Abiotic factors:Cooler temperatures,quite high pressure,no light,water movement the least,save in specific places,A lot of nutrients spewing out from hydrothermal vents( wherever found).

Biotic - very little of food shower comming from upper waters,mostly in the from of decaying ones, invertebrates have thin bodies,44% of deep sea fishes have no eyes,fishes are weirdly shaped,they have various types of bioluminiscent luring organs.Sharks have a suctorial mouth. Sometimes eggs in various stages of development of pelagic fish could be found.In some areas eels & snakes can be seen.