
having notochorda as the axis of the body. Notochorda is a a stem
structure that serves to propping the body when it has formed
perfectly and help the movement of
Protochordata
The name Protochordates literally means 'the first chordates.
Protochordates a heterogeneous group of animals of phylum Chordata,
related to the vertebrates, which they resemble in possessing gill
slits, noto-chord, and dorsal hollow nerve cord, or at least traces
of these. Protochordates are marine animals `
Why are the protochordates so primitive
Chordates showing primitive features are collectively grouped as
protochordates.
Have a notochord, which is an elongate, stiff, fleshy structure
running down the length of the body, giving structure to the body,
enough so that muscles can fire down the body enechelon to form the
familiar "wiggly" swimming motion of fish.
The notochord is modified into the vertebral column in
vertebrate chordates
The nervous system is of a primitive nature, lying beneath the
body wall. Including a dorsal (toward the top of the body) nerve
cord, which is known as the spinal cord.
Formed in the embryo by an invagination of surface ectoderm
whose original function was probably sensory reception.
Why are protochordates not classified as true Chordata
Like the remaining subphylum of the chordates, the Vertebrata,
the protochordates have a hollow dorsal nerve cord, gill slits, and
a stiff supporting rod, the notochord, the forerunner of the
backbone. The protochordates differ chiefly from the vertebrates in
not having a backbone.
General characteristics of protochordata
Exclusively marine.
Relatively small sized animals
Cranium or brain box, jaws, vertebral column and paired
appendages are absent.
Dorsal tubular nerve cord, gill slits and notochord are usually
present.
Sexes may be separate or united.
Solitary, colonial, free living, pelagic, burrowing or tube like
living forms
1. Hemichordata
The name Hemichordata refers to the presence of a short
notochord, reduced to half the size (hemi half; chorde cord). This
structure is present in the anterior region of the animal, the
proboscis. They include two groups;
Enteropneusta
Pterobranchia
Graptolites
General Characteristics of hemichordates
Exclusively marine and soft-bodied forms
Body is divisible into proboscis, collar and trunk
Notochord occurs only in the anterior end of the body.
Numerous paired gill slits are present.
Nervous tissues lie embedded in the epidermis and occur both on
the dorsal and ventral surfaces.
Coelom is divided into three regions namely protocoel, mesocoel
and metacoel.
Fertilization is external.
Class I- Enteropneusta
Solitary and burrowing worm-like marine forms commonly known as
acorn or tongue worms.
vegetation; filter-feeders
They have well-developed gill slits
Epidermis is ciliated and glandular.
Alimentary canal is straight with a terminal anus.
Two rows of caecae are present in the middle of the trunk.
They have a dorsal strand of nerve cells
Examples of Enteropneusta
Acorn Worm
Class II- Pterobranchia
Sedentary, solitary or colonial and marine forms.
Bears a ciliated tentacles to produce a Ciliary feeding currents
of water.
One pair of gill slits or none.
There is no trace of dorsal nerve cord or notochord
Alimentary canal is U-shape with dorsal anus situated near the
mouth.
Gonads are few in numbers.
Reproduction by budding.
2. Urochordata
Urochordata is the term used to refer to the presence of a
notochord in the tail region, (uro=a tail; chorde=cord).
The notochord is restricted to the tail region of the larval
forms of urochordates and is absent in the adults.
Tunicata is the other name of this subphylum Urochordata, due to
the presence of an outer leathery covering called tunic or test in
the adult (tunica outer covering).
General characteristics of Urochordata
Exclusively marine and commonly known as sea squirts.
Solitary or colonial
Body is covered by a cuticular tunics or test in adult
stage.
Notochord is present in larval stages and absent in adults.
Dorsal tubular nerve cord is present in the larval forms while
degenerates in the form of small ganglion in adults.
A numerous gill slits are present.
Sexes are united that is hermaphrodite.
Heart is ventral, simple and tubular.
Class I- larvacea
Free swimming pelagic forms
Neotenic forms which retain the larval form throughout adult
life.
Posterior part of the body takes the form of a large locomotory
appendage, the tail.
Single pair of gill slits are present
Anus opens ventrally on the surface of the body
Hermaphrodite
No metamorphosis.
Examples of Urochordata
Oikopleura
Class II- Ascidiacea
Fixed or free swimming marine forms
Simple or compound, solitary or colonial.
Locomotory appendage or tail are absent in adults
No traces of notochord
Branchial sac is large and well developed with its walls
perforated by numerous gill slits.
Reproduction is both asexual and sexual
Class III appendicularia
his life in the pelagic, and swim freely
having two slits gills
his body gelatin containing
not having the atrium
the tail is not reduce her adult in phase
Class IV- Thaliacea
Free swimming pelagic forms.
Solitary or colonial
Musculature of the body wall is in the form of circular
bands.
Branchial sac has either two large or many small gill slits.
Tail and notochord are absent in adult.
Life history exhibits an alternation of generations.
DoliolumPyrosoma atlanticum
Cephalochordata
The term Cephalochordata refers to the notochord that extends
the entire length of the body up to the head region (cephalon head;
chorde cord).
The notochord lies on the mid dorsal region just above the
alimentary canal and below the nerve cord.
General characteristics
Exclusively marine and solitary forms
Notochord and nerve cord extend the entire length of the
body.
Notochord, nerve cord and pharyngeal gill slits remain
throughout life of the animal.
Limbs or paired fins are absent.
Mouth is ventral and anterior, while anus is ventral and
posterior.
.
No distinct head but tail present; mouth surrounded by
tentacles
Exoskeleton, head, brain, auditory organs and jaws are
absent.
Sexes are separate
Branchiostoma lanceolatum
