The blood of the North American wood frog helps it survive freezing temperatures for as long as seven months via a natural antifreeze.

References

"The North American wood frog (Rana sylvatica), for instance, can survive freezing temperatures for as long as seven months, relying on a natural antifreeze in its blood to protect its organs." (Morell 2001)

Journal article
The fragile world of frogsVirginia Morell

Living System/s