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Basking Baja California Collared Lizard
Medium: acrylic on illustration board
Year Produced: 2003
Dimensions in inches (H x W): 9" x 12"
Increasingly, designers of indoor temperature regulation systems are
studying the temperature regulation strategies of poikilotherms (animals
whose body temperature varies with the ambient temperature). Reptiles like
the collared lizards (Crotaphytus spp.) commonly alternate between basking
and burrowing, but for the Rubber Boa (Charina bottae) and others that
function best at low temperatures, life is more of an exercise in avoiding
heat than seeking it. New Zealand's relictual Tuatara (Sphenodon punctatus)
is the most cold-blooded reptile of all, with an optimum body temperature
of around 10
ºC (50ºF). Amphibians tend to have lower optimum body temperatures than reptiles. Heat from muscle contractions is frequently used in thermoregulation. Sphinx moths (family Sphingidae) vibrate their wings on cool evenings in a pre-launch warm-up. As an animal increases in size, its surface area-to-volume ratio decreases, and heat loss slows down. A boxy, half-ton Leatherback Turtle (Dermochelys coriacea) can increase its body temperature significantly simply by swimming. This is assisted by heat exchangers in the reptile's circulatory system that work in the same way as those used in many buildings. Such devices are also present in some sharks, and are most highly-developed in tuna of the genera Thunnus and Katsuwonus. which can maintain a temperature in the swimming muscles of their upper tails about 14ºC (25ºF) higher than the ambient water temperature. Lacking expensive metabolic 'furnaces,' poikilotherms can devote practically all of their energy to foraging and reproducing. Because of this, they tend to be more plentiful than their homeothermic analogs. Since internal chemicals often react differently at different temperatures, poikilotherms depend on redundant chemical systems to function properly at different temperatures. Aside from this, though, the advantages of a steady internal temperature are often exaggerated.
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