The word demersal describes things that are on, near, or likely to sink to the bottom of a body of water. It could be used to describe bottom-dwelling fish, nets used for trawling, or seafloor-adjacent zones of the ocean.
Demersel comes from the Latin de, meaning "down," and mergere, meaning "plunge." The word literally means "plunge down," which describes where you must go to find demersal organisms. Demersal fish are any species that live and feed near the bottom of a sea or lake. You may know these fish better than you think: Many popular food fish, such as cod, hake, and halibut, are demersal fish.