* Tube feet are essential for feeding: Sea stars use their tube feet to pry open clam shells. They grip the shell edges with their tube feet and exert a constant pull. This force is strong enough to overcome the clam's muscle power and open the shell just a crack.
* How they eat: Once the shell is slightly open, the sea star will evert its stomach through its mouth and into the clam's shell. The stomach digests the clam's flesh, and then the sea star retracts its stomach back into its body.
Without tube feet, the sea star wouldn't be able to exert the pressure needed to pry open the clam's shell. They wouldn't be able to access the clam's flesh and wouldn't be able to eat it.
