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A great book about how animals survive super cold winters is "Winter World" by Bernd Heinrich.

Bernd is a super fascinating biologist who really dives deep in to things. At one point in the book I think he was talking about chipmunks surviving winter, and it goes really fun on the first principles. Something like: "chipmunks have a surface area of X m^2, and need to maintain an internal temperature of Y˚C. If the outside temperature is -40˚C they therefore they need to consume Z calories per hour just to maintain body temperature. Their favorite food are pine nuts from the white pine tree. The pine nuts each have B calories, so the chipmunk will need to eat D of them per hour. How many nuts can a chipmunk fit in its mouth? Well I found a dead one and shoved pine nuts in to its mouth until I couldn't fit anymore, and managed to get 17 in there. That means..."

1 year agoby durkie

> Nobody yet understands what starts the wood frog’s heart after being frozen and inert for the entire northern winter.

To me, that's the most fascinating part of the (already quite fascinating) story. Frog is frozen solid, there is no (to our knowledge) heartbeat or brain activity. It thaws and something happens that gets it going again.

I have trouble imagining what that mechanism could even look like. Tiny portion of brain responsible for keeping track of frozen-ness? Some chemical signaling from within the body cavity?

1 year agoby abound

Wood frogs only live 3-5 years, so they probably only go through a max of 5 of these cycles. I wonder how much cellular damage they accumulate during these cycles that they can tolerate due to short lifespans. They also have ~10,000x less neurons than a mammal.

Even if you had the biochemistry that was able to do this, how many cycles could a higher life form tolerate this, assuming it would even work? Complex life seems to sacrifice some resiliency, such as the ability to regrow limbs. Amphibians already seem to be particularly adept at regeneration.

1 year agoby dexwiz

Now I'm wondering all kinds of things about their brain. Are they capable of forming memories, and would they retain those memories after a freeze/thaw cycle?

Effectively they're dead when they freeze. I'm assuming there's no brain activity.. Which means when they thaw they're being restored to life. I wonder if any other animals experience this

1 year agoby pcthrowaway

Curious to how long the frozen structure can "survive". I wonder if it's a good idea to freeze one such frog and thaw it centuries later (an amphibian time-traveler!)

1 year agoby pkoird

Evolutionarily, amphibians are somewhat simpler than mammals, they're smaller than a lot of mammals and they don't live as long, so I suspect some of this is simply that "things that aren't there". They wouldn't have as many problems with advanced glycation end products because the temperature is so low. There's at least one other ice survival strategy: antifreeze proteins. The fir tree and a variety of arctic fish have these: https://pmc.ncbi.nlm.nih.gov/articles/PMC6691018/.

In all cases, I still don't understand how the membrane potentials are maintained or re-constructed in the thawing phase: any pointers?

1 year agoby killjoywashere

Aquatic turtles have another brumination (hibernation) strategy. Since they breathe air, yet may get trapped under the ice for months at at time, they lower their metabolism plus have adaptations such as scavenging some oxygen from the water via rectal tissues as well as other chemical activity involving glucose and calcium.

https://www.pbs.org/newshour/science/the-secret-to-turtle-hi...

https://wildlifeinwinter.com/painted-turtle

I have one at home in constant warm water, yet she can see the sky and decides to bruminate on her own: every year around this time, she starts napping in her under water hide for days or weeks at a time.

1 year agoby imglorp

For those thinking freezing could be an option... there's a fair bit more than just avoiding ice crystals.

Medical hypothermia in humans (which is just a few degrees colder) is bounded not really by not by time-cold but by restoring normal temperature too quickly. It turns out mitochondria generate a lot of free oxygen radicals when going hypoxic, and restoring oxygen quickly does the chemical damage that actually causes death - so they restore normal temps over a period of hours. I'd bet that's not the only metabolic cycle deranged by hypercooling.

1 year agoby w10-1

There are no pictures of the frogs in this article. For pictures (of thawed and frozen frogs) you can see: https://shakerlakes.org/frozen-frogs/

1 year agoby sudobash1

cant even call that hibernation. There are other knock on advantages to bieng frozen solid, it would slow down and even kill a lot of infectious microbes.It may convey a certain life extension benifit. And threre is not much behavioral adaptation needed,frog gets chilly, snuggles under a leaf,freezes solid, gets defrosted 8 months later and wakes up hungry and horny, not bad.

1 year agoby metalman

> ...the wood frog’s liver produces large amounts of glucose that flushes into every cell in its body. This syrupy sugar solution prevents the cells from freezing...

All natural, no preservatives added, sweetened frog popsicles! Yummy!

1 year agoby redundantly

I really expected a wood(en) frog here, qualifying truly as a biological miracle. But the wood frogs are cool as well.

1 year agoby soco

Could such a mechanism be used for interstellar travel ?

1 year agoby mathh

How are they thawing from the inside out?

1 year agoby zardo

Ok, this is what you really wanted: https://www.bbc.co.uk/programmes/p091w1b3

1 year agoby olddustytrail

> No heartbeat. No breathing. For the entire winter, the wood frog is like a lump of hard, frigid, icy stone carved in the shape of a frog. But it’s alive, in a state of suspended animation.

I find it hard to grasp what is still alive about the frog. I mean, it's not dead so there must be something happening inside the frozen frog? How does it compare to a dead (and frozen) wood frog?

1 year agoby wkjagt

Someone tell Alcor about this.

1 year agoby epicureanideal

One min video with some frozen frogs https://youtu.be/SSvspDZOVV0

They only seem part frozen - still a bit bendy when touched.

1 year agoby tim333

> Understanding how frogs can do this might provide valuable knowledge to help in the management of high blood sugar in people with diabetes.

Also, space travel!

1 year agoby rendall

>Also, the wood frog's ability to withstand freezing may help researchers discover how human organs used for transplants could be frozen and thawed without damage. This would increase the allowable time between removing an organ from a donor and implanting it within the recipient, which could make many more transplants possible.

While certainly some good would come of this, imagine the unintented consequences of such an advancement, especially in a world with stark income inequality.

1 year agoby javajosh

looking at wikipedia, there is more information:

> Frogs can survive many freeze/thaw events during winter if no more than about 65% of the total body water freezes

https://en.wikipedia.org/wiki/Wood_frog#Cold_tolerance

1 year agoby m463

I hope the frogs don't feel pain... Imagine getting frozen alive and extremely slowly.

1 year agoby LoveMortuus

reminds me of the New Avengers episode "the eagle's nest" https://www.imdb.com/title/tt0659325/

1 year agoby croisillon

Nicely written article. A few pictures could have made it more interesting.

1 year agoby the_arun

Fascinating phenomena, thanks a lot for sharing!