Form

Kamptozoa average 1 mm in length but can range from 0.1 to 7 mm. The body consists of cup-shaped calyx and is supported by a slender, flexible stalk which attaches basally to the substratum. At the top of the calyx is an encircling tentacular crown of 8 to 30 solid tentacles, which are an extension of the body wall. The space enclosed by the tentacles contains the mouth at the anterior end and the anus at the posterior end. The fact that both the mouth and the anus are located within the central space is where the term Entoprocta is derived, which means “inside anus”. This feature distinguishes them from the Bryozoa which have the anus opening outside the feeding tentacles. The bryozoa are also known as Ectoprocta, meaning "outside anus". The stalk of the kamptozoa is equipped with longitudinal muscle fibers. When these muscle contract it produces the nodding motion of the calyx. Some solitary species are capable of locomotion. This is accomplished by using the sucker at the end of the stalk to glide along the surface, whereas others move by somersault.