These wood frogs are one of the only creatures that can be described as “the living dead”. Yet every spring they come back to life again.
Unable to travel large distances to escape Canada's winter, wood frogs have developed one of the most incredible survival strategies. They freeze.
As winter comes, they hunker down just under the leaf litter. They begin to produce a special anti-freeze in their blood, made out of glucose and glycogen.
As the temperature continues to drop, this antifreeze is taken up into their cells. Inside each cell, the sugary syrup keeps the cells plump and strong, and prevents ice crystals from forming which would kill them.
When in this frogcicle state, their hearts stop beating and they stop breathing. As much as 70 per cent of the frog's body is frozen solid.
These hardy wood frogs can survive all winter in this suspended animation, undergoing several cycles of freezing and thawing as the temperature changes.
When the weather warms, the frogs thaw and emerge to begin their chorus, signalling the start of Canadian spring.
Scientists are learning more about how wood frogs freeze and thaw in the hopes of one day improving organ transplants for humans.