#cold-blooded-animals

Warm-blooded animals, such as birds and mammals, and known as endotherms, generate their own heat and maintain a body temperature independent of the environment. Cold-blooded animals, known as ectotherms, include amphibians, reptiles, invertebrates and most fish.

Endothermy is the ability of some creatures to control their body temperatures through internal means such as muscle shivering or increasing their metabolism (Greek: endon = "within", thermē = "heat"). Some writers restrict the meaning of endothermy to mechanisms that directly raise the animal's metabolic rate in order to produce heat. The opposite of endothermy is ectothermy.

Homeothermy maintains a stable internal body temperature regardless of external influence and temperatures. This stable internal temperature is often, though not necessarily, higher than the immediate environment (Greek: homoios = "similar", thermē = "heat"). The opposite is poikilothermy. Mammals and birds are Homeothermic animals.