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A white wave shape.

Sea star

The animal that can regrow a lost arm

It’s true—to a point. Sea stars can regrow a lost arm as long as some part of the central disk, or the middle of their bodies, remains intact. If any of a sea star’s arms are injured, bitten or broken off, tissues at the injury site seal themselves off, then special cells migrate to the area and slowly begin to regrow the arm. This process can take a year or even longer.

At the Aquarium

So happy together

Sea stars are often found in groups—or in close proximity to one another. One reason for this may be because of the way they reproduce, by spawning: females cast eggs into the water, and males cast sperm into the water; it mixes and creates sea star embryos. Sea stars may also feed from the same piece of food, another potential reason that they stay close together.

Quick facts

Sea stars don’t have brains but are still able to detect light!

These creatures bring their stomachs outside of their bodies to eat.

They can regrow a lost arm as long as their central disk remains intact.

Explore More Invertebrates

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Two sea otters at the Seattle Aquarium floating on the water in their habitat, holding onto each other demonstrating a rafting behavior.

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An adult sea otter at the Seattle Aquarium looking upwards with its front paws resting on its front.

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Sea otter at the Seattle Aquarium laying on its back, raising its head and front paws.

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