How wood frogs freeze?

Wood frogs inhabit parts of the U.S., Canada and the Arctic Circle which means, they must be prepared to deal with sub-zero temperatures. While different animals do different things – such as burrowing underground and migrating to warmer places – to escape the cold, creatures such as wood frogs embrace it – they simple freeze! Let’s see how they do it.

They become frogcicles!

When winter arrives and the first ice crystals fall on this freeze-tolerant frog’s skin, the frog begins to freeze. As this happens, the liver starts to produce large quantities of glucose. Once this glucose is released from the liver, it mixes with the bloodstream and is carried throughout the body through the pumping of the heart. Research says urea – produced by the frog’s urine – also blends with the glucose. This mixture helps prevent the cells from freezing completely, because that would mean the death of the frog. Only about 70% of its body fluid freezes. Meanwhile, the frog stops breathing, its heart too stops beating, and organs become inactive. The frog hardens – this is offhandedly referred to as a frogcicle, drawing from the word icicle. The creature is motionless and appears dead. This continues through the winter. While the role of glucose in keeping it alive when it is frozen has been understood, it is still not clear what causes the stopping of a beating heart. As for the frog, when Spring arrives, it begins to thaw, regains consciousness and recovers from its state within a day. And, life goes on – with a freeze-thaw cycle in place.


Picture Credit : Google