This Synopsis covers all eighty-four species recorded at all depths from the north-east Atlantic, east of the Mid-Atlantic Ridge, south of the Wyville Thompson Ridge, and north of the Azores Fracture Zone and of the entrance to the Mediterranean (thus >38°N). Keys to families, genera and species are provided along with notes on species and their distribution. The volume represents a comprehensive revision of British sea spiders (King, 1974), incorporating new information and expanded to include 84 species from 12 families.
The pycnogonids, or ‘sea spiders’ are a class of the phylum Arthropoda with few clear affinities to any other arthropod group. They are exclusively marine and occur from the littoral zone to the abyss and world-wide. Almost all known species from the north -east Atlantic are free-living as adults, although some endoparasitic species are known from elsewhere in the world.