Answer:
Endotherms & ectotherms
Most animals need to maintain their core body temperature within a relatively narrow range.
Endotherms use internally generated heat to maintain body temperature. ...
Ectotherms depend mainly on external heat sources, and their body temperature changes with the temperature of the environment.
Explanation: For these animals, heat comes from outside (ecto-) their bodies—their environment provides their warmth. That means they require less food, and are consequently able to inhabit places that would be off-limits to endotherms.
Endotherm, so-called warm-blooded animals; that is, those that maintain a constant body temperature independent of the environment. The endotherms primarily include the birds and mammals; however, some fish are also endothermic.
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