| Main Sections: Physiology
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Physiology A starfish is a marine animal with thick arm-like extensions protruding from its body. A starfish can have up to 40 extensions, but never less than five. All starfish bodies consist of a round, disk-like body and several arm-like extensions. The mouth is located on the underside of the body. The mouth leads to a bag-like stomach. The stomach has groves that extend from the mouth to the tips of each arm. On each arm are little tube-like feet that aid in walking. In some species of starfish, there are suction cups on the arms as well. Each of the arms has an eyespot. This eyespot doesn't see, but senses light instead. A star fish has no brain. Habitat Starfish are found in shallow waters in the Indian, Pacific, and Atlantic Oceans. They live in kelp forests, sandy ocean bottoms, rocky coast lines, tide pools, and coral reefs. Diet Starfish eat shelled animals, like mussels, oysters, and sea urchins. Once the starfish locates it's, prey it will attach itself to the shell and pry it open. Once the shell is open, the starfish will turn its stomach inside out and put it inside the shell. The stomach will then proceed in digesting the animal inside the shell. When the animal is digested, the stomach returns to the inside of the body and the digested substance is sucked up through one of the arms. Predators Starfish are preyed on by sharks, large bony fish and rays. Large starfish will occasionally eat smaller starfish, too. To escape predators, they can drop arms off. The removed arm will soon be replaced by a new one. Even if the starfish is cut in half, another half replaces the missing one, creating two identical starfish. |