The Blue Whale

The blue whale is a marine mammal belongs to the suborder of baleen whales. It can grow up to 33 metres in length and 180 metric tons or more in weight; it is the largest mammals know to have existed in the ocean.
The blue whale body, long and slender can be various shades of bluish-grey dorsally and somewhat lighter underneath. Blue whale was abundant in nearly all the oceans until the beginning of the twentieth century. For over 40 years, the blue whales have been hunted almost to extinction by whale hunter until they are protected by the international community in 1966. Some report on the 2002 estimated that there were 5, 000 to 12, 000 blue whale in worldwide. It can be located in at least five groups. Blue whales are from a family that includes the humpback whale, the fin whale, Bryde’s whale, the sei whale and the minke whale. The family Balaenopteridae is believed to have diverged from the other families of the suborder Mysticeti as long ago as the middle Oligocene. However, it is known when the members of those families diverged from each other.
The blue whale has a long tapering body that appears stretched in comparison with the stockier build of the other whale. The head is flat and U-shaped and has a prominent ridge running from the blowhole to the top of the upper flip. The front part of the mouth is thick with baleen plates which are around 300 plates handing from the upper jaw, running 0.5m back into the mouth. Between 60 and 90 grooves run along the throat parallel to the body length. These pleats assist with evacuating water from the mouth after lunge feeding.
Blue whales can reach speeds of 50 kilometres per hour over short bursts, usually when interacting with other whales, but 20 kilometres per hour is a more typical travelling speed. When feeding, they slow down to 5 kilometres per hour. Blue whales most commonly live alone or with one other individual. It is not known how long travelling pairs stay together. In a location where a high concentration of food is, there will be as many as 50 blue whales will scattered over a small area. However, they do not form the large close-knit groups seen in other baleen species. Blue whale feed almost on krill, though they also take small numbers of copepods.