Organs of propulsion in fishes. In bony fishes - Teleostei - consisting of bony fin-rays, joined by the fin membrane, forming the fin blade. Typically there are a pair each of pectoral fins: P, and pelvic fins: V, and the unpaired fins: the dorsal fin: D, the anal fin: A, both of which in Osteoglossomorpha are single fins; in other families D and A may be subdivided into two or three portions. Gymnarchus has lost both the pelvic fins; the caudal and the anal; the pectoral is rather short, the dorsal fin is the only means of propulsion, but works strikingly well in both directions.
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Alternative form for fins : fin.