What are an ectotherm an endotherm and a homeotherm?

Answer 1

An ectotherm is an animal that controls its body temperature through external means. As a result of this it is dependant on environmental heat sources (such as basking in the sun) and has a fairly low metabolic rate.

An endotherm is an animal capable of producing heat by internal means (such as a high metabolism).

A homeotherm is able to maintain a stable body temperature through a narrow range.

Most endotherms are therefore homeotherms however some animals considered to be endotherms by definition such as some large fish lack the insulation and thermoregulation to maintain a constant internal body temperature and are therefore not considered homeotherms, but poikilotherms- where the body's temperature changes with the environment.

Some ectotherms, for example tropical marine invertebrates live in warm waters that stay at a constant temperature. Therefore their body temperature does not fluctuate and they are considered ectothermic homeotherms.