See how long you can hold your breath - you'll probably last for around two minutes (the human average). The longest a human has ever managed to hold their breath is for just over 24 minutes! While this is seriously impressive for a human, it's nothing compared to other members of the animal kingdom, who can hold their breath for over three hours.
Holding our breaths might not have been top of the evolutionary priority list for humans, but it's a different story for other air-breathing creatures.
Turtles
Sea Turtles may have adapted unique features to live in the ocean, but they still require air to breathe. You could be forgiven for thinking these water-based creatures gain oxygen from their liquid environment as they can hold their breath for up to seven hours (depending on energy expenditure at the time).
Still, this extended breath-holding only occurs in cold waters during winter hibernation. The rest of the time, turtles generally swim to the surface every 4-5 minutes to catch their breath. And during normal activity levels, they don't hold their breath for any longer than 21 minutes.
Loggerhead turtles have even greater breath-holding power and regularly forage for 40 minutes before returning to the surface. And if held underwater (in a calm state), they can survive on one breath for as long as ten hours.
Turtles can hold their breath for such an impressive amount of time because they engage in cloacal respiration (breathing out of their butt to you and me). A key difference between turtles and us is that we are endotherms, and they are exotherms. This means we rely on a constant energy source to keep our bodies alive and functioning. In contrast, turtles adapt to the temperature of their environment.
If a turtle is in cold water, it leads to a slower metabolism and, therefore, lower energy and oxygen demands. In addition, turtles can uptake oxygen by moving water across blood-vessel-filled body surfaces. And their butts are particularly well vascularized, which means they can absorb oxygen well.
Cuvier's Beaked Whale
The longest recorded dive by a Cuvier's Beaked Whale lasted for 222 minutes, breaking a record for any diving mammal. It was also the deepest dive at more than 9,800 feet. Their lungs are particularly efficient at oxygen absorption, and particular adaptations allow them to hold their breath for extended periods.
The reason why animals such as whales can hold their breath for so long is that they still use oxygen during this time. This is thanks to the presence of oxygen-binding myoglobin, which have a positive bond, allowing more of them to bond in an animal's muscles without creating a clogging effect. And deep-diving mammals possess ten times more muscle myoglobin than we do, which is why they can hold their breath for much longer.
Sperm Whale
Sperm Whales can hold their breath for around 90 minutes without needing to come to the surface to breathe. This is because, like other whale species, a sperm whale's muscles and blood are adapted to hold higher oxygen levels.
In addition, whales can reduce heart rate and prevent blood flow to specific organs (temporarily shutting down things such as
the liver and kidneys). At the same time, they hunt to help extend their oxygen supply's longevity. This allows Sperm Whales to dive to depths of up to 2,000 meters thanks to their remarkable energy to store and conserve energy.
Many people ask how whales can sleep without drowning - the answer is that a whale's breathing is voluntary (compared to humans who breathe involuntarily). And these mammals engage in what is called “Unihemispheric sleep," whereby half of the brain sleeps while the other half stays alert. This way, a whale can ensure that its blowhole is always positioned to breathe oxygen from the ocean's surface.
Weddell Seal
Weddell Seals may not be able to hold their breath for as long as some of the other animals on this list, but they can still stay submerged for up to 80 minutes, which is pretty impressive. These long swims aim to forage and find new breathing holes.
The Weddell Seal lives in the icy waters of Antarctica and uses these impressive abilities to navigate a dangerous environment. Being able to dive to greater depths means they can look up to see the silhouettes of fish, which can nourish them thanks to an excellent sense of underwater vision. Even if it is dark, Weddell Seals can use their whiskers to find prey, thanks to their sensitivity to even the slightest movements.
One reason Weddell Seals can dive for such long periods is that they have a greater blood volume and increased amount of red blood cells compared to other mammals, which means they can carry more oxygen around at any given time.
Sloth
The last animal on this list may surprise you as it is a non-marine creature - the sloth! These slow-moving, land-based creatures can hold their breath for up to 40 minutes. You mightn't imagine that the sloth is skilled in water, but it can move three times faster in water than it can on land. These talented swimmers frequently hold their breath when submerged in water to evade predators.
Due to their slow-moving nature, the Sloth is in danger of being attacked by predators whenever it comes down from its habitat amongst the canopy layer of sense rainforests. For this reason, holding their breath is a vital skill that could save their life.
Sloths can hold their breath for so long because they can slow their heart rate by around a third, meaning that they use less energy and sustain themselves on lower amounts of oxygen. This means that they can generally hold their breath for even longer amounts of time than dolphins, which require greater amounts of oxygen for their high-energy lifestyles.
