For other uses, see Las Tunas. Tuna, opah and mackerel sharks are the only species of fish that can maintain a body temperature higher than that of the surrounding tuna patties baked. Found in warm seas, the tuna is commercially fished extensively as a food fish, and is popular as a bluewater game fish. 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.

The following cladogram illustrates the relationship between the tunas and other tribes of the family Scombridae. The “true” tunas are those that belong to the genus Thunnus. Until recently, it was thought that there were seven Thunnus species, and that Atlantic bluefin tuna and Pacific bluefin tuna were subspecies of a single species. The Thunnini tribe also includes seven additional species of tuna across four genera. Bigeye tuna Thunnus obesus showing finlets and keels. The tuna is a sleek and streamlined fish, adapted for speed.

The tuna’s body is countershaded to camouflage itself in deeper water when seen from above, its dorsal side is generally a metallic dark blue while the ventral or under side is silvery or whitish. Tunas achieve endothermy by conserving the heat generated through normal metabolism. In all tunas, the heart operates at ambient temperature, as it receives cooled blood, and coronary circulation is directly from the gills. Also unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red myotomal muscles derive their color from myoglobin, an oxygen-binding molecule, which tuna express in quantities far higher than most other fish. The oxygen-rich blood further enables energy delivery to their muscles. For powerful swimming animals like dolphins and tuna, cavitation may be detrimental, because it limits their maximum swimming speed.

Even if they have the power to swim faster, dolphins may have to restrict their speed, because collapsing cavitation bubbles on their tail are too painful. This section needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Tuna is an important commercial fish. Between 1940 and the mid-1960s, the annual world catch of the five principal market species of tunas rose from about 300 thousand tons to about 1 million tons, most of it taken by hook and line. With the development of purse-seine nets, now the predominant gear, catches have risen to more than 4 million tons annually during the last few years.

Such overfishing has severely damaged bluefin stocks. In recent years, opening day fish auctions at Tokyo’s Tsukiji fish market and Toyosu Market have seen record-setting prices for bluefin tuna, reflecting market demand. It was captured inadvertently using a dragnet. Due to the laws and restrictions on tuna fishing in the United States, federal authorities impounded the fish because it was not caught with a rod and reel. Besides for edible purposes, many tuna species are caught frequently as game, often for recreation or for contests in which money is awarded based on weight. Larger specimens are notorious for putting up a fight while hooked, and have been known to injure people who try to catch them, as well as damage their equipment.