Sea stars are carnivorous. Members of many species have protrusible stomachs and prey largely on bivalves, such as clams and oysters; they are extremely destructive to commercial oyster beds. The sea star wraps its arms around the bivalve, grips the shell with its tube feet, and opens it by sustained powerful suction. The shell needs to open only about 1/100 in. (0.25 mm). The sea star then extrudes its stomach through its mouth and inserts it inside the shell of the prey, where it digests and absorbs the soft inner tissues.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.