From a young age we are taught that, unlike us, reptiles, amphibians and fish are "cold-blooded". A recent discussion in class left me wondering about this difference.
Humans, along with other mammals and birds, are endotherms, which means that they keep their body at a metabolically favourable temperature through internal bodily functions.
Reptiles, amphibians and fish are ectotherms, and rely on environmental heat sources to regulate their body temperatures.
The question arose: if an ectotherm (a lizard was our example) and an endotherm (a guinea pig) where put in a freezer, which would die first? As we didn't want to discover the answer experimentally, I decided to use my prior knowledge and some research to come up with an answer.
Certain ectotherms have a special adaption, which allows them to enter a state of torpor. This is when an animal decreases its physiological activity, usually through reducing its metabolic rate and body temperature. This can last for a large range of time: anything from a few hours to a few years. If the ectotherm placed in the freezer was able to enter a state of torpor, there is little doubt that it would out-live its "warm-blooded" counterpart.
If the ectotherm was unable to enter a state of torpor, I believe it is still likely that it would survive longer than the endotherm. When we, as humans, get cold, we start shaking to keep warm, which uses a lot of energy. If we can't move to somewhere warmer soon, we will eventually run out of energy and die. This would be the same in other endotherms, like the guinea pig. The guinea pig's body temperature will probably also be at a higher temperature than the lizard's, and so will be more different to the external temperature of the freezer. This will cause the endotherm to lose heat more quickly than the ectotherm.
Therefore, in answer to the question, a guinea pig would probably die in a freezer before a lizard.
Emily Lauterpacht
Biology is complicated for it has involved in a full range of fields, such as biochemistry, clinical medicine, animals, and so on. But I still think advances in biology have benefited people a lot.
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