"Dragons are scaly, they lay eggs, and they are utterly lacking in any mammalian characteristics. The notion that they are warm blooded is silly." -Aloysius Egon Greegier, armchair dragon scholar "Just like a humanoid to quote three facts, get one of them wrong, and then draw an unrelated conclusion from the lot." - Kacdaninymila, dragon, upon reading Greegier's statement Laypeople, and some scholars, are fond of the terms "cold-blooded" and "warm-blooded" to describe ectothermic and endothermic creatures, respectively. An ectothermic creature lacks the ability to produce its own heat and must depend on its environment for warmth. Most ectothermic creatures seldom actually have cold blood, because they are able to find environmental heat to warm their bodies. An endothermic creature doesn't necessarily have warm blood. What it has is a body temperature that remains more or less steady no matter how hot or cold its surroundings become. Dragons are endothermic. Given their elemental nature, they could hardly be otherwise. A dragon's body temperature depends on its kind and sometimes its age. Dragons that use fire have the highest body temperatures, and dragons that use cold have the lowest. Others have body temperatures that fall between the two extremes. However, when a dragon is deprived of an external heat source, its metabolism and activity level do not change. Unlike a truly ectothermic creature, a dragon can generate its own body heat and its now slowed or forced into hibernation by exposure to cold. tl;dr: It's magic, a wizard did it, I ain't gotta explain s***.