Sea urchins are commonly found along a rocky ocean floor in both shallow and deeper water, and coral reefs. There are nearly 200 different species of recognized sea urchin, that come in all shapes and sizes.
The main predators of the sea urchin are crabs, large fish, sea otters, eels, birds and humans. The sea urchin mainly feeds on algae on the coral and rocks, along with decomposing matter such as dead fish, mussels, sponges and barnacles.
Sea urchins have a round shaped body with long spines that come off it which are used for: protection, to move about, and to trap food particles that are floating around in the water. The feet of the sea urchin have suckers which help the sea urchin to move about, capture food, and to hold onto the ocean floor.
Sea urchins do not have a brain and instead rely on their water-vascular system– a circulatory system that comprises of water-filled channels which run through the body of the sea urchin.
Due to dredging on the ocean floor and pollution in the water, sea urchin populations are declining and the sea urchin will be threatened with extinction.
