What term describes animals whose body temperature varies with their environment?

The term that describes animals whose body temperature varies with their environment is "ectotherms." Ectothermic animals, often referred to as cold-blooded animals, rely on external sources of heat to regulate their body temperature. This means their body temperature fluctuates with the ambient environmental conditions, such as sunlight and air temperature.

Ectotherms include various species, such as reptiles, amphibians, and many fish. They do not generate significant internal heat, which is a characteristic that distinguishes them from endotherms, or warm-blooded animals, that maintain a constant body temperature regardless of environmental conditions.

This distinction is important in ecology and animal biology, as ectotherms have different behaviors, metabolic rates, and activity patterns compared to endothermic animals, particularly in response to temperature changes in their environments. Understanding this helps explain how these animals adapt and survive in their ecosystems.