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Sea urchin

Sea urchins or urchins (/ˈɜːrɪnz/), archaically called sea hedgehogs, are small, spiny, globular animals that, with their close kin, such as sand dollars, constitute the class Echinoidea of the echinoderm phylum. About 950 species of echinoids inhabit all oceans from the intertidal to deep. The shell, or "test", of sea urchins is round and spiny, typically from across. Common colors include black and dull shades of green, olive, brown, purple, blue, and red. Sea urchins move slowly, feeding primarily on algae. Sea otters, starfish, wolf eels, triggerfish, and other predators hunt and feed on sea urchins. The name "urchin" is an old word for hedgehog, which sea urchins resemble.

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Original Photo by Cheyenne Tessier. About to eat sea urchins on the Ile de la Madelaines, Senegal.

Contributed by Cheyenne Tessier

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