PHYLUM UROCHORDATA

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

PHYLUM UROCHORDATA

Class 1 :- Ascidiacea

  • Sessile tunicates with scattered muscles in tunic.
  • Gill slits numerous.
    Example :- Herdmania, Ascidia, Ciona
CIONA
CIONA

Class 2 :- Thaliacea

SALP
SALP

Class 3 :- Larvacea

  • Minute forms.
  • Tunic temporary.
  • Gill slits 2.
    Example :- Oikopleura
OIKOPLEURA
OIKOPLEURA
OUR POSTS
  • PONGO : ORANG-UTAN
    PONGO : ORANG-UTAN CLASSIFICATION OF PONGO : ORANG-UTAN PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium with brain ...READ MORE
  • MYSTUS SEENGHALAMYSTUS SEENGHALA
    MYSTUS SEENGHALA CLASSIFICATION OF MYSTUS SEENGHALA Phylum :- CHORDATA ( Notochord and dorsal tubular nerve cord present and gill-slits present). Group :- CRANIATA ( Cranium with brain present ). ...READ MORE
  • CHELONE : GREEN TURTLE
    CHELONE : GREEN TURTLE CLASSIFICATION OF CHELONE : GREEN TURTLE PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium ...READ MORE
  • CHILOSCYLLIUM : TRUE DOGFISH​CHILOSCYLLIUM : TRUE DOGFISH
    CHILOSCYLLIUM : TRUE DOGFISH CLASSIFICATION of CHILOSCYLLIUM Phylum :- CHORDATA ( Notochord and dorsal tubular nerve cord present and gill-slits present) Group :- CRANIATA ( Cranium with brain ...READ MORE
  • HIPPOCAMPUS (SEA HORSE)​HIPPOCAMPUS (SEA HORSE)​
    HIPPOCAMPUS(SEA HORSE) CLASSIFICATION OF HIPPOCAMPUS (SEA HORSE)​ Phylum :- CHORDATA (Notochord and dorsal tubular nerve cord present and gill-slits present). Group :- CRANIATA (Cranium with brain ...READ MORE
  • NAJA NAJA : COBRANAJA NAJA : COBRA
    NAJA NAJA : COBRA CLASSIFICATION OF NAJA NAJA : COBRA PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium with brain ...READ MORE
  • MOLOCH (THORNY DEVIL)​ LIZARDMOLOCH (THORNY DEVIL)​
    MOLOCH(THORNY DEVIL) CLASSIFICATION OF MOLOCH (THORNY DEVIL)​ PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present) GROUP :- CRANIATA (Definite head. Cranium with ...READ MORE
  • DRACO : FLYING LIZARDDRACO : FLYING LIZARD
    DRACO : FLYING LIZARD CLASSIFICATION OF DRACO : FLYING LIZARD PHYLUM :- CHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present ) Group :- CRANIATA ( Definite head. Cranium with ...READ MORE
  • MAGELLANIA BRACHIOPODAMAGELLANIA
    MAGELLANIA CLASSIFICATION OF MAGELLANIA PHYLUM :-  BRACHIOPODA  (Lophophore contains coiled arms). CLASS :- ARTICULATA (Shell valves articulate by hinge). ORDER :- TEREBRATULIDA FAMILY ...READ MORE
  • LABEO ROHITA : ROHULABEO ROHITA : ROHU
    LABEO ROHITA : ROHU CLASSIFICATION OF LABEO ROHITA : ROHU Phylum :- CHORDATA ( Notochord and dorsal tubular nerve cord present and gill-slits present). Group :- CRANIATA ( Cranium with brain present ...READ MORE

Leave a Reply