Sea Stars (Asteroidea) are sometimes 
called Starfish, even though they are not fish at all.
These animals belong to the phylum Echinodermata, which means "spiny skinned." This phylum is made up of five classes: Asteroidea (sea stars), Echinoidea (sea urchins), Ophiuroidea (brittle stars), Crinoidea (feather stars and sea lilies) and Holothurioidea (sea cucumbers). There are more than 5,000 species and most of them prefer warm waters.
The usual number of arms on these creatures is five but they can have as many as 30. If an arm is broken off, they can grow a new one in its place. Their arms are tipped with suction cups which helps them move along and open their prey which includes clams and other bivalves, sea urchins, and even other sea stars.
A sea star's mouth is on the bottom center where the arms meet.
