Asteroidea
Class Asteroidea are the sea stars, also called starfish. Most species have five arms that radiate from a central disk, though some have as many as 50. Hundreds of tube feet protrude from the oral surface along radiating channels on each arm called ambulacral grooves. Sea stars move by slowly reaching out their tube feet and pulilng themselves along.
The endoskeleton of sea stars is made of interconnected calcium carbonate plates that form a relatively flexible framework, allowing them to move and bend their arms. The aboral surface is often covered with spines modified into small pincer-like organs called pedicellariae. They help to keep the surface clean.
Most sea stars are predators of bivalves, snails, barnacles and other slow moving animals.
The endoskeleton of sea stars is made of interconnected calcium carbonate plates that form a relatively flexible framework, allowing them to move and bend their arms. The aboral surface is often covered with spines modified into small pincer-like organs called pedicellariae. They help to keep the surface clean.
Most sea stars are predators of bivalves, snails, barnacles and other slow moving animals.