Many marine invertebrates, such as this common sea star (Asterias forbesi) are able to regenerate lost body parts.   Sea stars feed mainly on bivalve mollusks such as mussels and clams.  They wrap their arms around the bivalve and begin to pull, holding on with their suction cup-like tube feet.  A 6" sea star can exert a 12-pound pull.    A 2" cherrystone clam exerts a 10-pound pull to keep its valves closed.  This sea star only needs a 0.1 mm gap in order to feed.  It everts its stomach through its mouth and slips it between the the tiny gap between the mollusk's valves.  Once inside the clam, the everted stomach secretes digestive juices which begin to consume the clam's soft tissues.  The clam soon dies, its valves open wider, and the sea star finishes its meal.

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