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The record-setting anatomy of the blue whale: a look inside the largest animal in the world

By Rob Dimery
Published

The blue whale is the largest animal, with some specimens weighing in at a colossal 200 tonnes (440,000 lb), although 100–150 tonnes (200,000–300,000 lb) is the average. 

Even dinosaurs didn’t reach that size – for instance, it’s nearly 20 times heavier than a T. rex! 

The blue whale can grow up to 30 m (98 ft) long – around the same as a Boeing 737. 


Found in all the world’s oceans, the blue whale travels thousands of miles every year, breeding in the tropics during the winter and swimming to more extreme latitudes to feed in summer. This also makes this species the largest migrant in the animal kingdom.

Watch and read about more record-breaking animals on our animal showcase pages

Perhaps surprisingly, this behemoth of the deep feeds mainly on some of the ocean’s smallest inhabitants: tiny crustaceans called krill that reach no longer than a few centimetres. 

It swallows them in great gulps of seawater before raising its tongue to its mouth, straining the briny liquid through baleen plates but retaining its prey. This unparalleled difference in size between predator and prey represents yet another natural record.

Intensive whaling in the early 20th century devastated the world’s blue whale populations. But thankfully, since being designated a protected species in 1966 its numbers have started to rise again. 

With our continuing support, blue whales will be around for future generations to marvel at for many years to come.

Record-breaking blue whale biology

  1. Each upper jaw features about 400 plates of bristle-like keratin called baleen, which traps the krill that the whale feeds on
  2. Weighing in at 4 tonnes (8,800 lb), it is the heaviest tongue of any animal
  3. The brain is proportionately tiny. It tips the scales at around 6 kg (15 lb); for context, human brains weigh about 1.4 kg (3 lb)
  4. That huge body demands a lot of oxygen, so little wonder that they also boast the largest lungs, with a capacity of 5,000 litres (1,320 US gal)
  5. The largest heart of any living creature weighs in at around 680 kg (1,500 lb) – about the size of a VW Beetle car! It beats just four to eight times a minute – the slowest heart rate for a mammal
  6. The tail flukes are 7.6 m (25 ft) wide – nearly as long as a London double-decker bus

How big is the blue whale?

The blue whale is as long as...

The blue whale is as heavy as...