Fin Whale
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[Photo] A Fin Whale surfaces in the Kenai Fjords, Alaska. Fin Whale (Balaenoptera physalus) photographed in the Kenai Fjords near Resurrection Bay, Alaska. Date 8 August 2003. Author Lori Mazzuca, Lori Mazzuca Fine Art Photography (http://www.lorimazzuca.com/)

The Fin Whale (Balaenoptera physalus), also called the Finback Whale or Razorback or Common Rorqual, is a marine mammal belonging to the suborder of baleen whales. It is the second largest whale and the second largest living animal after the Blue Whale, growing to nearly 27 metres (88 ft) long.

Long and slender, the Fin Whale's body is brownish-gray with a paler underside. There are at least two distinct subspecies: the Northern Fin Whale of the North Atlantic, and the larger Antarctic Fin Whale of the Southern Ocean. It is found in all the world's major oceans, from polar to tropical waters. It is absent only from waters close to the ice pack at both the north and south poles and relatively small areas of water away from the open ocean. The highest population density occurs in temperate and cool waters. Its food consists of small schooling fish, squid and crustaceans including mysids and krill.

Like all other large whales, the Fin Whale was heavily hunted during the twentieth century and is an endangered species. The International Whaling Commission (IWC) has issued a moratorium on commercial hunting of this whale, although Iceland and Japan have announced intentions to resume hunting. Collisions with ships and noise from human activity are also significant threats to the recovery of the species.

Taxonomy
The Fin Whale has long been known to taxonomists, first described by Frederick Martens in 1675 and then again by Paul Dudley in 1725. These descriptions were used as the basis of Carolus Linnaeus' Balaena physalus (1758). The Comte de Lacepede reclassified it as Balaenoptera physalus early in the nineteenth century. The specific name comes from the Greek physa, meaning blows.

Fin Whales are rorquals (family Balaenopteridae), a family that includes the Humpback Whale, the Blue Whale, the Bryde's Whale, the Sei Whale and the Minke Whale. The family Balaenopteridae diverged from the other families of the suborder Mysticeti as long ago as the middle Miocene. However, it is not known when the members of these families diverged from each other. Hybridization between the Blue Whale and the Fin Whale is known to occur at least occasionally in the North Atlantic and in the North Pacific.

As of 2006, there are two named subspecies, each with distinct physical features and vocalizations. B. p. physalus (Linnaeus 1758), or Northern Fin Whale, is found in the North Atlantic, and B. p. quoyi (Fischer 1829), or Antarctic Fin Whale, is found in the Southern Ocean. Most experts consider the Fin Whales of the North Pacific to be a third unnamed subspecies. On a global scale, the three groups rarely mix, if at all.

Description and behaviour
The Fin Whale is usually distinguished by its great length and slender build. The average size of males and females is 19 and 20 metres (62 and 66 ft), respectively. Subspecies in the northern hemisphere are known to reach lengths of up to 24 metres (79 ft), and the Antarctic subspecies reaches lengths of up to 26.8 metres (88 ft). A full-sized adult has never been weighed, but calculations suggest that a 25 metre (82 ft) animal could weigh as much as 70,000 kilograms (154,000 lb). Full physical maturity is not attained until between 25 and 30 years, although Fin whales have been known to live to 94 years of age. A newborn Fin Whale measures about 6.5 metres (21 ft) in length and weighs approximately 1,800 kilograms (4,000 lb). The animal's large size aids in identification, and it is usually only confused with the Blue Whale, the Sei Whale, or, in warmer waters, Bryde's Whale.

The Fin Whale has a brownish grey top and sides and a whitish underside. It has a pointed snout, paired blowholes, and a broad, flat rostrum. Two lighter-coloured chevrons begin midline behind the blowholes and slant down the sides toward the tail on a diagonal upward to the dorsal fin, sometimes re-curving forward on the back. It has a large white patch on the right side of the lower jaw, while the left side of the jaw is grey or black. This type of asymmetry can be seen occasionally in Minke Whales, but the Fin Whale's asymmetry is universal and thus is unique among cetaceans and is one of the keys to making a full identification. It was hypothesized to have evolved because the whale swims on its right side when surface lunging and it often circles to the right while at the surface above a prey patch. However, the whales just as often circle to the left. There is no accepted hypothesis to explain the asymmetry.

The whale has a series of 56 ??? 100 pleats or grooves along the bottom of the body that run from the tip of the chin to the navel that allow the throat area to expand greatly during feeding. It has a curved, prominent (60 cm, 24 in) dorsal fin about three-quarters of the way along the back. Its flippers are small and tapered, and its tail is wide, pointed at the tip, and notched in the centre.

When the whale surfaces, the dorsal fin is visible soon after the spout. The spout is vertical and narrow and can reach heights of 6 metres. The whale will blow one to several times on each visit to the surface, staying close to the surface for about one and a half minutes each time. The tail remains submerged during the surfacing sequence. It then dives to depths of up to 250 metres (820 ft), each dive lasting between 10 and 15 minutes. Fin Whales have been known to leap completely out of the water.

Life history
Mating occurs in temperate, low-latitude seas during the winter, and the gestation period is eleven months to one year. A newborn weans from its mother at 6 or 7 months of age when it is 11 or 12 metres (36 to 39 ft) in length, and the calf follows the mother to the winter feeding ground. Females reproduce every 2 to 3 years, with as many as 6 foetuses being reported, but single births are far more common. Females reach sexual maturity at between 3 and 12 years of age.

Feeding
The Fin Whale is a filter-feeder, feeding on small schooling fish, squid and crustaceans including mysids and krill. It feeds by opening its jaws while swimming at a relatively high speed, 11 kilometres per hour (7 mi/hr) in one study, which causes it to engulf up to 70 cubic metres (18,000 gallons) of water in one gulp. It then closes its jaws and pushes the water back out of its mouth through its baleen, which allows the water to leave while trapping the prey. An adult has between 262 and 473 baleen plates on each side of the mouth. Each plate is made of keratin that frays out into fine hairs on the ends inside the mouth near the tongue. Each plate can measure up to 76 centimetres (30 inches) in length and 30 centimetres (12 inches) in width. The whale routinely dives to depths of more than 200 metres (650 ft), where it executes an average of four "lunges", where it feeds on aggregations of krill. Each gulp provides the whale with approximately 10 kilograms (20 lb) of krill. One whale can consume up to 1,800 kilograms (4,000 lb) of food a day, leading scientists to conclude that the whale spends about three hours of each feeding to meet its energy requirements, roughly the same as humans. If the prey patches aren't dense enough or located too deep in the water, the whale has to spend a larger portion of its day searching for food. Fin whales have also been observed circling schools of fish at high speed, compacting the school into a tight ball, then turning on its side before engulfing the fish.

Behaviour
The Fin Whale is one of the fastest cetaceans and can sustain speeds of 37 kilometres per hour (23 mi/hr, 20 knots), and bursts in excess of 40 kilometres per hour (25 mi/hr, 22 knots) have been recorded, earning the Fin Whale the nickname "the greyhound of the deep". Fin Whales are more gregarious than other rorquals, and often live in groups of 6 ??? 10 individuals, although on the feeding grounds aggregations of up to 100 animals may be observed.

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