What Is the Order of a Sea Urchin?

Sea urchins are in the order Diadematoida. They belong to the family Diadematidae and to the class Echinoidea. They are spiny spherical, nocturnal animals that graze on plants on the bottom of the ocean.

  1. Habitat

    • An urchin is on the bottom feeding.

      The sea urchin spends its entire life on the bottom of the sea. Urchins inhabit the shallows to the very deepest corners of the ocean.

    Varieties

    • Green sea urchin

      There are more than 900 varieties of sea urchins. Brown, purple, red and green are their common colors.

    Defense

    • Sea urchins are covered in spines for protection. Some of the sea urchins employ poison and inject it through their spines.

    Food

    • Their mouths are a hard beak-like structure underneath their body. Urchins eat algae, kelp, small invertebrates and other plant material.

    Classification

    • Skeleton of sea urchin

      Sea urchins are invertebrates with no brain. They have a hard exoskeleton underneath their spines made up of calcium carbonate, which is similar to the makeup of sea shells.