How a Sea Star Gets Its Clam
Clams
shut their shells tightly whenever a sea star comes near.
Scallops snap their shells and flee. Why do these creatures
behave as if the sea star will harm them? After all, the
sea star doesn’t even have teeth. But it is a good
hunter.
The sea star cannot see the animals it hunts, but it can sense where they are. The sea star senses chemicals that are released into the water by its prey. Just as you can follow the smell of a hot apple pie to the kitchen, the sea star can follow the “smell” of a clam, mussel, or oyster.
By the time the sea star finds it, the clam has probably closed its shell tightly. A closed clam is almost impossible to open, but a hungry sea star can do it. It crawls onto the clam shell and attaches itself, using its hundreds of tiny, tube-shaped feet that work like suction cups. And then it pulls. A sea star can pull for hours, even for days.
After a while, the clam gets tired. It opens its shell a tiny bit. Then the sea star does something else that seems almost impossible. It pushes one of its two stomachs inside out through its mouth and into the clam’s shell. Inside the shell, this stomach swallows the clam’s soft body.
Because sea stars have no teeth, they cannot chew. They must make their food soupy before they can eat it. The stomach makes juices that dissolve the clam.
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Never
hug a sea star!
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For final digestion, the sea star sucks the clam soup into its second stomach, which always stays inside its body. Then the sea star crawls away, leaving an empty shell behind.
Although a sea star does not have teeth or claws, it is a tiger of the ocean bottom.
