The blue whale is a marine mammal and is the largest animal known to have ever existed. It has been measured up to 98 ft in length and with a maximum recorded weight of 173 tonnes (190 short tons).
The blue whale's long and slender body can be various shades of bluish-grey dorsally and somewhat lighter underneath. It has a long tapering body that appears stretched in comparison with the stockier build of other whales. The head is flat, U-shaped and has a prominent ridge running from the blowhole to the top of the upper lip.
A blue whale's tongue weighs around 2.7 tonnes (3.0 short tons) and, when fully expanded, its mouth is large enough to hold up to 90 tonnes (99 short tons) of food and water.