Whale is the biggest species that is still surviving in water bodies mainly in oceans. It was originally found 50 million years ago in Eocene epoch. Early whales lived on land, but they moved into water due to rich food supply which are now fully-developed marine mammals. 

This species is considerably popular because it is the biggest and the heaviest creature in the world. The size of a typical blue whale is around 100 feet that can reach 110 feet and they weigh up to 200 tons. Its tongue alone weighs as much as an elephant and heart as much as an automobile. 

They look totally blue underwater, whereas they seem blend of blue and grey while being on the surface. Unlimited microorganisms inhabit in their skin that reflects yellowish hue on their bellies. It has a long, wide and flat head and a long body which further ends with triangular flukes. Scientific study has shown that each blue whale has a unique marking. 

Blue whale are noticed swimming alone or in pairs for most of the time, but they hardly like being a part of a small team. Although human is unable to hear them, they are probably the loudest animals on earth. They spend most of their time by sleeping, making friends, socialising, exploring and moving to different areas.

Their dietary intake includes krills that resemble shrimps, but sometimes they consume small fish unintentionally.

The way they swim is most of as an aeroplane flies. They move in water by flexing their tails upward and downward. They change direction using the side flippers. They also acquire dorsal fins which help them stabilising their whole body while swimming. They swim very fast. They generally cover 5 miles an hour that they can maximize up to 20 miles per hour.

It is estimated that blue whales' lifespan is 80 to 90 years in open sea. They are too large to breed in captivity.  

They live in oceans excluding Arctic. They actually like warmth, so they migrate to other regions to keep their body warm in the winter season. Sometimes they move along the coasts in cold temperatures. 

According to previous records, any blue whale hasn't attacked on any human being in the wild, but in the captivity, they are harmful to humans and caused some deaths. Divers usually swim along with them and they haven't reported any injury caused by blue whales