The blue whale is the largest animal to have ever lived on earth with females reaching lengths of up to 30m (98ft) long with a weight of 160 tonnes (157.5 tons).

They are found in the world's oceans. They are migratory and will move between the feeding grounds in summer and a breeding site in winter.

These animals feed almost exclusively on tiny crustaceans known as krill. To power such a large animal they require up to 6 tonnes or 13,000lbs of food each day. When feeding they take in large amounts of water and then filter out the food.

Blue whales were almost hunted to extinction until whaling was banned in 1966. They still face threats including habitat destruction, pollution and boat strikes.

Learn more about these magnificent mammals by reading on below.

Appearance

As their name suggests the body of the blue whale is colored blue-grey across its body. This is patterned with variable mottling which is pale grey or white. On the underside of the body in the front half they have a white patch.

Running along half the body are 55-68 skin grooves which may also be known as pleats.

The blue whale represents the largest animal found on Earth today. For perspective their weight is equal to 33 elephants and their heart is the size of a Volkswagen beetle car. Their blood vessels carry 10 tonnes of blood and are large enough for you to swim through.

Their body shape is incredibly hydrodynamic which allows them to easily move through the water. On top of the body is an incredibly small fin. The large tail at the back of the body is used to propel them through the water.

An average blue whale will reach lengths of 20-30m (66-98ft) long with a weight averaging 100-160tonnes (98.5-157.5tons). Females tend to be slightly larger than males.

The large size of the blue whale is possible due to the buoyancy provided by sea water. A similarly size animal living on land would be crushed under its own weight.

Diet

Blue whales are carnivores which feed almost entirely on krill. These are tiny floating crustaceans.

To power their massive body these whales must eat up to 6 tonnes or 13,000lbs of food each day. So that they can take in these large volumes of food they will distend the pleated throat out to four times its size.

They will take in large mouthfuls of water which contain high numbers of the food. The water is then expelled and the food swallowed.

While migrating they may eat very little food and have been able to survive for up to 4 months on their blubber reserves.