About Starfish(Asteroidea and Ophiuroidea)
Starfish may not be considered a fish, but are animals belonging to the Phylum Echinodermata, and are further divided into two classes Asteroidea (sea stars) and Ophiuroidea (brittle stars). Although starfish are thought to be passive they can be quite a voracious predator under the sea. Starfish feed primarily on mollusks and other echinoderms. While starfish are commonly represented as having only 5 legs, there are some that exhibit many more as seen below.

Here are some of the Starfish:
Sand Sifting Sea Star starfish
Nine Armed or Millipede starfish
Marble Sea Star starfish
Basket Star starfish
Brittle Star starfish
Sunflower Starfish
Red Sea Star starfish
Beaded Star
White Sand Star starfish
hocolate Chip Starfish - Protoreastor nodosus
African Red-Knob Star - Protoreaster lincki
Sand Sifting Star - Astropecten polycanthus
Black Brittle Star
Orange Sea Star starfish
Blue Linckia Sea Star starfish
Brown Star- This starfish various in color from brownish to tan
Common N. Atlantic Starfish
Netted Star
Spiny Beaded Star
Sugar Star
Cushion Star (Bahamas Star)

More about Starfish:
Sea Stars characteristically have five arms extending from a central disk like a star. In the aquarium they can be fed small pieces of fish, placing the food near or even under the Sea Star. Serpent and Brittle Sea Stars are popular additions to reef aquariums that contain live sand as they constantly stir the sand bed and provide oxygen to the beneficial bacteria living in the sand.