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.
Polar bears are a good example of this phenomenon. They have large, compact bodies with relatively small surface areas from which they can lose their internally produced heat. This is an important asset in cold climates. In addition, they have heavy fur and fat insulation that help retain body heat.