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How does the starfish Asterias eat the soft tissues inside a bivalve shell?

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Two wild horses graze on tall grass in the open prairie of Theodore Roosevelt National Park, with rolling badlands visible in the background. — Feeding behaviour Wild horses graze in the Badlands of North Dakota.

To feed on the soft tissues of a bivalve, a starfish (asteroid) utilizes its tube feet, which are equipped with suckers. The starfish uses these to exert a continuous, steady pull on the valves of the shellfish, such as an oyster or mussel, until the bivalve's adductor muscles tire and the shell opens slightly.1

Once a small gap is created, the starfish extrudes its stomach through its mouth and inserts it into the shell. The soft tissues of the prey are then partially digested externally by the stomach's secretions. After this process, the starfish retracts its stomach, and the remainder of the digestion is completed inside its body.23