The phylum Entoprocta (also called Kamptozoa) are known as the nicking worm. Globally, 260 species are known to date and 30 in Norway. The individuals are small with a body size of 0.5 – 7 mm. However, besides solitary species, other species build colonies and these can be up to 25 cm in size. Entoprocta occur almost exclusively in marine habitats. Solitary species are epizoic. This means they live on other animals. In contrast, colonies occur on different substrates like stones or algae. The phylum is part of the Lophotrochozoa (also known as Spiralia) and they might be closely related to mollusks like snails and bivalves or moss animals.
These worms look like a wine glass with a ring of tentacles on the edge. The tentacles are used for feeding and the mouth opening is within this ring of tentacles. The area within the ring is also called atrium like the inner courtyard in Roman houses. The mouth is connected to a U-shaped gut and accordingly the anus also opens into the atrium. Hence, the scientific name of the phylum (Ento = inner; procta = anus). The gonads open also into the atrium. The nervous system is not surprisingly for such a small worm not well developed and given the life as sessile feeding organism they have only sensory cilia and no other sensory organs. The tentacles cannot be retracted into the body as it is usual for many other sessile animals. However, they can curl up the tentacles and close the atrium and curled-up tentacles like closing a pouch with a circular string.
The cup is on stalk with muscles and the cup can be bent in relation to the stalk. Hence, the other scientific name (kampto = bend, zoa = animal) and the English name as one can see them nicking all the time. The solitary species are attached to the substrate via an adhesive organ. In contrast, the individuals of the colony are connected to each other at the stalks via a so-called stolon. In this way, they are also attached to the substrate. Both individuals in a colony and solitary organisms can reproduce by budding. Additionally, they can reproduce by sexual reproduction. In this case, they are hermaphrodites. This means they are both male and female at the same time or first male and then female.
