Ribbon worm is any of a group of worms with a slender, often flattened body and a long proboscis (snout). The proboscis lies above the mouth and can be thrown out quickly and wrapped around the prey. In some ribbon worms, the proboscis has daggerlike stylets. A ribbon worm has a complete digestive tract, with openings at the mouth and anus. Ribbon worms feed on other worms and mollusks, both living and dead. They are not harmful to people.
Most ribbon worms live in the ocean, but a few live in moist earth and fresh water. They range in size from less than 1 inch (2.5 centimeters) to 90 feet (27 meters) long. Some ribbon worms are brilliantly colored.
See also Circulatory system (Invertebrates); Coelom.
