ABSTRACT

By contrast, the floor of the deep sea is home to a community of fish that have adapted to the special conditions of high hydrostatic pressure, low temperature, total absence of sunlight and a sparse food supply. Ashes of the abyss can be divided into a benthic population that inhabits the bottom of the continental slopes, rises, and abyssal plains and secondly, a benthopelagic population roaming the water layers close to the bottom (from 1,000 m to 6,000 m, Marshall and Merrett, 1977; Pinet, 2000). On a gross morphological level, this demersal fish fauna differs remarkably from the mesopelagic community. First of all, most demersal fish are considerably larger than those living at shallower depths in the water column. Further, their coloration, jaw structure, musculature and fin morphology suggest different 'life styles' and adaptations to diverse ecological niches. The pelagic species include many actively swimming fish but the bottom,living population has more passive species, some of which have adopted a sit,and,wait strategy (Merrett, 1987). Food resources in the abyss rely less on local productivity, as in the case of volcanic vent communities, and more on the remains of phyto, and zooplankton and larger organisms such as crustaceans, fish, and mammals (whales) (Pinet, 2000). Among the 84 demersal species recognised in the North Atlantic basin (Merrett and Haedrich, 1997), typical forms include grenadiers (Coryphaenoides), eels and slickheads (Alepocephalids).