Fascinating animal adaptations: six unique ways wild species have evolved to survive

What exactly does this mean? For most animals, freezing themselves would puncture blood vessels and cut off the circulation of oxygen. But wood frogs have adapted to remain frozen for up to eight months of the year. In the first few weeks, ice fills their abdominal cavity and forms between their layers of skin and muscle. While this happens, the frog's liver produces large amounts of glucose, which prevents their cells from freezing and binds water molecules to prevent dehydration. So, while ice forms on the outsides of their organs and cells, the insides of their cells are protected.

When they're hibernating, wood frogs have no heartbeat and do not breathe. In spring, once they thaw, their hearts start beating again. This adaptation allows them to become active much earlier in the spring than other frogs and to breed in pools of freshly melted water-which would have already dried up if they came out of hibernation later.

Living in the arid deserts of western North America, kangaroo rats don't have much water available to them. These tiny mammals have evolved to eat primarily mesquite beans and grass seeds, which usually provide them with all the water they need, though each gram of seeds contains only half a gram of H2O.

As a result, kangaroo rats' kidneys produce a type of urine that contains very little liquid compared to other mammals. This helps them conserve water for when they need it most, in the hotter and drier summer months. During the summer, kangaroo rats also may eat insects and vegetation as an extra water source.