7. Ectotherm

          This is a picture of a snake. A snake is an example of an ectotherm. An ectotherm is an animal that cannot control its internal body temperature, so it depends on external sources of energy to regulate body temperature. All reptiles, fish, amphibians, and invertebrates are ectotherms, including snakes. Snakes and other ectotherms have to use outside sources to regulate body temperature, so they are often active during the day in order to make use of the sun’s warmth.