Ectotherm

An ectotherm is an animal whose body temperature varies with the temperature of its surroundings; any animals except birds and mammals. They are considered cold blooded animals and cannot regulate their own body temperature. As a result from this these animals must depend on an environmental heat source to survive and have relatively low metabolic rates. This is a pictures of turtles which are ectotherm since they must bask in the sun (like many reptiles) like they appear to be since that is how they regulate their body heat through sun light's heat.

Source:
Ectotherm. (October 3, 2006) biology-online.org. Retrieved on August 30, 2011,from
http://www.biology-online.org/dictionary/Ectotherm