The Blue Whale

THE BLUE WHALE.
The Blue whale is a marine mammal belonging to the suborder of baleen whales. Blue Whales can reach up to 33 metres in length and 180 metric tons or more in weight. In volume, it iscurrently the largest animal existing known to have existed.
Long and slender, the blue whale's body can be various shades of bluish-grey dorsally and somewhat lighter underneath. There are at leastthree distinct subspecies: B. m. musculus of the North Atlantic and North Pacific, B. m. intermedia of the Southern Ocean and B. m. brevicauda found in the Indian Ocean and South Pacific Ocean. B. m.indica, found in the Indian Ocean, may be another subspecies. As with other baleen whales, its diet consists almost exclusively of small crustaceans known as krill.
Blue whales were abundant innearly all the oceans until the beginning of the twentieth century. For over 40 years, they were hunted almost to extinction by whalers until protected by the international community in 1966. A 2002 reportestimated there were 5,000 to 12,000 blue whales worldwide, located in at least five groups. More recent research into the Pygmy subspecies suggests this may be an underestimate. Before whaling, thelargest population was in the Antarctic, numbering approximately 239,000. There remain only much smaller concentrations in each of the North-East Pacific, Antarctic, and Indian Ocean groups. There aretwo more groups in the North Atlantic, and at least two in the Southern Hemisphere
Mating starts in late autumn and continues to the end of winter. Little is known about mating behaviour or breedinggrounds. Females typically give birth once every two to three years at the start of the winter after a gestation period of ten to twelve months. The calf weighs about 2.5 metric tons and is around7 metres in length. Blue whale calves drink 380–570 litres of milk a day. Weaning takes place for about six months, by which time the calf has doubled in length. Sexual maturity is typically reached...