Indication of Cyclic Reproductive Activity in Abyssal Organisms

Abstract

THE difficulty in sampling the sea floor at depths greater than 2,000 m (ref. 1), where the abyssal zone is believed to start², is so great that even today there are not many samples. The yield in specimens from the samples which have been taken is low for any given species of animal and it is seldom that one species has been repeatedly taken. These factors have combined to permit few observations on the biology of any one species. In general, so few ovigerous or gravid specimens of deep sea isopods have been taken that Wolff³ has reasoned that gravid specimens hide in the mud, thus avoiding capture, or that the breeding period is short and occurs once every second or third year. An example of the absence of gravid female specimens can be found in the report by Menzies⁴ on 123 abyssal species of marine isopods representing 447 specimens. In six cases gravid specimens were reported.