The blue whale is the largest animal ever to live on earth - even larger than the dinosaurs, weighing up to 180 tonnes or more. It is slow reproducing and long lived, with a life span of at least 80 years, probably more.
A newly born blue whale is 7m long and weighs 2,500 kg. It drinks 400 - 500 litres of milk a day and gains about 100 kg of body weight each day. Blue whale calves remain with their mothers for six months; when weaned they are 14- 15 m long and weigh around 20 tonnes. Female blue whales give birth to a single calf once ever two or three years after a pregnancy of about a year.
A blue whales eat mostly krill (tiny shrimp like creatures) and feeds by lunging at speed into a krill swarm, engulfing both krill and water, taking tens of tons of water into its mouth. A pleated pouch on the underside of the mouth expands to let the water in, a curtain of baleen plates, which hang from the upper jaw, blocks the exit of the krill and then the pouch and tongue push the water out. Once the whale's head is above the water,it can swallow the krill. An Antarctic blue whale can eat up to 3,500 kg of krill a day but they eat only in the feeding season. For the rest of the year they do not eat at all.
Blue whales are fast swimmers, able to reach 50 kph over short distances. This, and their great strength, protected them from whalers for many centuries - a blue whale struck with a hand harpoon would run out all the line in a whaling boat and would tow the boat under if the line were not cut quickly. But the invention of the harpoon cannon changed that and blue whales became prime targets because of their large size. In the Antarctic 99.5% of the population was caught and it is not known if it will ever recover. Catches of blue whales off the coast of Japan peaked in 1911, with a catch of 243 and fell to 7 a year by 1964 when catching was ended.
A newly born blue whale is 7m long and weighs 2,500 kg. It drinks 400 - 500 litres of milk a day and gains about 100 kg of body weight each day. Blue whale calves remain with their mothers for six months; when weaned they are 14- 15 m long and weigh around 20 tonnes. Female blue whales give birth to a single calf once ever two or three years after a pregnancy of about a year.
A blue whales eat mostly krill (tiny shrimp like creatures) and feeds by lunging at speed into a krill swarm, engulfing both krill and water, taking tens of tons of water into its mouth. A pleated pouch on the underside of the mouth expands to let the water in, a curtain of baleen plates, which hang from the upper jaw, blocks the exit of the krill and then the pouch and tongue push the water out. Once the whale's head is above the water,it can swallow the krill. An Antarctic blue whale can eat up to 3,500 kg of krill a day but they eat only in the feeding season. For the rest of the year they do not eat at all.
Blue whales are fast swimmers, able to reach 50 kph over short distances. This, and their great strength, protected them from whalers for many centuries - a blue whale struck with a hand harpoon would run out all the line in a whaling boat and would tow the boat under if the line were not cut quickly. But the invention of the harpoon cannon changed that and blue whales became prime targets because of their large size. In the Antarctic 99.5% of the population was caught and it is not known if it will ever recover. Catches of blue whales off the coast of Japan peaked in 1911, with a catch of 243 and fell to 7 a year by 1964 when catching was ended.
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