Fin whale

  (Balaenoptera physalus)
Fin whale

Description: : The Fin Whale is long, sleek, and streamlined, with a V-shaped head, which is flat on top. A single ridge extends from the blowhole to the tip of the rostrum (upper jaw). There is a series of 50-100 pleats or grooves on the underside of its body extending from under the lower jaw to the navel. The Fin Whale has a prominent, slightly falcate (curved) dorsal fin located far back on its body. Its flippers are small and tapered, and its fluke is wide, pointed at the tips, and notched in the center.

Its most unusual characteristic is the asymmetrical colouring of the lower jaw, which is white or creamy yellow on the right side and mottled black on the left side. This asymmetrical coloration extends to the baleen plates as well, and is reversed on the tongue.

They have very fine, grey-black, baleen plates that traps very small particles of food. Each side of the upper jaw has 260-480 baleen plates.

Size:: The Fin or Finback Whale is second only to the Blue Whale (Balaenoptera musculus), in size and weight. Adult males measure up to 24-25 m in the northern hemisphere and 26.8 m in the southern hemisphere. Females are slightly larger than males, like any other mysticete. Weight for both sexes is between 50-75 tons.

Behaviour: This whale usually swims in pods of 3-7 whales but larger groups (up to 100 animals) may form at rich feeding grounds or while migrating. Among the fastest of the great whales, it is capable of speed bursts up to 40 km/h leading to its description as the "greyhound of the sea".

Fin Whales are known to leap completely out of the water. The spout is vertical and narrow and can reach heights of 6 m. Fin Whales produce a wide variety of low frequency sounds and may also produce high frequency pulses. They can reach depths of 230 m with ease and remain under for up to 15 minutes.

Distribution: : Fin Whales are found in all oceans of the world, though they seem to prefer temperate and polar waters to tropical seas. Fin Whales are migratory. In general, the spring and early summer are spent in cold, high latitude feeding waters. In the fall populations tend to return to low latitudes for the winter breeding season, though they may remain residences at high latitudes if food resources remain plentiful. Because of the alternation of seasons in the two hemispheres, northern and southern populations never meet in equatorial waters.

Feeding: : Fin whales feed mainly on small shrimp-like creatures called krill or euphausiids and schooling fish. They have been observed circling schools of fish at high speed, rolling the fish into compact balls then turning on their right side to engulf the fish.

Reproduction: Adult males reach sexual maturity at about 6-10 years of age. As in some other whales, sexual maturity is reached before physical maturity. Gestation is 12 months, and calves are believed to be born at 2-3 year intervals. Length at birth is 6-6.5 m and weight is 2 tons. Calves nurse for 6-7 months and are weaned when they are 10-12 m in length. The females give birth to young every two or three years.