Blue Whale

Known as the largest mammal on earth, blue whale is an enormous animal of the genus Balaenoptera and the family, Balaenopteridae. Its scientific name is Balaenoptera musculus. This large marine mammal of the suborder, baleen whales is not only the largest mammal on earth, but possibly the largest animal to have ever existed on earth. Despite their physical resemblance to fish, Balaenoptera musculus are mammals with the distinct mammalian characteristic. As for example, they are warm blooded, give birth to young ones and nurse them, breathe air into the lungs and have some hair as well. Given below are some more blue whale facts, regarding its physical appearance, size, habitat, diet and reproduction.

Blue Whale Information

Physical Appearance
Blue whales are known to possess a long and slender body, which is somewhat tapered. The dorsal side of the body is usually bluish green in color, while the ventral side is lighter. The skin of these whales is mottled or spotted. But underwater, their skin looks luminous aqua blue in color. But, when they reach the waters of Antarctic and North Pacific oceans, their underside looks somewhat yellowish green in color, rather than bluish green. This change in color is due to the fact that diatoms grow on their underside of the body when they reach these oceans. Whales possess nostrils, which are known as 'blowholes'. Blue whales generally have two blowholes, which are located at the top of the head, and are contained in a large and raised 'splash guard'.

Their head is flat and almost U shaped, with a ridge that extends from the blowholes to the upper lip or the snout. The head of these large mammals accounts for about one-fourth of the total length of the body. The mouth is thick due to the presence of baleen plates, that helps to filter out the foods. These whales also contain several ventral pleats that run along the throat. These pleats enable the whales to expand their throat, so that they can gulp down a large amount of food containing water. Other distinguishing features of this animal are, presence of small, falcate dorsal fins (can be found near the flukes), short and tapering flippers and broad and triangular fluke. A thick layer of fat, known as blubber is present just beneath the skin, which helps to insulate or keep them warm in the cold water of the ocean.

Size of Blue Whale
Due to their enormous size, blue whales are very difficult to weigh and measure. Till now, the longest blue whales ever recorded were two females of 109 to 110 feet. It has been estimated that a 98 feet whale can weigh more than 180 tons or 200 short tons. It has been observed that blue whales of the Southern hemisphere can reach a length of 90 to 100 feet. On the other hand, those found in Northern hemisphere are generally observed to be smaller than their Southern hemisphere counterparts. The whales of Northern hemisphere usually grow up to a length of 75 to 80 feet. The females are generally larger than the males.

Blue whale Habitat
Previously, i.e. before the large-scale commercial whaling occurred in the twentieth century, blue whales were to be seen in nearly all oceans. Presently, the main blue whale habitat is the cold and temperate waters of the Arctic and Antarctic oceans. They generally prefer the deeper ocean water, rather than the coastal water. During winter, they are known to migrate from polar waters to temperate waters, in order to mate and give birth to the young ones.

Blue Whale Diet
The main food of these gigantic whales are tiny krill, which are shrimp like creatures. They also eat planktons and small fish. It is estimated that a blue whale on an average consumes approximately 40 million krill a day, during the summer days. The pleats found along its throat enables it to expand the throat to gulp down a large amount of water along with the foods. When it closes the mouth, water is expelled from the body through the comb like plates, known as baleen plates, while the food is retained near the tongue.

Reproduction
Blue whales usually reach the age of sexual maturity between 6 to 10 years. By this time, the male reaches a length of 74 feet, while the female grows up to a length of about 79 feet. The female gives birth to a calf every 2 to 3 years. The gestation period is 10 to 12 months. At the time of birth, a calf is usually 23 to 27 feet in length and weighs about 3 tons. The female nurses the calf for about 7 to 8 months and during this period, a young blue whale can drink 380 to 570 liters of milk.

Behavior
Blue whales can be spotted alone or in small groups. However, more commonly they are found in pairs. During winter, they migrate to temperate waters. They can emit low frequency, but very loud sounds. The sounds produced by these whales can be louder than the sound of a jet engine. Why they make these sounds is not very clear. But, scientists are of the opinion that, these sounds could be used for communicating with other whales to maintain inter-individual distance, to attract and find mates, as well as to locate the prey.

So, this was some interesting information about blue whale. One of the greatest threats to the existence of these amazing animals is whale hunting. In fact, their population got reduced significantly during the beginning of the 20th century due to large-scale whaling or whale hunting. In 1966, hunting of blue whale was banned by the International Whaling Commission. Subsequently, conservative efforts were taken to protect these mammals and these efforts are expected to increase their numbers gradually.