Definition of sea urchin in English:

sea urchin


  • A marine echinoderm having a spherical or flattened shell covered in mobile spines, with a mouth on the underside and calcareous jaws.

    Class Echinoidea

    • ‘The sea urchin occupies an important evolutionary position with respect to vertebrates and humans.’
    • ‘The inner shell of a sea urchin is a hollow globe, scored in five curved sections that taper at the ends into a small hole at the top and bottom.’
    • ‘The sea urchin is one of the few marine organisms whose genome has been sequenced.’
    • ‘This sea urchin defends itself with two sets of mobile spines.’
    • ‘The red sea urchin's body is domed above and flat below.’


sea urchin