The bluefin tuna is a pelagic fish, which means that it lives
in deep ocean waters rather than near shallow shores. The largest
species of tuna, the bluefin can grow to a length of 3 m (9.8
ft) and weigh more than 800 kg (nearly 1,800 lb).
As a member fo the tuna family, the bluefin
tuna has a sleek, rounded, streamlined body, tapering to a
narrow junction with
the tail.
It is built
for
sustained
speed.
The pectoral fins fold into grooves on the body, and the eyes
are flush with the body surface. A widely forked tail with
rays extending over the last vertebra provides the driving
force.
On each side of the tail base are bony keels that are extensions
of the caudal vertebrae. The design of the tail and the way
the tendons connect it to the swimming muscles of the body
are unusually
successful. The body design is further improved by the well-developed
vascular system under the skin, which keeps the body temperature
higher than that of the water in which the fish is swimming.
This increases the power output of the muscles and speeds the
nerve impulses. They are distinguished from other fishes
by a series of finlets behind the second dorsal fin and the
anal fin. When hooked, they offer great resistance and are
therefore
popular as game fish. Because the tuna has no respiratory mechanism
to ensure the flow of water over the gills, only the current
caused by its swimming achieves this, so the tuna will die of
anoxia if it stops swimming.1
The bluefin tuna, weighs up to 817 kg (about 1800 lb). It is
found in the Atlantic and Pacific oceans and in the Mediterranean
Sea and is especially abundant off the California coast.1
Habitat of the BlueFin Tuna2
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