The polyp is a sessile form which attaches to the sea floor and often forms large colonies. The polyp structure consists of a basal disc that attaches to a substrate, a cylindrical body stalk, inside of which is the gastrovascular cavity, a mouth opening located on the top of the polyp, and numerous tentacles which radiate out from around the edge of the mouth opening.
Some cnidarians remain a polyp for their entire life, while others pass through the medusa body form. The more familiar polyp cnidarians include corals, hydras, and sea anemones.
