Wednesday, 29 February 2012


The trunk bears three openings mouth ,atriopore and anus.The oral hood formed by dorsal and lateral projections of the body. Mouth is formed by margin by oral hood. Atriopore is a small ventral aperture just in front  of the ventral fin. The large atrial cavity surrounding the pharynx opens to outside through atriopore.The anus lies asymmetrically to the left of mid-ventral line at the base of caudal fin. The small posterior body region the anus is the tail.

Tuesday, 28 February 2012


The body of  balanoglossus is divisible into two region the trunk and tail. The anterior end of trunk projects in front as a pointed snout or rosrtum.

Monday, 27 February 2012


Branchiostoma is small elongated narrow fish-like animals 5to 8 cm in size.Body is whitish,like a ''lancelet''.The streamline body is used for burrowing as wellas swimming. The posterior end is tapering and pointed than the anterior end.

Sunday, 26 February 2012


Is marine animal found in shallow waters. It leads a double mode of life . Is a typically ciliary feeder. It feeds in planktonic micro-organisms. Male and female are separate.They release their gametes in water. Development is indirect involving a free-swimming larval stage which gradually assumes the shape of the adult.

Saturday, 25 February 2012


About 9 species of branchiostoma are found.It is more common in Mediterranean sea.The species common in India are Branchiostoma indicum, B.pelagicum and B.ceribbaeum. of all B.lanceolatum is most common.

Friday, 24 February 2012


The branchiostoma is refers to Amphioxus for cephalochordates.The cephalochordata is aiso called as Acrania. The old generic name Amphioxus name ''lancet''OR ''LANCELET'' which are sharp, pointed and lance-like.

Thursday, 23 February 2012


INTRODUCTION- The subphylum Cephalochordata are small,marine,and look like fish.It also called as Lancelet.Pallas in 1778.COSTA in 1834 called as BRANCHIOSTOMA LANCEOLATUM.In 1936 Yarrel called as AMPHIOXUS LANCEOLATUS.

Wednesday, 22 February 2012


House biradially symmetrical,having single aperature.
Pharynx without endostyle.
e.g Kowalevskia.

Tuesday, 21 February 2012


Bilaterally symmetrical.
Pharynx with endostyle.
e.g Oikopleura,Appendicularia.

Monday, 20 February 2012


Small,solitary free-swimming,pelagic neotenic larva-like forms, notochord,nerve cord and brain.
Test forming a temporary.
Atrium and atrial apeerture absent.
Gill-slits 2, opening directly to outside.
Sexes united
No metmorphosis.

Sunday, 19 February 2012


Body barrel-shaped.
Muscle bands form 8 bands.
Gill-slits small.
Tailed larva absent.
Pharynx communicates with atrium.
e.g Salpa, Scyclosalpa.

Saturday, 18 February 2012


Body characteristically barrel-shaped.
Muscle bands incomplete.
Pharynx communicates freely with atrium
Tailed larva absent..
e.g Salpa ,Scyclosalpa .

Friday, 17 February 2012


Colony compact,tubular,phosphorescent in life
Zooids embedded in a common test..
Muscle bands confined to body ends
Gill-slits tall, numerous to 50.
Absent of larval stage.e.g pyrosoma..

Thursday, 16 February 2012


Free -living, pelagic in warm.
Solitary or colonial
Body shape are variable.
Tunic permanent, thin and transparent,having muscle bands.
Atriopore located posteriorly..
Pharynx with 2 large or many gill-slits.
Sexes united.
Larva formed or abesent.
Adult is without notochord.
Asexual budding.
Life history with an alteration of generation.

Wednesday, 15 February 2012


Body is undivided.
Neural gland dorsal or lateral to ganglion.
Gonads is present in mantle wall.
Larva is otolith.
Eye is seperate.
e.g Herdmania, Botryllus ,Molula, Styela.

Tuesday, 14 February 2012


Pharynx with longitudinal vessels.
Budding process. e.g Clavelina.

Monday, 13 February 2012


The pharynx present with longitudinal vessels.
Budding rarely present.e.g  Ascidia, ciona, phallusia.

Sunday, 12 February 2012


Body divided intothorax and abdomen.
Neural gland ventral to ganglion.
Gonads1 in intestinal loop.
Larva with 2 sense organs(ocelli and otolith).

Saturday, 11 February 2012


Solitary,colonial or compound.
Bottom living.
Body form and size variable.
Test permanent,well developed and thick.
Atrium opens dorsally by atriopore.
Pharynx large with many persistent gill-slits.
Sexes united
Larva free-swimming and highly developed.
Stolon simple
Adult sessile after retrogressive metamorphosis
Tail are lost and brain reduced to a dorsal ganglion.

Thursday, 9 February 2012


Tunicata includes nearly,2000 fixed and 100 pelagic species.In 1891 Herdman classified, Lahille1895, perrier 1898,Hartmeyer 1909-1911and S.M Dass in 1957.The subphylum urochordata is divided into three classes.

Wednesday, 8 February 2012


Exclusively marine and cosmopolitan, present in seas depths.
Mostly sedentary,pelagic or swimming.
May be solitary,or colonial.
size 0.25 to 250mm, shape and size.
Having no tail.
Body covered with tunicine similar to celluse so called as tuniacta.
Coelom absent
Notochord present only in larval stage hence called as urochordata..
Alimentry canal complete.
Ciliary feeders.
Respiration through test and gill-slits.
Blood-vascular system open.
Excretion by neural gland, pyloric gland and nephrocytes.
Mostly hermaphrodite.
Fertilization external.
Metamorphosis retrogressive.
Asexual reproduction by budding.

Monday, 6 February 2012


The graptolita were more in ordovician and silurian periods.e.g Dendrograptus .Their tubular chitinous skeleton and colonial habits show an affinity with Rhabdopleura.


It consist small, rounded transparent pelagic larvae,as tornaria larvae called as plactosphaera pelagic.
Alimentary canal is l-shaped.
The larvae body is covered by ciliary bands.

Sunday, 5 February 2012


Solitary or several zooida living unconnected in a commoa gelatinous
Collar with several tentaculated arms.
Gill-slita single pair present.
Gonads single pair present.

Wednesday, 1 February 2012


Colonial,zooids connected by a stolon.
collar with two tentaculated arms.
Gill-slits absent.
Gonads single.
e.g rhabdopleura.