Sea Urchins

Sea urchins are spiny, spherical marine animals that inhabit ocean floors worldwide, from shallow waters to great depths. These echinoderms are closely related to sea stars and are known for their hard, calcareous shells, called tests, which protect their soft inner organs.

Sea urchins graze on algae and seagrass, playing an important role in controlling algal growth and maintaining the health of coral reefs. However, unchecked sea urchin populations can overgraze and cause significant damage to ecosystems, particularly when their natural predators are absent.

Despite their simple appearance, sea urchins have a fascinating anatomy, including tube feet and a specialized feeding structure called Aristotle’s lantern. They are also a valuable food source for many marine species and humans, particularly in sushi dishes.