What makes us warm blooded

Heat escapes from the body through the skin. Layers of clothing help you retain your body heat in the winter. Other mammals must rely on layers of fat or a fur covering to insulate them from the cold and retain their body heat.

A lot of extra food would be required to replace the heat lost from these large surfaces—food that would be extremely hard to find. Smaller animals must produce more heat to keep warm than larger ones. To understand this, pretend that a 3-inch-square box is a small animal and a 6-inch-square box is a larger animal.

On its six exposed sides, the small animal has 54 square inches of skin. The larger animal has square inches of skin, or four times as much. The inside heat-producing area of the small animal is 27 cubic inches, but the inside of the larger animal contains cubic inches, which is eight times bigger.

This means it must produce twice as much heat. Because small bodies must produce so much heat to stay warm, the size of warm-blooded animals is limited. If the animal were too small, it could not digest food fast enough to produce heat as quickly as warmth could be lost through the skin. During the day a tiny hummingbird refuels its furnace with food every ten to fifteen minutes.

Torpor is a type of sleep from which an animal cannot be awakened quickly. Its body temperature drops to that of its surroundings, and the heartbeat and breathing are slowed down greatly. If the temperature drops too low, the animal will freeze and never awaken from torpor. Stuff reader Steve Rencen has wondered that exact same thing, which prompted him to ask us:.

Professor Bill Davison from Canterbury University's School of Biological Sciences is one of New Zealand's leading minds in this area, and he has lent his wisdom to help us answer Steve's query. Davison said all vertebrate animals have a mechanism for detecting temperature, "located in the hypothalamus - a region of the brain - with signals reaching it from internal receptors, monitoring the core temperature, and skin receptors". Read FAQs. Find Pharmacies.

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After hours bulk billed home doctor visits. See a gallery of thermal images of warm- and cold-blooded animals. A crocodile, on the other hand, might live for a year or more. Why the difference? You waste most of the food you eat generating heat.