Sea Urchins and Sand Dollars: Echinoidea

Physical characteristics: Pea urchins are one of the smallest urchins. The tiny egg-shaped shell is only about 0.6 inches (1.5 centimeters) long. These urchins are usually grayish green to bright green and have very short spines, which give the animal a velvety texture.

Geographic range: Pea urchins live in the coastal waters of northern Europe.

Habitat: Pea urchins live buried in gravel and sand.

Diet: Pea urchins eat food particles they find in the sand or gravel.

Behavior and reproduction: Scientists know little about how pea urchins behave. These urchins release eggs and sperm into the water, Pea urchins are one of the smallest urchins. The tiny egg-shaped shell is only about 0.6 inches (1.5 centimeters) long. This one is living among the spines of a red heart urchin. (© Andrew J. Martinez/SeaPics.com) where they unite and develop into free-living larvae, which transform into young urchins that grow into adults.

Pea urchins and people: Pea urchins have no known importance to people.

Conservation status: Pea urchins are not considered threatened or endangered. ∎