Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff,
Speaker 1: I'm Lauren folk Bomb, and you and I can complain
Speaker 1: about seasonal chills all we want, but at the end
Speaker 1: of the day, we're basically walking furnaces. Humans are endotherms,
Speaker 1: meaning that our bodies produce heat internally. We're also able
Speaker 1: to maintain a body temperature that stays more or less constant,
Speaker 1: so we should count our blessings. Not all animals have
Speaker 1: these physiological advantages. Apart from a handful of species like
Speaker 1: the monstrously big leather back sea turtle, very few reptiles
Speaker 1: or amphibians are able to keep their bodies at a
Speaker 1: constant temperature, and since they can't warm themselves up, these
Speaker 1: creatures must extract heat from their environment. But what happens
Speaker 1: when that environment gets colder? How to frogs, snakes, and
Speaker 1: turtles make it through the winter months in places that
Speaker 1: see blankets of snow, iced over lakes and subfreezing temperatures
Speaker 1: year after year. A lot of reptiles and amphibians undergo
Speaker 1: periods of extreme seasonal inactivity. When the weather gets colder.
Speaker 1: They may experience decreased heart rates, slowed metabolisms, and lower
Speaker 1: overall body temperatures. Scientists disagree over what to call this state.
Speaker 1: Everyone accepts that it's some kind of dormancy, but while
Speaker 1: some experts classify it as hibernation, others referred to it
Speaker 1: as brumation. Dormant snakes generally hold themselves up in winter dens.
Speaker 1: These shelters may take the form of an abandoned rodent burrow,
Speaker 1: an exposed crevice on a rock face, or some naturally
Speaker 1: occurring hole underneath a tree. Various snakes have also been
Speaker 1: known to turnhousehold basements or garages into winter lodges in
Speaker 1: seasonally cold areas like Canada and the northern United States.
Speaker 1: Snakes must choose their dens with care. Ideally, a winter
Speaker 1: hangout spot will descend below the local frost line, the
Speaker 1: maximum depth beneath the ground at which soil freezes. Hiding
Speaker 1: out underground is the survival strategy of choice for lots
Speaker 1: of tortoises and turtles as well. Some species, such as
Speaker 1: the gopher tortoise, dig their own burrows, but it's not
Speaker 1: uncommon to find the shelled reptiles occupying pre dug unoccupied
Speaker 1: rodent holes. Now, a hibernating lack bear can sleep for
Speaker 1: more than one hundred days straight without consuming any food
Speaker 1: or water. Reptiles tend to be more active during hybernation
Speaker 1: or romation. When a midwinter warm spell comes along, they'll
Speaker 1: use it as an opportunity to crawl up to the surface,
Speaker 1: bask in the sunlight for a little while, and maybe
Speaker 1: grab a quick drink. Reptiles are perceived as loaners, a
Speaker 1: reputation that isn't entirely deserved. Consider the Eastern diamond back rattler,
Speaker 1: who doesn't seem to mind collaborating with gopher tortoises. Members
Speaker 1: of both species will sometimes go dormant together inside the
Speaker 1: same burrow. Likewise, snakes often share their dens with other snakes.
Speaker 1: Garter snakes are famous for hibernating in huge groups that
Speaker 1: may consist of hundreds or even thousands of individuals. One
Speaker 1: Canadian den reportedly contained no fewer than eight thousand snakes.
Speaker 1: Indiana Jones and other videophiles will want to keep their
Speaker 1: distance as snakes go. Garters are remarkably cold tolerant. One
Speaker 1: species can even survive the unbelievable experience of having of
Speaker 1: the liquid water inside its body freeze solid, but only
Speaker 1: if it's allowed to thaw out after a few hours,
Speaker 1: but the wood frog takes freeze tolerance to a whole
Speaker 1: new level. A North American native, this cold weather warrior
Speaker 1: has the distinction of being the only amphibian in the
Speaker 1: Western hemisphere whose range extends into the Arctic Circle. Every autumn,
Speaker 1: wood frogs bury themselves under a thin blanket of leaf
Speaker 1: litter on the forest floor. There they will remain dormant
Speaker 1: for up to eight months. In the process, the heart
Speaker 1: temporarily stops beating and the frogs enter a state of
Speaker 1: suspended animation. Left to the mercy of the elements, the
Speaker 1: amphibians freeze at temperate and polar latitudes. Fortunately, the liver
Speaker 1: pumps loads of glucose into the bloodstream, while urine is
Speaker 1: retained within the body. All that helps keep the cells
Speaker 1: from drying out, which is what would normally happen during
Speaker 1: the freezing process. Therefore, a full six of all the
Speaker 1: water in a wood frog's body can become frozen, and
Speaker 1: the amphibian will still live to rib it another day. Moreover,
Speaker 1: the frog may be kept frozen at negative eighteen degrees
Speaker 1: celsius or about zero degrees fahrenheit, for as long as
Speaker 1: two hundred and eighteen days. Another example of this cool
Speaker 1: survival strategy can be found in far North Russia. The
Speaker 1: Siberian salamander lives in areas that get temperatures of negative
Speaker 1: fifty degrees celsius that's negative fifty eight fahrenheit or lower.
Speaker 1: To stay alive, it hibernates underneath logs, vegetation, and snow banks.
Speaker 1: A compound in their bloodstream keeps the critters alive when
Speaker 1: the majority of its body water turns to ice. Terrestrial
Speaker 1: amphibians with poor digging skills, like the wood frog, tend
Speaker 1: to either hibernate in pre existing burrows or fine shelter
Speaker 1: at ground level. Good burrowers, such as the American toad
Speaker 1: and spotted salamander, proactively dig winter holes from themselves that
Speaker 1: extend below the frost line. For aquatically inclined amphibians, there's
Speaker 1: another option. Bullfrogs are lake and pond denizens who find
Speaker 1: oxygen rich bodies of water and spend their winters imprisoned
Speaker 1: under the surface of ice that forms there. Painted turtles
Speaker 1: employ a similar strategy. Reptiles generally use their lungs to breathe,
Speaker 1: but some semi aquatic turtles can also absorb waterborne oxygen
Speaker 1: through their skin over wintering. Painted turtles do this extremely well,
Speaker 1: Plus they can lower their metabolic rates to the tune
Speaker 1: of each winter. That's how they stay alive with the
Speaker 1: thick sheets of lake ice for months on end. Sometimes
Speaker 1: you can even see them swimming around under the frozen barriers.
Speaker 1: But why go through the hassle of skin breathing when
Speaker 1: you can turn your snout into a snarkle. In January,
Speaker 1: the Internet was greatly amused by some North Carolina alligators
Speaker 1: whose noses were seen poking up out of a frozen pond.
Speaker 1: Gators can't survive being trapped in icy water for much
Speaker 1: longer than a week or so. For long term winter lodgings,
Speaker 1: they construct deep burrows out of waterside mud. Today's episode
Speaker 1: was written by Mark Nancini and produced by Tyler Clang.
Speaker 1: For more on this and lots of other warm topics,
Speaker 1: visit our home planet, how Stuff Works dot com