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Posted by on Dec 23, 2015 in Tell Me Why |

How Do Sea Stars Eat?

How Do Sea Stars Eat?

In recent years, starfish have been more correctly renamed “sea stars,” because they are not fish. They are echinoderms and related to sand dollars, sea urchins and sea cucumbers.

Starfish eat in a peculiar way. A starfish’s mouth is under its body. These animals have no brain, just a simple nervous system, which relays impulses from arm to arm. Around the mouth is a nerve ring, which connects to radial nerves in each arm.

At the tip of each arm are delicate sensors that detect food or chemicals. It eats by moving on top of its food, and then pushing its stomach out through its mouth until the stomach covers the food and digests it.

Starfish like to eat mollusks, such as oysters and clams. The oyster or clam is protected by two hard shells. Wrapping itself around the mollusk’s tightly clamped shell, the starfish pulls the two halves apart with its powerful arms.

When even the tiniest crack appears, the starfish quickly pushes its stomach through the gap. The clam or oyster inside is done for.

Content for this question contributed by Elisa McArthur, resident of Umatilla, Umatilla County, Oregon, USA