Why can some animals hold their breath for a really long time? I.e., turtles, dolphins, whales, etc… Do they have really big lungs for their size? Do they store oxygen in places other than their lungs? Do they have lower oxygen needs than humans? Are they just more efficient at using oxygen?

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Why can some animals hold their breath for a really long time? I.e., turtles, dolphins, whales, etc… Do they have really big lungs for their size? Do they store oxygen in places other than their lungs? Do they have lower oxygen needs than humans? Are they just more efficient at using oxygen?

In: 8

Yes to all (depending on the animal in question):

– They have of course large lungs (size vs weight vs volume).
– They can store oxygen in blood (more red blood cells for more oxygen binding), lungs and muscles (up to 30x more in muscles for example compared to land based animals).
– They can use anaerob energy generation (non-oxygen energy generation) and their body supports that better than in other animals (muscle acid).
– They can slow down their metabolism, especially for resting.
– The larger the animal the slower is the metabolism compared to the size.
– More efficient propulsion system (so more oxygen remain to stay underwater instead of being wasted to travel).

SYL

All of the above!

Specifically for dolphins and whales as that’s my area of expertise but similar adaptations can be found in other marine mammals:

– large lung volume allows for one big breath filled with as much oxygen as possible

– modified lung surfactant (substance that costs the inside of the lungs) allows for almost complete collapse of the lungs when at depth. This helps force the gas inside the lungs to be absorbed into the blood, making it available for the body

– flexible ribs help with lung collapse

– more oxygen-binging molecules in blood but more importantly in muscles. You know how chicken meat is rather pale compared to beef? Dolphin nest is several shades darker still, almost dark brown. This is due to more myoglobin, a molecule that binds oxygen in the muscles. This means that once oxygen is stored in the muscle, no transport from the lungs is required, therefore no breath, allowing for deeper and longer dives until the myoglobin stocks run out

– selective shunting of the blood away from irrelevant organs. While on a deep dive, it’s unnecessary for the dolphin to waste energy on digesting food for example, it’s better to use it for hunting or swimming. Therefore blood flow to the stomach is limited, allowing for the precious oxygen and nutrients to be available for the muscles.

– higher breath exchange volume. When we humans breathe through one cycle (inhale-exhale), we only exchange about 10-15% of the air in our lungs. That’s fine for us as we live in an environment where there is plenty of air. Dolphins can exchange as much as 95% of their lung volume which means they don’t have to spend much time at the surface before they are ready for the next five, and can recover from a dive much faster than we do

In addition “cold-blooded” or ectomorphs don’t be expend energy maintaining their body temperature and so they may go for much longer periods without taking a breath.