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
OUR POSTS
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APIS INDICA (HONEY BEE)APIS INDICA(HONEY BEE) CLASSIFICATION OF APIS INDICA (HONEY BEE) KINGDOM :- ANIMALIA (Multicellular eukaryotic organisms) PHYLUM :- ARTHROPODA (Jointed appendages.) CLASS :- INSECTA (3 pairs of ...READ MORE
GONIONEMUSGONIONEMUS CLASSIFICATION OF GONIONEMUS PHYLUM :- COELENTRATA (Tissue grade, diploblastic and acoelomate. ) CLASS :- HYDROZOA (The hydroids and craspedote medusa ) ORDER :-TRACHYLINA ...READ MORE
VELELLAVELELLA CLASSIFICATION OF VELELLA PHYLUM :- COELENTRATA (Tissue grade, diploblastic and acoelomate. ) CLASS :- HYDROZOA (The hydroids and craspedote medusa ) ORDER :- CHONDROPHORAE (Float ...READ MORE
LIMAX (GREY SLUG)LIMAX (GREY SLUG) CLASSIFICATION OF LIMAX (GREY SLUG) KINGDOM :- ANIMALIA (Multicellular eukaryotic organisms) PHYLUM :- MOLLUSCA (Unsegmented bilaterally symmetrical and provided with visceral ...READ MORE
TRITURUS CRISTATUS : CRESTED NEWTTRITURUS CRISTATUS : CRESTED NEWT CLASSIFICATION OF TRITURUS CRISTATUS : CRESTED NEWT PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( ...READ MORE
OPHIODERMA (BRITTLE STAR)OPHIODERMA (BRITTLE STAR) CLASSIFICATION OF OPHIODERMA (BRITTLE STAR) KINGDOM :- ANIMALIA (Multicellular eukaryotic organisms) PHYLUM :- ECHINODERMATA (Coelomate, pentaradiate and spiny skinned ...READ MORE
DASYPUS : ARMADILLODASYPUS : ARMADILLO CLASSIFICATION OF DASYPUS : ARMADILLO PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium with ...READ MORE
ANABAS : CLIMBING PERCHANABAS : CLIMBING PERCH CLASSIFICATION OF ANABAS : CLIMBING PERCH Phylum :- CHORDATA ( Notochord and dorsal tubular nerve cord present and gill-slits present). Group :- CRANIATA ( ...READ MORE
MABUIA : SKINKMABUIA : SKINK CLASSIFICATION OF MABUIA : SKINK PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium with brain present ...READ MORE
