The specific position or function that an organism fills in an ecosystem.

Study of the interactions occurring between organisms and their environments; also used to refer directly to such relationships.

A phenotype resulting from environmental or ecological conditions rather than genetic inheritance.

A biological community comprising interacting organisms plus their physical environment.

A distinct population of a species adapted to occupy a particular habitat due to localised natural selection.

A parasite that lives outside its host. Opposite of endoparasite.

A membrane, paired, bone in the upper jaw, located ventrally on the skull. Some fishes, such as serrasalmids, possess small tooth-like projections known as ectopterygoid teeth on this bone.

Movement of water in the opposite direction to the main current, especially in a circular fashion; a whirlpool.

See oedema.

Object laid by a female bird, reptile, fish, or invertebrate, normally roun or oval-shaped and containing a developing embryo surrounded by nutrient material and a protective case or shell; a female gamete; an ovum.

A species spawning above the bottom which scatters demersal eggs randomly.

Subclass of Chondrichthyes, also known as cartilaginous fishes, that includes the sharks, skates and rays.

Common scale-type. Found in all teleosts, and often separated into cycloid and ctenoid forms.

Method of collecting fishes that uses electricity to stun them, commonly used for sampling populations during scientific surveys. Causes no permanent harm to fishes when carried out properly.

Production of electrical impulses in living organisms or tissues.

Of or relating to production of electricity in living cells, sometimes used to in reference to fishes able to deliver an electric shock.

Sensory organ present in some fishes. Used to detect electrical current.

Having a notched margin or edge. Often used in reference to a caudal fin with a slightly concave shape.

A young, unborn or unhatched organism in the process of development.

Derived from or relating to experimental observation as opposed to theory.