How can whales hold their breath for so long?

Rather than keeping oxygen in their lungs like humans do, whales' bodies are specially adapted to store oxygen in their blood and muscles. They have extraordinarily high levels of the oxygen-storing proteins haemoglobin and myoglobin.

Whales also reduce their heart rate and stop the blood flow to certain parts of the body, temporarily shutting down organs such as their kidneys and liver while they hunt. This helps them use the oxygen they have in their bodies more slowly.

Furthermore, beaked whales (which can dive for a particularly long time) have a streamlined body shape. Their flippers fit in indentations in the body, enabling them to take on a torpedo-like shape. This helps them to swim, and often to glide, with minimal effort and extend their oxygen stores for as long as possible.

Read the secrets of the deepest-diving whales.