A study of the deep-sea lobsters of the families Polychelidae and Nephropidae (Crustacea, Decapoda)

Abstract

The living polychelids consist of three genera and 35 species distributed on the continental slopes and abyssal plains of the world oceans. Six species in the three genera occur in the Gulf of Mexico and Caribbean Sea. Of the 34 or 35 species known in the family Nephropidae, seven species in five genera occur in the deep sea (deeper than 100 fathoms or 183 meters) of the Gulf and Caribbean. This study, centered on the Polychelidae of the world, has revealed that the variability of certain characters (especially the ornamentation of the carapace) in many species is greater than was previously believed. The conservative characters are those which were not stressed by early workers -- the ornamentation of the abdomen and chelipeds. The polychelids are detritus scavengers which probably spend part of their time in the sediments. Several species appear to perform reproductive migrations to shallow depths, where the females release their eggs. These are up to 8500 in number and 0.85 mm in diameter. The deep-sea Nephropidae produce fewer large eggs, 100 to 300 in number up to 3 mm in diameter. Species of both families probably hatch at a zoea stage, although early larval stages of the polychelids are not known. Species of Willemoesia, the abyssal polychelid genus, may metamorphose to the adult stage in the pelagic zone far above the ocean bottom.