這邊要提到的是TPO出現過的North American wood frog,
Special proteins in their blood, called nucleating proteins, cause the water in the blood to freeze first. This ice, in turn, sucks most of the water out of the frog's cells.
At the same time the frog's liver starts making large amounts of glucose—a type of sugar—which packs into cells and props them up.
The frogs enter a state of suspended animation. Inside the cells there's thick sugary syrup, while outside the cells all the water is frozen.
The concentrated sugar solution helps prevent additional water from being pulled out of the frog's cells, which can destroy them.
The peculiar thing is even though the sun is warming the frog up on the outside, its inside thaw out first, the heart and brain and everything. But somehow it all just happens that way every spring.