An ectotherm is an organism that does not rely strictly upon internal functions to regulate its body temperature. Ectotherms are highly susceptible to harsh changes in environmental temperature. The metabolic rate of these organisms is really low. As a result, these organisms must live areas that are highly consistent in environmental conditions. The main advantage of being an ectotherm over an endotherm is that metabolic process occurs at a much faster rate resulting in less required food uptake. On the other hand, these organisms are rendered practically immobile and most of the time and have to sit and wait for sunlight to come their way. Ectotherms like the lizard pictured above are considered to be “cold-blooded”.