S.M. Turk

These small worm-like creatures are useful in characterising water masses, and were the first animals to be used as indicator species. None seem to warrant inclusion in the present work. 19 species (one with two distinct forms and another with three subspecies) are recorded from around the British Isles and north-east Atlantic (Pierrot-Bults & Chidgey, 1988); four species have been recorded in the Plymouth area (M.B.A, 1957) and three species are listed on the ERICA database (ERICA 2008).