Fin Whales Galapagos Island
The Fin whale (Balaenoptera physalus) is also known as the ‘Finback Whale’ or ‘Razorback Whale’. The Fin Whale is the second largest whale and the second largest living animal after the Blue Whale. Only few sightings have been confirmed. The best place for an observation would be the western archipelago of the Galapagos.
The Fin Whale is found in all the worlds major oceans, from polar to tropical waters. The Fin Whale 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.
Fin Whale Characteristics
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 feet), respectively.
A full-sized adult Fin whale has never been weighed, however, calculations suggest that a 25 metre (82 feet) animal could weigh as much as 70,000 kilograms (154,000 pounds). Full physical maturity is not reached 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 feet) in length and weighs approximately 1,800 kilograms (4,000 pounds). The animals large size aids in identification and it is usually only confused with the Blue Whale, the Sei Whale or 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. The Fin Whale has a large white patch on the right side of the lower jaw, while the left side of the jaw is grey or black.
The Fin 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. The Fin whale has a curved, prominent (60cm, 24 inches) 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. Their spout is vertical and narrow and can reach heights of 6 metres. The Fin 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. Their tail remains submerged during the surfacing sequence. The Fin whale then dives to depths of up to 250 metres (820 feet), each dive lasting between 10 and 15 minutes. Fin Whales have been known to leap completely out of the water.
The Fin Whale is one of the fastest cetaceans and can sustain speeds of 37 kilometres per hour (23 miles per hour) and bursts in excess of 40 kilometres per hour (25 miles per hour) have been recorded, earning the Fin Whale the nickname ‘the greyhound of the deep’.
An adult Fin Whale 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 Fin whale routinely dives to depths of up to 250 metres (820 feet), 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 pounds) of krill. One whale can consume up to 1,800 kilograms (4,000 pounds) of food a day.
Fin Whale Reproduction
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 feet) 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 calves being reported, however, single births are far more common. Female Fin Whales reach sexual maturity at between 3 and 12 years of age.
Fin Whale Diet
The Fin Whale is a filter-feeder, feeding on small schooling fish, squid and crustaceans including mysids (shrimp-like creatures) and krill. It feeds by opening its jaws while swimming at a relatively high speed. Its speed causes it to engulf up to 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. 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.
Fin Whale Behaviour
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.
The highest population density occurs in temperate and cool waters. The Fin whale is less densely populated in the hottest, equatorial regions. It prefers deep waters beyond the continental shelf to shallow waters.
The Fin whales conservation status is classed as ‘endangered’.