Word of the Day:

: an organism (as a frog) with a variable body temperature that tends to fluctuate with and is similar to or slightly higher than the temperature of its environment : a cold-blooded organism

The environment controls the body temperature of poikilotherms, although they can heat and cool themselves by moving in and out of the sun.

Poikilotherms are also called "ectotherms" or "cold-blooded animals." Such creatures are the thermoregulatory opposites of "endotherms" or "homeotherms" -- better known to most of us as "warm-blooded animals" -- which are able to maintain a fairly high and constant body temperature relatively independent of the temperature of the surroundings. "Stenotherms" are creatures that can survive only within a very narrow temperature range. The "-therm" in all of these terms comes from the Greek "thermē," which means "heat."