JAMB - Biology (2018 - No. 62)

Insects, fish, reptiles and amphibians are cold blooded because their body temperature changes along with the external temperature which are known as poikilothermic, while birds and mammals are warm blooded because they maintain a high body temperature regardless of the external temperature.

  A poikilothermic is an animal whose internal temperature varies considerably. It is the opposite of a homoeothermic, an animal which maintains thermal homeostasis