Tuna are several species
of ocean-dwelling fish in the family Scombridae, mostly in the
genus Thunnus. Tuna are fast swimmers and include several species
that are warm-blooded. Unlike most ocean fish species, which have
white flesh, the flesh of tuna is pink. This is because the tuna's
blood has a higher oxygen carrying ability than other fish species.
Some of the larger tuna species such as the bluefin tuna can raise
their blood temperature above the water temperature with muscular
activity. This enables them to live in cooler waters and survive
a wider range of circumstances. Tuna is a popular seafood. Some
varieties of tuna, such as the bluefin, are endangered because
of overfishing, while others are part of well maintained fisheries,
such as the bigeye or yellowfin.
are oftentimes relatively high in tuna, as they sit higher in
the food chain. Because of this, the FDA in March 2004 issued
guidelines recommending pregnant women, nursing mothers and children
should limit their intake of tuna and certain other types of fish.
It is difficult to keep tuna in a captive environment; Monterey
Bay Aquarium is one of the few aquariums in the world that successfully
keep tuna in display.
Above Images Come From The N.O.A.A.