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How do sea star tube feet help open the shells of oysters and mussels?

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A common comet star and a cushion sea star rest on colorful sponges and seagrass in a vibrant Caribbean underwater scene. — echinoderm Starfishes.

Sea stars (asteroids) utilize their tube feet to prey on shellfish such as oysters and mussels by exerting a continuous, steady pull on the valves of the prey's shell.1

Many sea stars possess tube feet equipped with suckers that provide significant holding power. By attaching these suckers to the shell, the sea star maintains a constant tension. This persistent force eventually causes the muscles that hold the prey's shell closed to tire and relax. Once the valves open slightly, the sea star is able to insert its stomach into the shell to consume the soft tissues inside.12