How are they thawing from the inside out?
this seems implausible to me based on how heat generally transfers...
Biological Miracle – Wood Frog
61–70 of 145 posts
Re: Biological Miracle – Wood Frog
#62A 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..."
Re: Biological Miracle – Wood Frog
#63Earlier quoted context omitted.
"frogs don’t freeze once and stay frozen. Instead, they spend a week or two freezing at night and thawing during the day until the temperatures drop permanently below freezing" https://shakerlakes.org/frozen-frogs/
like maple syrup...
Or water… or anything else with a freezing point that the ambient temperature crosses at night
Re: Biological Miracle – Wood Frog
#64Now 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
I would assume that just as a computer’s storage remains intact after a restart, these frogs’ brains have internal structure, synaptic connections etc that are preserved after a freeze/thaw cycle.
That’s a bad assumption though. Based on our inability to bring brains back to life it seems very likely the better comparison is volatile memory like RAM.
Re: Biological Miracle – Wood Frog
#65Earlier quoted context omitted.
I would assume that just as a computer’s storage remains intact after a restart, these frogs’ brains have internal structure, synaptic connections etc that are preserved after a freeze/thaw cycle.
That’s a bad assumption though. Based on our inability to bring brains back to life it seems very likely the better comparison is volatile memory like RAM.
As discussed elsewhere in this thread, butterflies retain some memories formed as caterpillars after every cell in their body changes drastically. They never die but they change immensely and still retain memories, so I'm not sure we know enough to say what good and bad assumptions are here.
Also this should be relatively trivial to test.
Re: Biological Miracle – Wood Frog
#66> 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?
Re: Biological Miracle – Wood Frog
#67> 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…
a chemical reaction that is sensitive to temperature.
Re: Biological Miracle – Wood Frog
#68> 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…
my poor knowledge of biology says it's a deeply unsatisfying "heart beats when enough of the body has thawed for it to beat."
If the heart depends on the brain at all in frogs.
Re: Biological Miracle – Wood Frog
#69> 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…
Maybe something like a bit flip but for neurons happens in the frog's brain from the sun's radiation or something.
Or the elasticity of the heart and muscles.
Re: Biological Miracle – Wood Frog
#70I hope the frogs don't feel pain... Imagine getting frozen alive and extremely slowly.