The Shape of Life . Ultimate Animal

Digesting Mussels in the Shell: Documenting Echinoderm Behavior - John Pearse & Don Wobber

One of the really fascinating things about echinoderms is that they don't seem to grow old. They can live forever. The only thing that kills a sea star is physical harm or disease. Some sea stars can regenerate their whole body from one part of the ray. How do they do that? -- John Pearse

Starfish stomach inside a mussel shell

Video: Pearse and Wobber film inside a mussel shell as a starfish attacks

Biologist John Pearse has been studying echinoderms along the rugged coast of northern California for forty years. He long believed echinoderms were capable of basic behavior, but he didn't think they were capable of complex social interactions. They don't possess seemingly necessary hardware, like a brain.

But after seeing underwater photographer Don Wobber's time-lapse films of sea stars, Pearse changed his mind. Wobber's footage showed sea stars wrestling with one another to dominate their food supplies on the ocean floor. These animals were certainly capable of leading active lives.

Later filmmakers used a tiny camera embedded inside a mussel's shell to demonstrate how a sea star can exploit a tiny opening in a mussel shell to push its stomach inside. There the stomach can digest the creature right inside its own shell.

"It just goes to show, you don't need eyes, you don't need ears, you don't need to be able to run fast to be a successful organism. You don't even need a brain," says Pearse.

Big Sur, CA
	Dr. John Pearse & Don Wobber Biography and Career Q & A