CLASSIFICATION OF ASTRANGIA
KINGDOM :- ANIMALIA ( Multicellular eukaryotic organisms)
PHYLUM :- COELENTRATA OR CNIDARIA (Tissue grade, diploblastic and acoelomate. )
CLASS :- ANTHOZOA OR ACTINOZOA (Only polypoid generation. sedentary, solitary, colonial.)
SUB-CLASS :- HEXACORALLIA (Tentacles and mesenteries in multiple of five or six.)
ORDER :- SCLERACTINIA (Stony corals with compact calcareous exoskeleton.)
FAMILY :- RHIZANGIIDAE (Non-reef building corals and reproduce from stolons)
GENUS :- Astrangia
It is found along the coasts of America, Atlantic coasts from North Carolina to North Massachusetts.
HABIT AND HABITAT
Astrangia forms small, encrusting colonies, measuring 5 or 8 cm in diameter on rocks and shells in sheltered places.
GENERAL CHARACTERSTICS OF ASTRANGIA
- Colony consists of closely placed thecae and protruding polyps.
- Polyps (zooids) of the colony are distinct and separated by sclerasepta from theca skeleton of the colony.
- Polyps are usually white, pinkish or greenish and remain expanded during day.
- Oral disc contains mouth, which is surrounded by a double ring of tentacles which are covered with nematocyst warts and tipped with a nematocyst knob.
- Large polyps have three cycles of tentacles mostly 12 larger tentacles alternating with 12 smaller ones.
- Astrangia donae feeds on crustaceans, small fish, and bits of meat.
- Zooxanthellae are absent in the gastroderrnis of the polyps.
The colony consists of closely placed thecae, protruding polyps and all above characters, hence it is Astrangia.