WATER BEARS (TARDIGRADA)

S.M. Turk

Morgan & King (1976) list 74 British species, of which six are marine, but O’Reilly (Howson & Picton, 1997) lists 16 marine species. Crothers (1997) follows Shear (1992) in placing the tardigrades, together with other “walking worms” such as the non-British Onychophora within a new phylum, the Lobopodia. Water bears are microscopic creatures 50-1200 microns long, occurring on the surface water of mosses, liverworts and lichens as well in the bottom of standing water. Marine species are mostly to be found between sand grains as part of the interstitial fauna, but they have also been found on algae, mussels and barnacles. Cornish tardigrades have never been studied, and consequently only a few odd records are listed, none of which are rare or have a restricted geographical distribution. This contrasts with the tardigrades of Scotland and Ireland where they have been intensively studied. None are included in the Plymouth area (MBA., 1957).