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a genus of fishes of the family Scombridae. A number of ichthyologists distinguish Thunnidae as a separate family with several genera. The body is elongated and spindle-shaped. The tapering tail has large leathery ridges on all sides. Behind the dorsal and anal fins are several finlets. Members of the genus are distinguished from other fishes by the high development of the cutaneous blood vessels, the lateral muscles of the body, and the dark muscles close to the spine; these adaptations allow the fish to swim rapidly for long periods.
The genus embraces seven species, distributed in tropical and subtropical waters of the Atlantic, Pacific, and Indian oceans. In the USSR an Atlantic subspecies of the bluefin tuna (Thunnus thynnus atlanticus) is encountered in the Black Sea, the Sea of Azov, and occasionally the Barents Sea; it attains a length of 3 m and a weight of 600 kg. An Indo-Pacific subspecies of the bluefin (T. t. orientalis) and, on occasion, the albacore (T. alalunga) are encountered in the Sea of Japan.
Tuna are thermophilic, pelagic school fish that migrate long distances. They feed on small fish, cephalopod mollusks, and pelagic crustaceans. They have great commercial value. Representatives of other genera of the family Scombridae are called little tunnies.
REFERENCESNikol’skii, G. V. Chastnaia ikhtiologiia, 3rd ed. Moscow, 1971.
Zhizn’ zhivotnykh, vol. 4, part 1. Moscow, 1971.
Z. V. KRASIUKOVA