View your list of saved words. (You can log in using Facebook.)
Any of seven species (genus Thunnus, family Scombridae) of commercially valuable food fishes. Species range from the 80-lb (36-kg) albacore to the bluefin tuna (T. thynnus), which grows to 14 ft (4.3 m) long and weighs up to 1,800 lbs (800 kg). Tunas have a slender, streamlined body and a forked or crescent-shaped tail. They are unique among fishes in having a vascular system modified to maintain a body temperature above the water temperature. Though slow swimmers, they migrate long distances over all the world's oceans. They eat fishes, squid, shellfish, and plankton.
This entry comes from Encyclopædia Britannica Concise. For the full entry on tuna, visit Britannica.com.