A video demonstrating the true size of blue whales through size comparisons. Credit: Facts in Motion.

Blue whale (Balaenoptera musculus), commonly known as sulfur-bottom whale, is the largest mammal ever known to have lived on Earth, according to Guinness World Records. Some specimens weigh as much as 200 tonnes, although the average is 100–150 tonnes. Found in all the world’s oceans, the blue whale travels thousands of kilometers 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.

The following is the biology of blue whales that has set world records:

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, it is the heaviest tongue of any animal
3. The brain is proportionately tiny. It tips the scales at around 6 kg; for context, human brains weigh about 1.4 kg
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
5. The largest heart of any living creature weighs in at around 680 kg – 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 wide – nearly as long as a London double-decker bus
7. The blue whale is as long as 1 Boeing 737, 3 double-decker buses, 5 African elephants, 11 smart cars, or 17 humans
8. The blue whale is as heavy as  4 Boeing 737s, 15 double-decker buses, 40 African elephants, 270 smart cars, or 3,333 humans

This article originally appeared in Guinness World Records of February 18, 2022.