Sea stars, also known as starfish, protect themselves against predators by using their leather-like, prickly outer skin as armor, along with a host of additional defense mechanisms. The outer layer of skin is comprised of calcium carbonate plates to protect sea stars against the mouths of predators.

Although there are over 2,000 species of sea stars throughout the world, they all protect themselves in much the same way. In addition to having armor-like skin, many of the species of sea stars are brightly colored to camouflage themselves from some predators and to frighten off others. When this defense mechanism fails, the bony bodies of sea stars are difficult for most predators to bite. If a predator does attack a sea star, the sea star can lose a limb and regenerate a new one. Because the major organs of sea stars are located in their arms, some sea stars can even regenerate an entire body out of a limb. Sea stars firmly attach themselves to objects using suction cups on the underside of their bodies, making it difficult for predators to carry them away. Some sea stars can weigh as much as 11 pounds and grow to over 9 inches in diameter, sprouting between five and 40 arms.