Blue Linkia Seastar

Though seastars are typically slow moving, creeping comparatively slowly on hundreds or thousands of tiny tube feet, most seastars are voracious predators of sessile animals such as clams, mussels, corals, sponges and many others (sessile = attached in one place). In many species of seastars, feeding is accomplished by everting the stomach out of the body and onto the seastar's prey, and digestion occurs outside the seastar's body. In the case of seastars that prey upon bivalve molluscs (e.g. mussels and clams), the seastar wraps its arms around the shell of the bivalve, holding tightly with the suctioncup-like ends of its many tube feet, and pulling with remarkable force until the bivalve shells are opened slightly. The seastar then everts its stomach inside the shells of its prey, digesting the soft body inside without ever completely opening the shells.

Needless to say, most species of seastars would wreck havoc in a reef aquarium, but blue Linkia seastars are generally considered to be reef aquarium safe. While there is some debate as to what these seastars actually eat (microbial films and detritus have been suggested as likely candidates), I have observed our Linkia eating several species of sponges, including chicken liver sponges (Chondrilla sp.) and another unidentified sponge. Both of these sponges now grow only in our seagrass tank, which is free of Linkia predation.