Sea Urchins and Sand Dollars: Echinoidea - Physical Characteristics, Behavior And Reproduction, Sea Urchins, Sand Dollars, And People, Long-spined Sea Urchin (diadema Savignyi): Species Accounts - GEOGRAPHIC RANGE, HABITAT, DIET, CONSERVATION STATUS

Sea urchins and sand dollars live all over the world.

HABITAT

Sea urchins live on wave-exposed rocks, in crevices within rocks, in rock pools, on coral reefs, in sandy lagoons, in sea grass beds, and in kelp forests. Sand dollars live in sand and coarse gravel.

DIET

Some sea urchins eat only algae, sea grass, and seaweed. Algae (AL-jee) are plantlike growths that live in water and have no true roots, stems, or leaves. Others also eat small animals and waste particles. Sand dollars eat diatoms and plant particles that accumulate in sand. Diatoms (DYE-uh-tahms) are a type of algae that have a shell.

CONSERVATION STATUS

The World Conservation Union (IUCN) lists one species of sea urchins and sand dollars as Low Risk/Near Threatened, or at risk of becoming threatened with extinction in the future.