Tunas achieve endothermy by conserving the heat generated through normal metabolism. Unlike other endothermic creatures such as mammals and birds, tuna do not maintain temperature within a relatively narrow range. For example, bluefin can maintain a core body temperature of 25–33 ☌ (77–91 ☏), in water as cold as 6 ☌ (43 ☏). All tunas are able to maintain the temperature of certain parts of their body above the temperature of ambient seawater. Thunnus are widely but sparsely distributed throughout the oceans of the world, generally in tropical and temperate waters at latitudes ranging between about 45° north and south of the equator. The tuna's dorsal side is generally a metallic dark blue, while the ventral side, or underside, is silvery or whitish, for camouflage. The caudal peduncle, to which the tail is attached, is quite thin, with three stabilizing horizontal keels on each side. Seven to 10 yellow finlets run from the dorsal fins to the tail, which is lunate – curved like a crescent moon – and tapered to pointy tips. It has two closely spaced dorsal fins on its back The first is "depressible" – it can be laid down, flush, in a groove that runs along its back. The tuna is a sleek and streamlined fish, adapted for speed. Finlets are found between the last dorsal and/or anal fin and the caudal fin. They are:īigeye tuna Thunnus obesus showing finlets and keels. The Thunnini tribe also includes seven additional species of tuna across four genera. Thunnus ( Neothunnus) – the yellowfin group For example, the cladogram illustrates that the skipjack tunas are more closely related to the true tunas than are the slender tunas (the most primitive of the tunas), and that the next nearest relatives of the tunas are the bonitos of the tribe Sardini. The following cladogram illustrates the relationship between the tunas and other tribes of the family Scombridae. The cladogram is a tool for visualizing and comparing the evolutionary relationships between taxa, and is read left-to-right as if on a timeline. subgenus Thunnus ( Neothunnus): yellowfin group. subgenus Thunnus ( Thunnus): bluefin group.genus Thunnus: albacores and true tunas.The Thunnini tribe is a monophyletic clade comprising 15 species in five genera: The immediate source for "tuna" in English is Spanish atún < Andalusian Arabic at-tūn, assimilated from al-tūn التون : 'tuna fish' < Greco-Latin thunnus mentioned above. The term "tuna" ultimately derives from Middle Latin Thunnus (from Ancient Greek: θύννος, romanized: thýnnos, lit.'tunny-fish'), which is in turn derived from θύνω ( thýnō), meaning "to rush, dart along". As a result of overfishing, some tuna species, such as the southern bluefin tuna, are threatened with extinction. įound in warm seas, the tuna is commercially fished extensively as a food fish, and is popular as a bluewater game fish. Greatly inflated speeds can be found in early scientific reports and still widely reported in the popular literature. An active and agile predator, the tuna has a sleek, streamlined body, and is among the fastest-swimming pelagic fish – the yellowfin tuna, for example, is capable of speeds of up to 75 km/h (47 mph). Tuna, opah and mackerel sharks are the only species of fish that can maintain a body temperature higher than that of the surrounding water. The Thunnini comprise 15 species across five genera, the sizes of which vary greatly, ranging from the bullet tuna (max length: 50 cm or 1.6 ft, weight: 1.8 kg or 4 lb) up to the Atlantic bluefin tuna (max length: 4.6 m or 15 ft, weight: 684 kg or 1,508 lb), which averages 2 m (6.6 ft) and is believed to live up to 50 years. Tunas (from top): albacore, Atlantic bluefin, skipjack, yellowfin, bigeyeĪ tuna is a saltwater fish that belongs to the tribe Thunnini, a subgrouping of the Scombridae ( mackerel) family.
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