Blue whales are the largest animals ever known to have lived on Earth. Its body is very long, tapered and streamlined and can grow up to 100 feet (30 meters) long and upwards of 200 tons (181 metric tons). The head is broad, long and almost U-shaped, accounting for up to a quarter of the animal’s total length. Their tongues alone can weigh as much as an elephant and their hearts, as much as an automobile. Blue whales diet mainly consists of euphasiids (krill) and mysids.
The Blue whale is blue-grey in color, often with lighter grey mottling on a relatively dark background (or the reverse). The underside is paler, sometimes white, though microorganisms growing on the skin sometimes cause it to take on a yellowish-green tint.
Blue whales are fast and a strong swimmer, cruising at about 20 km/h and capable of reaching speeds of 45 km/h when agitated.
Blue whales live in all the world’s oceans occasionally swimming in small groups but usually alone or in pairs. They often spend summers feeding in polar waters and undertake lengthy migrations towards the Equator as winter arrives.