Pertaining to living things that migrate or rise into the upper surface of water only at night: Bathypelagic organisms, such as pteropods, heteropods, and various crustaceans and siphonophores, are all examples of nyctipelagic organisms that sink from the higher levels to the lower levels of the sea during the day.

Bathypelagic refers to creatures that live in deep water below the level of light penetration, between 1,000 meters and 4,000 meters deep.