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What does "cold-blooded" mean?

What does

What Does “Cold-Blooded” Mean?

When referring to humans, the phrase “cold-blooded” is typically used to describe a person with a cruel or callous personality. But when referring to animals in general, “cold-blooded” refers to the animal’s method of regulating their body temperature. “Cold-blooded” does NOT mean that these animals have cold blood.

“Warm-blooded” means that the animal’s nervous system automatically controls its body temperature regardless of environmental conditions. Another word for “warm-blooded” is endothermic — birds and mammals are endotherms.

“Cold-blooded” means that the animal is unable to automatically control its body temperature. Instead, body temperature is dependent on the temperature of its environment. Another word for “cold-blooded” is ectothermic — invertebrates, fish, amphibians, and reptiles are ectotherms.

How does this affect the way we keep exotic pets?


Invertebrates are extremely diverse. Some have wings, some have venom, some live underwater, and that’s just the tip of the iceberg when it comes to all of the amazing adaptations that they have made to live just about anywhere on our planet. This makes making any kind of broad generalization rather difficult.

Fortunately, there’s a much smaller set of invertebrates that are commonly kept as pets (mantids, tarantulas, scorpions, etc.). Some of these invertebrates seem to regulate their body temperature via basking, while others stick to a preferred microclimate. When preparing to care for a pet invertebrate, make sure to research heating and temperature needs for that particular species and set up the enclosure accordingly.


Amphibians are very unique animals. They spend their youth underwater like fish, then change their entire anatomy through metamorphosis to spend the rest of their lives primarily on land. Although they lose their gills by adulthood, one of the fishlike characteristics that they do keep is how they thermoregulate. Most amphibians don’t bask — instead, they just have a preferred range of temperatures and stick to a certain microclimate within that range.

Changes in temperature affect neurological, muscular, and digestive function in amphibians. When they are kept consistently too hot, they overheat and die. They are generally better at handling cooler temperatures, but temperatures that are persistently too cool are also likely to become fatal. In preparing to care for a pet amphibian, make sure to research appropriate heating and temperatures for the particular species you’re interested in, and set up the enclosure accordingly.


Reptiles are a little more proactive in thermoregulation than invertebrates and amphibians. Rather than simply staying in an area with comfortable temperatures, they make use of the varying temperatures present in their environment to increase and decrease their metabolism at will. However, if restricted to an environment that is consistently too hot, a reptile will overheat and die. If restricted to an environment that is consistently too cool, a reptile will gradually stop eating, get sick, and eventually die.

Different reptile species have different ranges of temperatures that they need in order to effectively regulate their metabolism, and these temperature ranges are dependent on the nature of their native habitat. While preparing to care for a pet reptile, make sure to research the optimal temperature gradient (basking temperatures as well as cool zone temperatures) so you can set up the enclosure appropriately.

If you have or are planning to take home a pet reptile, amphibian, or invertebrate, one of the most valuable tools you can have is the right kind of thermometer. Digital probe thermometers are versatile and enable you to monitor temperature in a particular location. For best results, get two and place the probes on the warm and cool areas of the enclosure. Infrared thermometer (aka temp guns) are also useful if you have a reptile, because their point-and-shoot functionality enables you to check the exact temperature anywhere in the enclosure. When you know the temperatures in your enclosure, you become better equipped to take care of your pet.

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  • Josh Halter


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What a shame ----  you do not have permission to view this page : D