Dorsal fin

File:Aileron de requin.jpg

Dorsal fin of a shark

A dorsal fin is a fin on the back of most marine and freshwater vertebrates.

The main function of the fin is to stabilize the animal against rolling and to help sudden turns. There are some secondary functions: some fish have dorsal fins which produce venom at the tip, for example, the spiny dogfish.

Functions

Some species have further adapted their dorsal fins to other uses.