sea urchin

views updated May 14 2018

sea ur·chin • n. a marine echinoderm that has a spherical or flattened shell covered in mobile spines, with a mouth on the underside and calcareous jaws. Several families and genera and numerous species include the Atlantic purple sea urchin (Arbacia punctulata, family Arbaciidae).

sea urchin

views updated Jun 08 2018

sea urchin Spiny echinoderm animal found in marine tidal pools along rocky shores. Round with long, radiating (often poisonous) moveable spines, its skeletal plates fuse to form a perforated shell. Class Echinoidae.