How do animals maintain their body heat? Why don’t animals get frost bite? How can the same animal do fine living in 90 degree heat and 3 months later do fine when it might be 10 below zero all night long? Obviously a naked mole rat cannot live outdoors in Yellowstone National Park year round but I want to know what mechanism all the animals that do are using or have. Thanks.
Animals can, and do, get frost bite, but it takes a bit more exposure to cold in order to do it since their fur/hair acts as an insulation. In general, though, animals control body heat the same way humans do; insulating coats (of fur rather than GoreTex), sweating to cool down, shivering to raise temperature at the expense of energy, and adaptive circulation (bringing blood flow away from extremeties in the cold in order to keep the core warm, and bringing blood to the surface in warmth to enhance convective heat transfer with the air). Keeping warm means doing some sort of work to provide heat, and that’s usually done by moving and chemical reactions on the food the animal consumes. Many animals have coats that thicken for the winter months to provide added insulation, and go through a significant shedding period before the start of the summer to avoid over heating. This allows them to adapt to wide temperature ranges, but as I said, animals can get frostbite and hypothermia, and can also overheat.
animals in cold climates do like fur coats. they do grow and shed insulating hair as needed.
What sort of other mammals sweat? Do all mammals sweat except dogs?
(I’m not trying to call you out, I am trying to learn!)
Horses and non-human primates sweat. Dogs actually do have sweat glands, but it’s a very small number. Primarily they cool themselves by panting.
Another piece of trivia I recall - pigs don’t sweat, which is why they like to roll in mud and whatever else is moist, to cool off.
Nobody’s mentioned reptiles yet, where the answer is “they don’t” (for the most part). Reptiles can still die if the weather is extremely cold or extremely hot, but their biology/biochemistry is just not as temperature sensitive as mammals. A snake can have an internal temperature of 50 F and do just fine, whereas a human would be dead.
Yaks have a very cool mechanism for keeping their feet from freezing. The tissues of the feet do just fine at low temperatures, and the blood vessels in the legs have arteries and veins intertwined. This means that hot blood coming down to the legs transfers heat into cold blood returning from the feet. The feet stay cool and the yak loses less total body heat through the feet.
All animals have that countercurrent exchange mechanism, including humans. Which is why your fingers can be noticeably cold to the touch while you core temperature remains above 370C.
The mechanism is better developed in some animals, and most well developed in the sea birds, which is why they can stand on ice or swim in water well below freezing without suffering any ill effects.
Nitpick: 370 K. A temperature of 370C would be 698F, and not only dead and cooked but largely burnt.
37oC , not 370C.
Even 370 K is nearly boiling.
The other aspect of this is that humans are a lot more capable of taking cold than most people realize. As long as it’s dry out and you stay active, you can survive unprotected at sub-freezing temperatures. You’ll be really uncomfortable, but you’ll survive. Well, wild animals in winter are uncomfortable, too, but they survive also.
Almost all mammals have sweat glands, the exceptions being aquatic mammals like whales. However, not that many use sweating as a primary method of heat regulation in the way that humans do. In many species the sweat glands are confined mostly to the soles of the feet.
Some information on the subject can be found in my Staff Report (with Doug):
What makes some animals cold-blooded and others warm-blooded?
I’ve often marveled at animals’ ability to keep warm myself. Mostly I think of birds’ legs and skinny deer legs. They’re mostly skin and bone. It just seems such an insurmountable task, keeping such thin and relatively unprotected limbs warm. Wouldn’t human fingers be frozen solid in similar conditions?
That’s the point, at least for birds. The lower limbs are mostly just tendon and bone, and there isn’t a lot of muscle or other tissue that needs to be kept from freezing. And they have a countercurrent system as mentioned above so that the extremities can be kept a a considerably lower temperature than the core.
Humans are capable of adjusting to comfort in a wide range of temperatures as long as we have full exposure to gradual changes. We have brown fat too, it just needs to be properly developed to serve it’s purpose - a simple solution for me has been cold showers, I used to be very cold-sensitive. We can only go so low in temps without clothing (in place of fur/feathers) of course.
Located chiefly under their paws which anyone that has seen the sweaty footprints of a dog on a hot summer’s day can attest. The same goes for cats, I assume.
Yep, they sure do - they also sweat nervously - as in, at a vet visit - and leave little sweaty kitteh pawprints on the exam table sometimes.