CLASSIFICATION OF ASTROPECTEN
KINGDOM :- ANIMALIA (Multicellular eukaryotic organisms)
PHYLUM :- ECHINODERMATA (Coelomate, pentaradiate and spiny skinned animals with vascular system.)
SUB-PHYLUM :- ELEUTHEROZOA (Non-pedicellate and free-living.)
CLASS :- ASTEROIDEA (Central disc and arms fused.)
ORDER :-PAXILLOSIDA (adults lack an anus and have no suckers on their tube feet.)
FAMILY :- ASTROPECTINIDAE (These starfish live on the seabed and immerse themselves in soft sediment such as sand and mud.)
GENUS :- Astropecten
It is found in all parts of the world mostly littoral; New Jersey Southwards; North Carolina Southwards and California.
HABIT AND HABITAT
Astropecten is a large starfish, commonly found in sea below the tide line to great depths. They inhabit sandy bottom where they can burrow. It creeps very slowly on the sea-bottom, but at rest, it lies partly buried in sand with the central part of its body raised into a cone above the sand. A. auranciacus swims 30 to 60 cm per minute
GENERAL CHARACTERSTICS OF ASTROPECTEN
- Commonly called as starfish. Body is star-shaped, consisting of flattened five-pointed central disc with 5 short flexible, triangular arms with tapering tips. Oral and aboral surfaces are distinctly marked.
- Body is covered by a soft transparent skin through which skeleton could be seen.
- Oral surface contains centrally-placed mouth, which communicates with 5 broadly opened ambulacral grooves having double rows or tube feet.
- Mouth is very widely distensible which can swallon bivalves, molluscs, snails and crustaceans very easily.
- Infra-marginal plates are elongated and meet the adambulacral to form the oral surface of the anns. Arms are distinctly marked off from the central disc but do not contain prolongations of either the perivisceral coelom or the gut.
- Mouth is very widely distensible, which can swallow bivalves, molluscs, snails and crustaceans very easily.
- Aboral surface has madreporite in one of the interradii. Skin is soft and somewhat transparent and internal skeleton is seen from outside.
- Aboral surface contains blunt spines, finger-like dermal branchiae and pedicellariae. In some forms spines are absent.
- Sexes are separate. The development includes brachiolaria larva.
The animal contains soft surface blunt spines and all above features, hence it is Astropecten.