Urchins use their short spines on the bottom, like hundreds of tiny legs, to walk. The long upper spines are for protection, like an underwater porcupine. Spines also come in handy for burrowing and trapping food. Extending from between the spines are suction-cupped appendages called tube feet. Kelp is the red sea urchin's favorite food.
Urchins also have pincher-tipped grabbing arms called pedicellariae.
These look like miniature pliers and are used to keep the body surface free of debris. Their mouth is located underneath. The teeth come together like the beak of a bird and scrape off a seaweed snack. Urchins usually are found in crevices or rounded depressions in the rock created by years of chewing and grinding. Here they are protected from wave action and most predators.