Re: How cold can a cold blooded creature get and still survive

The short answer: Yes, other cold blooded creatures can survive temperatures at or below freezing.

Cold blooded creatures are those that can not regulate their own body temperature, represented by reptiles, amphibians, insects and fish. The creature's body temperature is usually controlled by different behaviours - moving into the sun to warm up or into the shade to cool down.

It has been long known that in the winter such animals will either migrate or hibernate to protect themselves from extreme cold. Fish were protected by moving into deeper layers of water that did not freeze. Snakes form communal masses in protected crevasses and share warmth all winter. It came as a surprise when fish were found actively swimming around in the Antarctic, where the water temperature was -1.87 degrees C.

It was found that these fish had a special protein - called AFGP (antifreeze glycoprotein) - in the blood that lowered the freezing point of the blood to -2.2 degrees C. A number of other fish species have since been found with the same or similar compounds.

Further research has found the same or similar compounds in many other cold blooded species. These compounds act as an antifreeze or otherwise protect the body from damage from ice formation. There are 11 species of amphibians and reptiles that are known to be able to tolerate the freezing of their tissues. These creatures can actually be fully frozen (70% of their body fluids turned to ice) and show no signs of life, but will return to normal upon warming!

I did not find any specific reference to a snake species with this ability. Most of the species studied have been frogs and turtles.

James Powell