Cancer or Crab

Cancer

Classification :

Phylum  Arthropoda

Class  Crustacea

Subclass  Malacostraca

Order  Decapoda –

Type  Cancer (The common crab)

Habit and habitat : Carcinus is found buried among rocks or mud in shallow water. The crabs are highly specialized crustacean. Breeding season is spring..

Distribution : It has cosmopolitan distribution and specially found in Europe, U.S.A. and India.

:(1) Commonly called as Rock crab or True crab.

 '2) Body generally dorso-ventrally compressed and consist of a large and broad cephalothorax and a stumpy abdomen. Cephalothorax is broader than long. The carapace is fused with epistome at the sides and nearly always in the middle. Rostrum absent.

(3) Small antennules, antennae and eye spots are contained in the sockets of the carapace.

(4) Third maxillepedes are broad flat, valve like covering the other mouth parts on ventral surfaces.

(5) Five pairs of thoracic legs are well developed.

(6) Abdomen is reduced and fixed under cephalothorax. It is permanently bent under the cephalothorax fitting into a groove in the thoracic sterna, thus remaining invisible in the dorsal view of the animal.

(7) Abdomen is narrower in male but somewhat broader in female. The abdominal pleura greatly reduced or absent and the abdomen without tailfans.

 (8) Pleopods are greatly reduced. The male has only 2 pairs to ct as copulatory organ while the female has 4 pairs for the attachment of the eggs. Uropods are absent.

(9) Young hatches in the zoaea stage and passes through a megalopa stage before reaching maturity.