Keeping cold in the winter is good for you - if you?re a frog that is. According to Glenn J. Tattersall and Robert G. Boutilier of the University of Cambridge, writing in the Journal of Experimental Biology [February 1999], frogs that have become acclimatised to low winter temperatures recover more quickly after a bout of enforced exercise if the water is a chilly 1.5 °C than when it is warmer. So there is no need to worry about the well-being of frogs caught under the ice in your neighbourhood pond. If disturbed, and made to swim, they will even seek out a colder part of the pond to recover in.
Unlike mammals and birds, which generate heat internally to keep their body temperatures constant, the body temperature of an amphibian depends very much on that of the surrounding water. The common European frog, Rana temporaria, often has to spend part of the winter submerged under the ice in ponds and lakes. In these conditions it ?breathes? through its skin, rather than its lungs. But far from lapsing into a complete state of cold-induced torpor under these conditions, Rana can remain quite active and still needs to be able to swim to escape from predators.
This is a preview of subscription content, access via your institution