Blue Whale Fact File

Balaenoptera musculus








Wild 90 years

Record 110 years




Conservation Status



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.


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.


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.

Blue Whale


Blue whales can be found in all oceans across the globe.


These animals are found in aquatic areas. Each population appears to undertake some form of migratory behavior with their summering and wintering areas being occupied year round.

They mostly live in deep water and rarely seen near shore.

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Females give birth during winter. They will migrate prior to this to warmer waters at lower latitudes.

Here they give birth to a single calf after a gestation period of 12 months. At birth the calf is already massive measuring 7m (23ft) long with a weight of 2.5tonnes (2.7tons).

This calf will suckle milk from the mother for 6-8 months.

The youngest record age for a female to calve was 11 years old. A female will give birth once every two to three years.


Outside of the breeding season the blue whale is solitary. Where food is abundant they may gather in small groups to feed.

Blue whales produce the loudest sounds of any animal reaching 180 decibels. The vocalizations produced include grunts, hums and moans. A low frequency whistle is used to attract with other blue whales.

These animals can dive to depths of up to 200m (655ft). They are propelled down by swishing the rear body and fluking the tail up and down. While swimming their average speed is 8km/h (5mph).

Blue whales push water 9-12m (30-40ft) in the air when they push air out through their two blowholes.

Blue Whale

Predators and Threats

Threats to the survival of the blue whale include vehicle strikes. They are also subject to some incidental catches by fishing ships but their large size means this rare.

An emerging threat to the species is the decline of their food source due to ocean warming caused by climate change.

Humans are affecting them through habitat degradation and pollution. They can also become entangled in fishing lines.

Previously the largest threat to the blue whale was hunting to supply the whale trade. This was reduced after they received legal protection globally in 1966 and the last recorded purposeful catch was in 1978.

At present the mature population is believed to include 5,000-15,000 individuals. It is believed that the population is increasing in size but it is still a significant reduction on the estimated 140,000 individuals which were part of the population in 1926.

Quick facts

Blue whales are the largest animals on Earth and produce the loudest sounds of any animal on Earth.

Blue Whale

Photo Credits


Public Domain


Burnie, D., 2011. Animal. 3rd ed. London: DK

Ambrose, J., 2015. Wildlife Of The World. 1st ed. London: Dorling Kindersley

Jackson, T. and Chinery, M., 2012. The illustrated encyclopedia of animals of the world. London: Southwater.

World Wildlife Fund. 2021. Blue Whale | Species | WWF. [online] Available at: <> [Accessed 31 July 2021].

Cooke, J.G. 2018. Balaenoptera musculus (errata version published in 2019). The IUCN Red List of Threatened Species 2018: e.T2477A156923585. Downloaded on 31 July 2021.

Oceana. 2021. Blue Whale. [online] Available at: <> [Accessed 1 August 2021]. 2021. Blue whale. [online] Available at: <> [Accessed 1 August 2021].

NOAA. 2021. Blue Whale. [online] Available at: <> [Accessed 1 August 2021].

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