Common starfish Common starfish The common starfish or common sea star ("Asterias rubens") is the most common and familiar starfish in the north-east Atlantic. Belonging to the family Asteriidae, it has five arms and usually grows to between 10–30 cm across, although larger specimens (up to 52 cm across) are known. The common starfish is usually orange or brown, and sometimes violet; deep-water specimens are pale. The common starfish is to be found on rocky and gravelly substrates where it feeds on molluscs and other benthic invertebrates. The common starfish normally has five arms, broad at their base and gradually tapering to
Starfish and a smaller pyloric portion. The cardiac stomach is glandular and pouched, and is supported by ligaments attached to ossicles in the arms so it can be pulled back into position after it has been everted. The pyloric stomach has two extensions into each arm: the pyloric caeca. These are elongated, branched hollow tubes that are lined by a series of glands, which secrete digestive enzymes and absorb nutrients from the food. A short intestine and rectum run from the pyloric stomach to open at a small anus at the apex of the aboral surface of the disc. Primitive starfish,