Have you ever tried to prise apart the shell of a mussel or an oyster? It
is practically impossible to do by just pulling, so how does the starfish manage
it using only its tiny feet? The secret is that the starfish again uses its feet
in relays. It hunches itself over the tightly closed shell and attaches its tube
feet to either side. By resting some feet and pulling with others the starfish
is able to exert a strong pull over a long period. and gradually the bivalve
weakens until it gives up the test of strength. Once the valves open a fraction
the starfish turns its stomach inside out and pushes it into the shell to digest
the contents.
