Cold Blooded

To kick off my blog, I thought I’d write a quick breakdown on the basics of what reptiles are known for the best, being “cold blooded”.

What is being "Cold Blooded"?

Being “cold blooded” is referring to an organism that gets their energy from the sun. It is a blanket term for many different adaptations that go into making an animal "cold blooded", which are otherwise known as being ectothermic, exothermic, poikilothermic, or a combination.

• Ectothermic – an organism that regulates body temperature by exchanging heat with the surrounding environment.
• Exothermic – a process which releases heat.
• Poikilothermic – having body temperature which varies with the environment.

Reptiles are actually not the only “cold blooded” animals in the Kingdom, to name a few: amphibians, fish, some mammals, and technically some birds are all “cold blooded” in some way.
An organism can be a poikilotherm, but not ectothermic. Likewise, they can be ecothermic, but not a poikilotherm, but that out of the scope of my knowledge.
Exothermic technically refers to a chemical process and is often swapped out for ectothermic, although I have a suspicion that exothermic can also refer to the role of heat in the metabolic process.

Food, Heat, and Energy

Mammals and birds have to eat in order to maintain their body temperature. Endothermic organisms gain body heat through the chemical processes used in metabolizing their food, which means energy stored in the food is being lost in the process. Ectothermic organisms who only use external heat to metabolize their food and the stored energy in their bodies means reptiles lose no energy in the metabolic process, making them more efficient.

Reptiles don’t have to eat to maintain their body temperature, unlike humans, who need to keep a constant body temperature of 98-100 degrees. As humans, if your core temperature drops below 95, then you’re considered to be going into hypothermia. Anything north of 105 degrees is heat stroke. Reptiles can survive in climates as low as 50 degrees, some reptiles can survive in upwards of 120 degree heat. Some amphibians hibernate through below freezing temperature and emerge to breed the following spring.

This energy model is brilliant for reptiles and amphibians. The environment largely determines the activity of a reptile. If it's warm outside, they burn more energy faster, but also have more energy to hunt as there are more feeding opportunities around in spring and summer such as fruit, insects, mice, whatever their diet may be. In winter, the lack of heat means they are burning less stored energy and likely live in a climate where food becomes scarce in the colder months.

Reptiles rule!