NATURAL HISTORY
The Phylum urochordata are commonly known as sea squirts. Aristotle (384-322 B.C.) described a simple ascidian and called it Tethym. The adults do not have notochord and the body is covered with the test containing branchial and atrial openings.
Tunicates inhabit sea from polar oceans to the tropics, mostly in shallow shore water, but some upto the depths of 5 km. Some are free living, others after a short free-life attach to rocks, shells, wharf piling or ship hulls. They vary in size from microscopic to a foot in diameter. Variously coloured forms are found. They have about 2000 species, of which 100 are pelagic. Reproduction is sexual and asexual. The group name refers to the self-secreted ‘tunic’ or sac-like covering over the body. The best known tunicates are sea squirts or ascidians.
DIAGNOSTIC CHARACTERS OF PHYLUM UROCHORDATA
- Typically short, thick-bodied, with a leathery covering called test or tunic.
- Notochord and nerve cord present only in larval tail.
- They are marine filter feeders with a water-filled, sac-like body structure and two tubular openings, known as siphons, through which they draw in and expel water.
- Most adult tunicates are sessile, immobile and permanently attached to rocks or other hard surfaces on the ocean floor; others, such as salps, larvaceans, doliolids and pyrosomes, swim in the pelagic zone of the sea as adults.
CLASSIFICATION OF PHYLUM UROCHORDATA
Class 1 :- Ascidiacea
Class 2 :- Thaliacea
Class 3 :- Larvacea
- Minute forms.
- Tunic temporary.
- Gill slits 2.
Example :- Oikopleura
REFERENCES :-
- https://en.wikipedia.org/wiki/Tunicate
- Book of Practical Zoology VERTEBRATE by S.S.LAL – Rastogi Publications.
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ALLIGATORALLIGATOR CLASSIFICATION OF ALLIGATOR PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium with brain present ) ...READ MORE
MUSK DEERMUSK DEER CLASSIFICATION OF MUSK DEER : MOSCHUS MOSCHIFEROUS PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium with ...READ MORE
HEMIDACTYLUS : COMMON HOUSE LIZARDHEMIDACTYLUS : COMMON HOUSE LIZARD CLASSIFICATION OF HEMIDACTYLUS : COMMON HOUSE LIZARD PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( ...READ MORE
SKATE : RAJASKATE : RAJA CLASSIFICATION of SKATE : RAJA Phylum :- CHORDATA ( Notochord and dorsal tubular nerve cord present and gill-slits present). Group :- CRANIATA ( Cranium with brain present ). ...READ MORE
CLARIUS : MAGURCLARIUS : MAGUR CLASSIFICATION OF CLARIUS : MAGUR Phylum :- CHORDATA ( Notochord and dorsal tubular nerve cord present and gill-slits present). Group :- CRANIATA ( Cranium with brain present ). ...READ MORE
LINGULALINGULA CLASSIFICATION OF LINGULA PHYLUM :- BRACHIOPODA (Lophophore contains coiled arms.) CLASS :- LINGULATA (Shell valves without hinge.) ORDER :- LINGULIDA (Pedicel passage formed by both ...READ MORE
GYPS BENGALENSIS : VULTUREGYPS BENGALENSIS : VULTURE CLASSIFICATION OF GYPS BENGALENSIS : VULTURE PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. ...READ MORE
PTEROPUS : BATPTEROPUS : BAT CLASSIFICATION OF PTEROPUS : FRUIT BAT PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium with brain ...READ MORE
MANGOOSE : HERPESTESMANGOOSE : HERPESTES CLASSIFICATION OF MANGOOSE : HERPESTES PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present) Group :- CRANIATA (Definite head. Cranium with ...READ MORE
MACACA MULATA : RHESUS MONKEYMACACA MULATA : RHESUS MONKEY CLASSIFICATION OF MACACA MULATA : RHESUS MONKEY PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite ...READ MORE
