<P> Animal body temperature control varies by species, so the terms "warm - blooded" and "cold - blooded" (though still in everyday use) suggest a false idea of there being only two categories of body temperature control, and are no longer used scientifically . </P> <P> In general, warm - bloodedness refers to three separate categories of thermoregulation . </P> <Ul> <Li> Endothermy is the ability of some creatures to control their body temperatures through internal means such as muscle shivering or increasing their metabolism (Greek: ἔνδον endon "within" θέρμη thermē "heat"). Some writers restrict the meaning of endothermy to mechanisms that directly raise the animal's metabolic rate to produce heat . The opposite of endothermy is ectothermy . </Li> <Li> Homeothermy maintains a stable internal body temperature regardless of external influence and temperatures . The stable internal temperature is often higher than the immediate environment (Greek: ὅμοιος homoios "similar", θέρμη thermē "heat"). The opposite is poikilothermy . Mammals and birds are homeothermic . </Li> <Li> Tachymetabolism maintains a high "resting" metabolism (Greek: ταχύς tachys / tachus "fast, swift", μεταβάλλειν metaballein "turn quickly"). In essence, tachymetabolic creatures are "on" all the time . Though their resting metabolism is still many times slower than their active metabolism, the difference is often not as large as that seen in bradymetabolic creatures . Tachymetabolic creatures have greater difficulty dealing with a scarcity of food . </Li> </Ul> <Li> Endothermy is the ability of some creatures to control their body temperatures through internal means such as muscle shivering or increasing their metabolism (Greek: ἔνδον endon "within" θέρμη thermē "heat"). Some writers restrict the meaning of endothermy to mechanisms that directly raise the animal's metabolic rate to produce heat . The opposite of endothermy is ectothermy . </Li>

Explain the meaning of the terms cold blooded and warm blooded