You can freeze nematodes and water bears fairly easily. Notably both of these are evolved to survive dessication and freezing in their normal life cycle and have their largest dimension on the order of one mm. Its a bit of a stretch to call what some frogs can do naturally in the outdoors ‘freezing’ but again, massive evolutionary pressure.
If you try to freeze a complicated structure bigger than a few cubic centimeters that isn’t the ridiculously vascularized and quite small and very homogenous in terms of water content rabbit kidney, you come up with something that is so damaged by the freezing process that it falls apart physically and chemically upon unfreezing. The unfreezing part is not the limiting factor, because there just isn’t a paused functional organism left behind by the freezing process.
You can freeze nematodes and water bears fairly easily. Notably both of these are evolved to survive dessication and freezing in their normal life cycle and have their largest dimension on the order of one mm. Its a bit of a stretch to call what some frogs can do naturally in the outdoors ‘freezing’ but again, massive evolutionary pressure.
If you try to freeze a complicated structure bigger than a few cubic centimeters that isn’t the ridiculously vascularized and quite small and very homogenous in terms of water content rabbit kidney, you come up with something that is so damaged by the freezing process that it falls apart physically and chemically upon unfreezing. The unfreezing part is not the limiting factor, because there just isn’t a paused functional organism left behind by the freezing process.
What about the wood frog?