Blue Whale

Blue whales form close ties with one another and are often seen in groups of two or four. Mating takes place in the warm waters of the tropics, where the young are born. The mother gives birth to a single calf with the aid of other females, who help her deliver the calf and then nudge the newborn to the surface for its first breath of air. At birth, the calf measures about 23 feet and weighs 16000 pounds. The baby suckled in the water, drinking more than 160 gallons of milk a day. At 7 months, it is able to catch its own food.

In the Antarctic, blue whales feed on vast quantities of a plankton called krill. In Arctic waters, they feed on only three species of crustacean (shelled) plankton. Icy water contains more oxygen and carbon dioxide than warm water, which makes it rich in marine life. Plankton is up to twenty times more abundant in the Arctic and Antarctic than it is in the warm waters of the tropics. In spite of its bulk, the blue whale can reach speeds of 10-15 knots. But it catches most of its food by diving. It can dive to depths of 1650 feet and lie submerged for up to 2 hours. Rising from the depths, the whale feeds by collecting a large amount of seawater in its mouth and then straining out the plankton.

Because of its great size, the blue whale was a prime target for the whaling industry. Its body was a source of oil and the baleen was used to make women's corsets. Antarctic whalers slaughtered 30000 blue whales from 1930 to 1931. The population has since recovered, but there are probably less than 10000 alive today; they are now protected.