CLASSIFICATION OF ASTACUS (CRAYFISH)
KINGDOM :- ANIMALIA (Multicellular eukaryotic organisms)
PHYLUM :- ARTHROPODA (Jointed appendages.)
SUB-PHYLUM:- CRUSTACEA (Exoskeleton thick, antennae 2 pairs, jaws 3 pairs.)
CLASS :- MALACOSTRACA (6 abdominal segments having body distinctly segmented.)
ORDER :- DECAPODA (Carapace present.)
FAMILY :- ASTACIDAE (Abdomen well developed and hard.)
GENUS :- Astacus (Crayfish)
It is found on the Pacific slope, Europe, Asia, England, U.S.A., Australia and New Zealand.
HABIT AND HABITAT
Astacus is common in streams, rivers and lakes. It is omnivorous feeding on any alive or dead matter. Its acts as scavenger.
GENERAL CHARACTERSTICS OF ASTACUS (CRAYFISH)
- Commonly called as crayfish.
- Body is essentially sub-cylindrical in shape, small, about 9 cm in length and divided into anterior cephalothorax, middle flexible abdomen and posterior telson.
- Cephalothorax comprises of head and thorax and is covered by carapace, which is produced into short and unserrated rostrum and on sides covers the gills. Cervical groove demarcates head and thorax.
- Eyes are stalked, antennules short and antennae elongated.
- Appendages are 19 pairs-5 cephalic, 8 thoracic and 6 abdominal.
- Abdomen contains 6 pairs of swimming appendages or pleopods and a telson.
- Abdominal segments are movable upon one another in a vertical plane. The abdomen is long and extended and ending in tail fans.
- Walking legs are chelate. One pair of legs are called as chelipeds. These are much enlarged appendages, terminating in huge claws or chelate.
- Telson forms a tail-fan together with uropods.
- A. astacus become sexually mature after three to four years and a series of moults, and breed in October and November.
- The main predators of A. astacus, both as juveniles and adults, are mink, eels, perch, pike, otters, and muskrats
- Female carries hundreds of small, rounded eggs on the ventral side of her abdomen. Eggs hatch into young cray-fishes, which are exact replicas of the mother and cling to her for some time.
Economic value :- It is relished as food.
The animal is contains, cephalothorax, cheliped, fan-like uropod and all above features hence it is Astacus.