Cold blooded animals are known as ectotherms. These are animals that do not possess the internal regulatory system to control their body temperature. Instead of an internal system, these ectotherms use the heat of the sun that is absorbed by the environment to regulate their body temperature. Some of the more common cold blooded animals are reptiles, amphibians and fish.
A good example of how a cold blooded animal regulates its body temperature is by looking at reptiles. These animals can usually be found lying underneath the heat of the sun in order to absorb heat from the rays of the sun and from the environment around it. The heat will raise the metabolism of the reptiles and will lead to an active period. If the temperature becomes too hot, some reptiles will try to escape the heat by seeking shade – they will find hollows, bury themselves or find a cooler shelter. These reptiles do not have the capability to regulate the heat and lower their body temperatures on their own to acceptable levels. With their internal temperature dropping, their metabolism will also slow down as a way of conserving energy.
Cold blooded animals do not usually need a lot of energy, unlike warm blooded animals (endotherms) that need a lot of energy to regulate their body temperature. For example, snakes are known to eat just one meal in several weeks and the energy they get in one meal will be enough to sustain them in that period of time.