They do generate heat. They just do not SPEND energy
specifically on heating their bodies by raising their
metabolisms. This is a form of energy conservation. The
metabolic rate they need to live is not nearly enough to heat
their bodies. An example of spending energy to heat the body is
seen in humans shivering. Here muscle is activated not for its
usual purpose, but to function as a furnace. "Warm-blooded" and
"cold-blooded" is somewhat a misnomer. The correct way to think
of it is... Endotherm or ectotherm. Does the heat primarily come
from within (endo) or from the surroundings (ecto). Endothermic
animals include mammals. Most of their body heat is generated by
their own metabolisms. Ectothermic animals include reptiles and
insects. They absorb most of their body heat from the
surroundings. This is not the same as saying they let their body
temperature fluctuate with their surroundings, some avoid this
by moving around to accomodate themselves. Homeotherm or
poikilotherm. Homeotherms want to maintain home