A polyp is the sessile form of a cnidarian, with the free swimming form being a medusa. The body is tubular is shape with the mouth located on the upper surface and tentacles surrounding it. The opposite side of the body is attached to a surface. For the hard corals, Scleractinia, the polyp is located within a corallite. The polyp can also detach from the coral skeleton, in a process known as Polyp Bailout.
- (Ruppert Barnes 1994): Ruppert, E.E., Barnes, R.D., Invertebrate Zoology, Saunders College Publishing: Sydney, 1994.