any member of the phylum Entoprocta, a group of aquatic invertebrate animals, composed of more than 100 species. Entoprocts occur throughout the world, primarily in marine habitats, although one genus, Urnatella, is a freshwater form. Entoprocts may either exist singly or form colonies of communicating members, called zooids, by budding. The zooids measure only about 0.4 to 5 mm (0.016 to 0.2 inch) in height. Each of them has a stalk (peduncle), which may be jointed, that attaches to shells, seaweed, or to other animals, such as sponges, bryozoans, hydroids, and segmented worms, that produce water currents
Learn more about Entoprocta with a free trial on Britannica.com.