Aspects of the biology of the deep-sea spider crab, Dorhynchus thomsoni (Crustacea: Brachyura)

Pelagic first crab stages of the deep-sea spider crab, Dorhynchus thomsoni , are reported from mid-water samples taken at a variety of localities in the Porcupine Seabight and the Rockall Trough. Some of these samples were from hauls made near the surface over depths of 3000 m or more.
An analysis of these pelagic samples, and of benthic catches of D. thomsoni held by the Institute of Oceanographic Sciences and the British Museum (Natural History), indicate that most females and at least some males undergo the puberty prior to the third crab instar, these individuals therefore probably pass through a total of only three larval and three post-laval instars. There is at least a possibility that some individuals moult after the moult of puberty, unlike any other spider crabs.