Starfish have a unique digestive system with a mouth at the center of their underside and an anus on their upper surface. Food can be brought into the stomach through the mouth or, in many species, the cardiac stomach can be extended out through the mouth to digest food outside the body. They then use their tube feet to pass the food to the stomach.
Some species use their water vascular system to open the shells of some mollusks and inject their stomachs into the shells. It then digests the mollusk in place. Partially digested food is passed to the inside of the starfish where digestion continues in the pyloric stomach. The sea star's arms are filled with digestive glands called pyloric caeca which help with digestion. These digestive glands secrete enzymes and absorb required vitamins from food.
A small intestine runs from the secondary stomach to the anus which is located in the central upper part of the body.
Some species use their water vascular system to open the shells of some mollusks and inject their stomachs into the shells. It then digests the mollusk in place. Partially digested food is passed to the inside of the starfish where digestion continues in the pyloric stomach. The sea star's arms are filled with digestive glands called pyloric caeca which help with digestion. These digestive glands secrete enzymes and absorb required vitamins from food.
A small intestine runs from the secondary stomach to the anus which is located in the central upper part of the body.