Common sea star

Common sea stars eat mostly oysters, scallops, mussels, whelks and winkles. It can eat up to 10 mollusks in 24 hours.

The sea star’s meal is a lengthy process. It first has to grip the mollusk using its hundreds of suction-cup feet. A long tug-of-war then begins. The sea star exerts pressure, forcing the mollusk to slightly open its shells. No matter how hard the bivalve tries to stay closed, at some point, muscle fatigue prevents it from continuing to resist the hydraulic force of the sea star’s ambulacral system.

All it takes is for the mollusk to slightly open its shells for the sea star to insert its stomach into the shell and starts digesting it on the spot. When digestion is complete, the stomach returns to its original position.