P.E. Tompsett & S.M. Turk

1. Sea-spiders (Pycnogonida)

Pycnogonids resemble small spiders or spider-crabs. In America they are known as “no-body crabs” because the body is very narrow, and the digestive system extends into the tibial articles of the legs. They are all exclusively marine and probably all carnivorous (some are known also to feed on algae). 32 British species have been recorded above 200m (Howson & Picton, 1997); 16 species recorded in the Plymouth area (M.B.A.,1957) and 17 species are listed on the ERICA database. The authors gratefully acknowledge the assistance of R.N. Bamber (formerly of The Natural History Museum).

Achelia hispida

Achelia simplex

Achelia laevis

Endeis charybdaea

Callipallene spectrum

2. Marine mites ( Acari: Halacaridae)

Halacarids are minute, being rarely more than 1mm and mostly under 0.5mm. There are a few British freshwater species, but none as yet have been recorded in Cornwall. There are 54 marine species (Green & Macquitty, 1987), of which 14 species are listed for the Plymouth Marine Fauna (M.B.A., 1957) and 14 species are listed on the ERICA database.

Copidognathus gibbus

Copidognathus loricifer

Copidognathus stevcici