National Aquarium – Sea Stars

Sea Stars

DID YOU KNOW?

Sea stars have an amazing ability to regenerate arms when they are severed.

Exhibit Name and Location:
Washington - National Marine Sanctuaries Gallery

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Sea Stars

Sea stars are invertebrates related to sea urchins, sea cucumbers, and sand dollars, which are all echinoderms. Echinoderm means spiny skin, which is a reference to their hard calcified skin. 

Sea stars have an amazing ability to regenerate arms when they are severed, or an arm could potentially grow a new body in some species. 

They have many tube feet extending from the ventral surface. The tube feet allow locomotion via suction created by an internal water-driven hydraulic system.

There are close to 2,000 species of sea stars in the world’s oceans. Most species have five arms, but some have many more.

Diet

Sea stars are mostly carnivorous and prey on mollusks such as clams and mussels. Sea stars digest their prey outside of their bodies by extruding the stomach out of the mouth and enveloping the prey item.

Size

The smallest sea stars are less than an inch in diameter, while the largest sea stars can reach up to 3 feet in diameter.

Range

Sea stars are found in all of the world’s oceans.

Predators

Many different animals eat sea stars, including snails, crabs, shrimp, otters, other sea stars, and birds.

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A Note From the Caretaker

The sunflower sea stars that we have on exhibit have more than 20 arms. With this many arms, they have many more tube feet than a five-armed sea star, which allows sunflower sea stars to move quite quickly.