Comparison Chart
Comparing an Endotherm and an Ectotherm

Ectotherm
Monarch Butterfly

Body can generate own heat; does not rely on surrounding environment.

Constantly has a warm body 24 hours a day, 365 days a year (24/365) so can be active any time and in any place, regardless of surrounding environment.

Can be active instantly to escape from predators.

Can be active day or night.

Can search for food almost any time or temperature.

Requires less energy to survive.

Does not spend food energy to maintain a constant body temperature.

Can survive in places where food is scarce or absent.

Can significantly slow down body processes to conserve energy and/or live off fat reserve.

Can go long periods of time without food.

Must spend energy constantly to keep body warm, 24 hours a day and 365 days a year.

Cannot go long periods of time without food.

Needs 3-10 times more food to survive than an ectotherm (of same body mass).

Body can be an invitingly warm place for bacteria, viruses and parasites; can have more problems with infection.

Cannot generate enough of own heat; often relies on surrounding environment to generate heat.

Cannot be active in a cold environment. Muscles are paralyzed by cold temperatures.

May need to bask and/or shiver to raise muscle temperature so can be active.