COLD-BLOODEDNESS

also called Poikilothermy, Ectothermy, or Heterothermy, the state of having a variable body temperature that is usually only slightly higher than the environmental temperature. This state distinguishes fishes, amphibians, reptiles, and invertebrate animals from warm-blooded, or homoiothermic, animals (birds and mammals). Because of their dependence upon environmental warmth for metabolic functioning, the distribution of terrestrial cold-blooded animals is limited, with only a few exceptions, to areas with a temperature range of 510 to 3540 C (4150 to 95104 F). For cold-blooded animals living in the arctic seas, temperatures may range from below 0 C to 1015 C (below 32 F to 5059 F). Poikilotherms do maintain a limited control over internal temperature by behavioral means, such as basking in sunlight to warm their bodies.