Anatomy
D
Dorsal Fin
/ /ˈdɔːrs(ə)l fɪn/ /
Etymology:
From Latin dorsalis - "of the back"
Quick Definition
The fin located on the back (dorsal surface) of a fish, used primarily for stability.
📖 Full Definition
The dorsal fin is a median fin located on the dorsal (upper) surface of a fish. It may be single, double, or triple, and its primary function is to provide stability and prevent rolling. In many species the dorsal fin has also evolved for display, defence (spines), locomotion, or as a lure (illicium in anglerfishes). It is one of the most taxonomically important characters in fish identification.
💡 Examples & Context
The tall, sail-like first dorsal fin of the sailfish (Istiophorus platypterus) can exceed the depth of the fish's body. Surgeon fish bear sharp scalpel-like spines at the base of their dorsal fin.