What is "sea urchin"

Sea urchin \Sea" ur"chin\ (Zo["o]l.) Any one of numerous species of echinoderms of the order Echinoidea.

Note: When living they are covered with movable spines which are often long and sharp.

n. Any of many marine echinoderms, of the class ''Echinoidea'', commonly found in shallow water, having a complex chewing structure named Aristotle's lantern.

n. shallow-water echinoderms having soft bodies enclosed in thin spiny globular shells

Sea urchins or urchins , 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. Their roe is a delicacy in many cuisines. The name "urchin" is an old word for hedgehog, which sea urchins resemble.

A sea urchin is a spiny marine echinoderm. "Sea urchin" may also refer to:

• The Sea Urchin (1913 film)
• The Sea Urchin (1926 film)
• The Sea Urchins, an English indie pop band (1986–1991)
• Sea Urchins, a New Zealand television series (1980–84)