CLASSIFICATION OF CARCINUS (CRAB)
KINGDOM :- ANIMALIA (Multicellular eukaryotic organisms)
PHYLUM :- ARTHROPODA (Jointed appendages.)
SUB-PHYLUM:- CRUSTACEA (Exoskeleton thick, antennae 2 pairs, jaws 3 pairs.)
CLASS :- MALACOSTRACA (Free-living Crustacea with compound eyes, biramous antennules, mandibles, 8 thoracic and 6 abdominal segments having appendages.)
ORDER :- DECAPODA (Carapace present; first three thoracic limbs from maxillipedes.)
FAMILY :- PROTUNIDAE (Flattening of the fifth pair of legs into broad paddles)
GENUS :- Carcinus (The common crab)
It has cosmopolitan distribution and specially found in Europe, U.S.A. and India.
HABIT AND HABITAT
Carcinus is found buried among rocks or mud in shallow water. The crabs are highly specialized crustacean. Breeding season is spring.feeds on a variety of molluscs, worms, and small crustaceans, potentially impacting a number of fisheries.
GENERAL CHARACTERSTICS OF CARCINUS (CRAB)
- Commonly called as Rock crab or True crab.
- Body generally dorsoventrally 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.
- Small antennules, antennae and eye spots are contained in the sockets of the carapace.
- Third maxillipedes are broad flat, valve like covering the other mouth parts on ventral surfaces.
- Five pairs of thoracic legs are well developed.
- 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.
- Abdomen is narrower in male but somewhat broader in female. The abdominal pleura greatly reduced or absent and the abdomen without tailfans.
- Pleopods are greatly reduced. The male has only 2 pairs of pleopods to act as copulatory organ while the female has 4 pairs for the attachment of the eggs. Uropods are absent.
- Females can produce up to 185,000 eggs, and larvae develop offshore in several stages before their final moult to juvenile crabs in the intertidal zone
- Young hatches in the zoaea stage and passes through a megalopa stage before reaching maturity.
The animal contains stumpy abdomen and all above characters, hence it is Carcinus.