fin, organ of locomotion characteristic of fish and consisting of thin tissue supported by cartilaginous or bony rays. In some fish, e.g., the eel, a single fin extends from the back, around the tail, and along the ventral surface. In the majority of fishes, however, there are one, two, or three dorsal fins, a distinct tail fin, and an anal fin. These are called median, or unpaired, fins. In addition to these unpaired fins, most fish also have paired fins. These are the pectoral fins, placed just back of the gills, and the pelvic, or ventral, fins, variable in position and sometimes lacking entirely. The tail is an important organ of locomotion and the paired fins are used for steering, checking speed, balancing, and for slow movements. An adipose fin (fatty tissue without support) is found behind the dorsal fin in some fish, e.g., the salmon and the catfish. See climbing perch; flying fish.

Suttner, Bertha (Gräfin Kinsky), Freifrau von, 1843-1914, Austrian novelist, known chiefly as an ardent pacifist. Her pacifist novel Die Waffen nieder (1889, tr. Lay Down Your Arms, 1892) had great social impact. Through her subsequent friendship with Alfred Nobel, she influenced him to establish the Nobel Prizes. She was the first woman awarded (1905) the Nobel Peace Prize.

or finback whale or razorback whale or common rorqual

Swift, slender-bodied baleen whale (Balaenoptera physalus) named for the ridge on its back. It is 59–89 ft (18–27 m) long, with a triangular dorsal fin, short baleen, and several dozen grooves along its throat and chest. It is gray, with white on the underparts and on the right side of the lower jaw. It is found in oceans worldwide, in groups of a few to several hundred. It lives in polar waters in summer, feeding on crustaceans and small fishes, and moves to warmer waters in winter to breed. Once commercially valuable, it has been substantially reduced in numbers by overhunting and is now listed as an endangered species.

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