A zone of the ocean between the sublittoral and abyssal, the continental slope, within a depth of 200 lo 3000 m. Its population is poor, existing at the expense of organic matter from the surface layers. Among invertebrates, there are many brachiopods, ten-legged crustaceans, mollusks, echinoderms, and others. Among fish, longtails and charcoal fish are common.
High pressure (up to 25 MN/m² or 250 kgf/cm²).
Almost total absence of light.
Small seasonal temperature variations.
Little seasonal variation in water density.
Water mobility - relatively weak, but much greater than in abyssals.
Bottom topography - dissected.
Seabed sediments are patchy and there are numerous bedrock outcrops.
There is a remarkable diversity in fauna, and in the lower bathyal there are many fish species, which are transitional to abyssal forms.
Vegetation is very poor due to lack of light.