However, if eaten ra w, some anemones cause almost certain death. Polyps, Pedal Discs and Planulae Anemones have soft bodies called polyps. Polyps are tubes that have the mouth and tentacles on one end and are sealed on the other. The closed end of the tube is a flattened foot, al so called the pedal disc. The foot attaches to hard surfaces and can also burrow in the sand in certain species.
Some anemones glide along their pedal discs like a snail or move like an inchworm.
Others let go of their rocks and shells and allow themselve s to be carried in the waves. A northern Pacific species does cartwheels to avoid being eaten, although this movement is very slow. Corals have polyps also, as do most cnidarians at some point in their lives. Coral polyps grow connected to each other in large groups called colonies. They also produce a hard, limy skeleton that is the base of coral reefs.