Alaskan

From Ai Gemini:

The Alaskan wood frog (Lithobates sylvaticus) has a remarkable ability to freeze solid in the winter and then thaw out and return to normal in the spring.

Here's how they do it:

- Natural Antifreeze: When temperatures drop, the wood frog's liver produces large amounts of glucose (sugar). This glucose acts like a natural antifreeze, flooding into the cells and preventing them from freezing and becoming damaged.
- Controlled Freezing: While the cells themselves are protected, the water outside the cells and around the organs does freeze. Their eyes can turn white, and ice crystals form between layers of skin and muscle.
- Suspended Animation: During this frozen state, the frog exhibits no signs of life: no muscle movement, no heartbeat, and no breathing. They are essentially in a state of suspended animation.
- Thawing and Revival: In the spring, as temperatures rise, the frog thaws from the inside out. Their heart starts beating again, then the brain activates, and finally, their legs move. They emerge completely undamaged by conditions that would be fatal to most other animals.

This incredible adaptation allows the wood frog to survive in extremely cold environments, including north of the Arctic Circle, and be one of the first amphibians to emerge and breed in the spring. Scientists are even studying this ability to learn more about cryopreservation and its potential applications, such as for organ transplants.