Generally, cold-blooded animals don’t use their own energy to warm themselves and maintain their bot temperature. Warm-blooded animals heat themselves with energy from food, so they need to eat more regularly tan cold-blooded animals. They only two warm-blooded groups are mammals and birds. Reptiles, amphibians, fish and invertebrates are cold-blooded.
Many cold-blooded animals increase and control their temperature by basking in the sun. Others, especially the invertebrates, require their environment to be warm enough before that are able to move quickly. Many cold-blooded animals need to hibernate if they are to survive cold winters.
Stuart Hine, Manager of the Angela Marmont Centre for UK Biodiversity, National History Museum