Longfinned

Longfinned is an English adjective used to describe animals that have elongated fins relative to related forms. In common usage, the term appears in the vernacular names of several aquatic species, particularly fish and certain marine mammals. It is not a formal taxonomic category; rather, it signals a distinguishing morphological feature used for identification.

In fishes, longfinned names appear in both widely used and local names. The longfin tuna, also known as albacore (Thunnus alalunga), has proportionally longer pectoral fins than many other tunas. The longfin eel (Anguilla dieffenbachii) of New Zealand is notable for its extended dorsal and anal fin rays that run along much of the body, contributing to its distinctive silhouette and long migratory life history.

In marine mammals, the term occurs in the common name of the long-finned pilot whale (Globicephala melas), a large cetacean found in temperate waters of the North Atlantic and North Pacific. It is contrasted with the short-finned pilot whale (Globicephala macrorhynchus). The two forms represent a case where fin morphology correlates with size and ecology.

In other contexts, longfinned or long-finned variants may refer to ornamental or aquarium species with elongated fins, including certain damselfish and other reef fishes, where longer fins are a notable feature but do not define a strict taxonomic group.

See also: longfin, fin morphology, fish common names.