5.—T. R. R. Stebbing, the Challenger and Knowledge of Deep-sea Amphipoda

Abstract

SynopsisThe Reverend T. R. R. Stebbing (1835–1926), who monographed the Challenger Amphipoda, was brought up in a literary and historical tradition, but became a convert to Darwinism and a naturalist about 1860. Canon A. M. Norman was responsible for the Challenger Amphipoda being offered to Stebbing in 1882. Stebbing's monograph, in 1888, describes the collections and contains a lengthy and definitive annotated bibliography of the Order. It also contains the first indication that the Amphipoda have evolved by adaptive radiation governed by Darwinian selection. Stebbing's later work on amphipod taxonomy contains no evolutionary speculation, although his scientific essays were uniformly and sometimes acrimoniously pro-Darwinian.Stebbing treated 63 species of presumed deep-sea benthic gammaridean amphipods. Only 44 of these are now believed to be benthic. The Challenger's gear was inadequate for collection of small abyssal animals, and pelagic species make up an increasingly larger fraction of successively deeper ‘benthic’ samples. Consequently most knowledge of deep-sea benthic Amphipoda comes from work in the last 20 years. A deep-sea transect between Massachusetts and Bermuda has at least 108 species, with a maximum of 85 benthic. Distribution is similar to that of a transect off Oregon. Most of the species are in the families Ampeliscidae, Eusiridae, Lysianassidae, Oedicerotidae, Pardaliscidae, Phoxocephalidae and Synopiidae. There is a marked change of species with depth, categorised in six faunal groupings. Endemism is high in the North American basin and there is little affinity to high latitude faunas. Size and biomass decrease with depth.Diversity of deep-sea Amphipoda is high and comparable to that of Polychaeta and Bivalvia. Present explanations for the high diversity (number of species) are all inadequate in the absence of accurate knowledge of the rate of food supply, diversity of selectively important resources, and rate of food supply, and there is little knowledge of reasons for the high genetic variability in deep-sea animals.