S.M. Turk & P.E. Tompsett
Entoprocts are small, sessile, filter-feeding animals - generally a dissecting microscope is needed to find them - and all are marine except one (not British) and can be either colonial or solitary. The simplest solitary species live in association with various invertebrates, such as sponges, bryozoans or polychaetes and are generally host-specific. The host generates the mutually beneficial water current (Knight-Jones, E.W. & Ryland, J.S. in Hayward, P.J. & Ryland, J.S., 1990). It is certain that many species remain to be described. 45 species are listed by Nielsen (1989) and by Howson & Picton (1997) from British and northeast Atlantic waters in general; nine species recorded in the Plymouth area (M.B.A., 1957); seven species are listed on the ERICA database (ERICA 2008).