Can any animals survive freezing?
Ellen Husain takes a look at the animals that can survive freezing
In nature, water crystallises to form ice at about 0°C and it is largely this, rather than temperature, that poses a mortal danger. When ice forms, cells are ruptured by the expansion, or pierced by the growth of sharp crystals.
How do animals survive freezing temperatures?
Many insects prevent ice forming by dehydrating their bodies. North America’s wood frog can famously go weeks below zero and withstand –14°C, because its blood is high in natural cryoprotectants such as urea, glycerol and glycogen. These work like antifreeze, bonding so strongly with water molecules that they cannot bond with each other to form ice crystals.
Can any mammals survive freezing?
The only mammal able to cool below zero is the Arctic ground squirrel. During an eight-month hibernation, its core temperature falls to –2.9°C. It survives by ‘supercooling’ itself, so that water in its body is unable to form crystals around a nucleus and freeze solid.
Main image: Arctic ground squirrel © Getty Images
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