Eli5: Why do small animals like squirrels not lose appendages to frostbite when temperatures reach below freezing, and they walk around on ice and snow all day?

Question

Eli5: Why do small animals like squirrels not lose appendages to frostbite when temperatures reach below freezing, and they walk around on ice and snow all day?

In: Biology

Answer 1

Countercurrent heat exchange **does not** prevent frostbite, if anything it reduces peripheral limb temperature as well as promote vasoconstriction. It does however preserve core body heat, reducing the risk of hypothermia.

PS it’s the same stuff that keeps yer balls cool.

[https://en.wikipedia.org/wiki/Countercurrent_exchange#Countercurrent_exchange_of_heat_in_organisms](https://en.wikipedia.org/wiki/Countercurrent_exchange#Countercurrent_exchange_of_heat_in_organisms)