June 16, 2010


No, it’s not the purple monster from the deep. Or maybe it is. The purple or ochre sea star is common on rock shores and rocks on beaches along the west coast including the Malibu, California coast where I took this photo earlier this morning. This purple sea star (pisaster ochraceus) is on a rock covered by mussels, which is a kind of unfortunate thing for the mussels. The purple sea star is a major predator of California coastal waters, eating all kinds of mussels, barnacles, limpets and snails. 

A sea star opens a mussel by latching on to the mussel’s shell with hundreds of tiny tube feet and then simply tugging with steady pressure until the mussel shell opens. Then the star extrudes its stomach into the opened shell and digests the mussel. A mature sea star will release dozens of millions of eggs when it spawns. The eggs turn into tiny larvae which became part of the sea plankton population as they grow into mature sea stars. Even though most of the larvae are eaten before they grow into mature stars, that still leaves a LOT of purple stars to feed on mussels.

Purple Sea stars are attractive animals (at least I think so), but they are a major pest to mussel and clam gatherers. I remember a story that I heard when I was a kid about how difficult it is to get rid of sea stars. The story goes that clam gatherers were collecting sea stars from the clam beds and trying to kill the stars by cutting them up into two or three pieces and then just throwing the pieces back into the ocean waters. The problem was that sea stars are able to regenerate a lost leg or two. So each piece of sea star thrown back into the waters regenerated into another whole sea star!



Posted by: Seymour Simon

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