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Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff,

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Speaker 1: Lauren Vogeldam, here you like most humans can probably hold

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Speaker 1: your breath for about two minutes, though in twenty sixteen,

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Speaker 1: Guinness World Records clocked free diver a leash Sigura Ventril

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Speaker 1: of Barcelona, Spain, holding his breath for a little over

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Speaker 1: twenty four minutes, which is of course completely wild. Humans

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Speaker 1: aren't built for breath holding. We've got other priorities like

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Speaker 1: world domination. If we had spent even a little more

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Speaker 1: of our evolutionary history working on holding in air instead

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Speaker 1: of making our brains giant and complex, we probably could

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Speaker 1: survive without oxygen at least as long as the average beaver,

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Speaker 1: which is fifteen minutes. But there are lots of air

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Speaker 1: breathing animals that are built for breath holding. A sloth

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Speaker 1: can hold its breath for a whopping forty minutes because

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Speaker 1: it's able to decrease its heart rate to about a

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Speaker 1: third of the normal. A sleeping sea turtle can hold

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Speaker 1: its breath for up to seven hours at a time.

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Speaker 1: A loggerhead turtles often forage under water for around forty

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Speaker 1: minutes in one go, but one study of loggerhead activity

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Speaker 1: found that males can voluntarily sustain themselves on one breath

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Speaker 1: or sometimes a quick charge up of several successive breaths,

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Speaker 1: for around ten hours. One female was observed going as

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Speaker 1: long as twenty hours. Some turtles can spend all winter

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Speaker 1: long at the bottom of a frozen lake in deep hibernation,

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Speaker 1: not using their lungs at all. The turtle secret is

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Speaker 1: that during this period of almost complete system shutdown, it

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Speaker 1: does take in a tiny bit of oxygen by breathing

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Speaker 1: through its highly vascularized cloaca. The cloaca being a single

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Speaker 1: organ found in reptiles, birds, amphibians, and even some mammals

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Speaker 1: that serves as the animals exit for its urinary tract

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Speaker 1: and digestive tract, and that's also the opening for their

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Speaker 1: reproductive tract. Yes, they pee, poop, and have sex with

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Speaker 1: this single organ in turtles with cloacal respiration, they can

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Speaker 1: also draw water up into their cloaca and absorb oxygen

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Speaker 1: from it, then flush it back out. Turtle, however, are

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Speaker 1: ectotherms animals that rely on outside sources for heat. It's

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Speaker 1: much easier for ectotherms to go without oxygen than endotherms

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Speaker 1: like us mammals. We use a lot of oxygen keeping

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Speaker 1: our systems running hot, which is why marine mammals like whales, seals,

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Speaker 1: and otters are so impressive. They can pull off unbelievably

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Speaker 1: long deep dives in order to hunt for food. Take

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Speaker 1: Couvies beaked whale the deepest diving of all marine mammals,

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Speaker 1: and the one scientists think holds the record for the

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Speaker 1: endotherm that's achieved the longest breath holding session. These midsized

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Speaker 1: whales can dive around ten thousand feet that's about three

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Speaker 1: thousand meters, hunting four squid and other deep sea goodies,

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Speaker 1: and they can hold their breath for an average of

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Speaker 1: sixty seven minutes, with one record dive that lasted a

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Speaker 1: hundred and thirty eight minutes before a Couvies beaked whale

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Speaker 1: broke the previous record. A northern elephant seal was the

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Speaker 1: gold medalist, caught holding its breath at a hundred and

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Speaker 1: nineteen minutes. A sperm whale now comes in third place

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Speaker 1: at ninety minutes. Not a long time to go without

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Speaker 1: oxygen when you've got an expansive mammalian metabolism to keep up,

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Speaker 1: but lots of marine and aquatic mammals make it work

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Speaker 1: by slowing their heart rates and redirecting blood away from

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Speaker 1: their extremities into their brains, hearts, and muscles. They even

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Speaker 1: have special oxygen binding proteins in their muscles that allow

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Speaker 1: them to store more oxygen than us land lovers. Today's

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Speaker 1: episode was written by Jessoline Shields and produced by Tyler

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Speaker 1: Clang for iHeart Media and How Stuff Works. For more

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Speaker 1: on this and lots of other multipurpose topics, visit our

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Speaker 1: home planet, how stuff Works dot com