CLASSIFICATION OF CEPHALODISCUS

PHYLUM :- HEMICHORDATA (Notochord, dorsal tubular nerve cord present and gill slits present)

CLASS :- PTEROBRANCHIA (Small hemichordates with encased body. V-shaped intestine.)

ORDER :- CEPHALODISCIDA (Solitary or colonial, 2 gill slits, 2 gonads).

FAMILY :- CEPHALODISCIDAE

Genus :-  Cephalodiscus

GEOGRAPHICAL DISTRIBUTION

  • Cephalodiscus is found in antarctic and sub-antarctic region and restricted to archibenthal and sub-littoral zones. It has been reported from India, Japan, Sweden, Borneo, Malayasia, Archipelago and Pacific Ocean.

HABIT AND HABITAT

  • It is a marine colonial animal, found at a depth of 50 to 60 meters. The animal was first discovered by Challanger (1876) at a depth of approximately 245 fathoms in Magellan Strait. Antarctic and Indian oceans have abundant number of this animal.

CEPHALODISCUS

GENERAL CHARACTERSTICS OF CEPHALODISCUS

  • Colony of Cephalodiscus is composed of several unconnected animals, or zooids, which are enclosed in a common case known as coenoecium.
  • Zooids have no organic connections with each other, but they can move freely in the chambers.
  • Zooids are microscopic and differentiated into protosome or cephalic shield, mesosome or collar and trunk. 
  • Protosome or proboscis is flexible and contains heart, buccal diverticulum and the central sinus.
  • Protosome is shield-shaped and continuous with collar, which bears two groups of bilaterally arranged arms which contain tentacles.
  • Trunk is divided into anterior sacciform part, containing alimentation and genital organs, and posterior slender adhesive stalk. Anus is present ventrally. 
  • Digestive tube is V-shaped.
  • Breeding seasonal, sexes are separate. 
  • A sexual reproduction takes place by the budding of the stolon. New individuals detach for free existence but maintaining colonial relationship.
CEPHALODISCUS

SPECIAL FEATURES

  • Zooids or individuals separate but aggregated into a common housing.

IDENTIFICATION

  • The animal has coenoecium and all above features, hence it is Cephalodiscus.
CEPHALODISCUS

REFERENCES

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