is an animal
that does not control it's body temperature through metabolic
regulation. Ectotherms depend largely on external sources of heat, such as solar radiation
. As the environmental temperature increases, the animal's metabolic rate will increase.
Lizards, fish, and amphibians are examples of ectotherms.
Whereas an endotherm will use up to 98% of its energy for heat production an
ectotherm has all this energy available for activity, growth and repair, and reproduction.