âº a gradual process of change and development. âº biology Evolution is the process by which the physical characteristics of types of creatures change over time, new types of creatures develop, and others disappear. (Definition of âevolutionâ from the Cambridge Academic Content Dictionary Â© Cambridge University Press)
You can remember the difference between endotherms and ectotherms if you remember that endo- means inside endo- = inside and ecto- means outside ecto- = outside, so endotherms generate their own heat from within, and ectotherms get their heat from the outside.
Reptiles are poikilothermic-which means that their body temperature alters with the surrounding environmental temperature. The reason for this is that they do not generate and maintain body heat internally, but rely on external heat sources-ie they are ectothermic creatures-hence the common description cold-blooded.