Oceans

Sea Urchins

About

Sea urchins are echinoderms! Echino-what? As larvae, they have two identical halves (lateral symmetry), but as adults, they are round. They have an exoskeleton made of calcium-rich plates over an internal skeleton. Tube feet help them stick to materials and move along using suction—sea urchins even breathe through the skin of their tube feet! Their mouth is protected by cartilage and spines that also help them gather food. They use teeth to eat just about anything they can find, from algae to worms and crustaceans and everything in between!

Size
Varies by species
Live in
Ocean waters around the world
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Food
Algae, coral, plants, small marine animals
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IUCN Red List Status
Many are not evaluated for their extinction risk
Green sea urchin

Conservation

Sea urchins are popular additions to home saltwater aquariums. To protect marine life, choose those that have been cultured by people and not collected wild from the ocean.

WHERE ARE THEY AT THE ZOO?

cropped zoo map showing chimpanzee location
Green sea urchin
Green sea urchin (Strongylocentrotus droebachiensis)

Up to 4 inches across, lives in northern Atlantic and Pacific Oceans plus Arctic Ocean.

IUCN Red List status: Not Evaluated

Slate pencil urchin
Slate pencil sea urchin (Eucidaris tribuloides)

Up to 5 inches long, lives in warm waters of the Atlantic Ocean and Mediterranean Sea.

IUCN Red List status: Not Evaluated