Gecko - SV 13B

Geckos are ectotherms!

Geckos are lizards found in warm climates throughout the world. They range from 1.6 to 60 cm. Geckos are unique among lizards in their vocalizations. They use chirping sounds in social interactions with other geckos. They are the most species-rich group of lizards, with about 1,500 different species worldwide.

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Many species are well known for their specialized toe pads that enable them to climb smooth and vertical surfaces, and even cross indoor ceilings with ease (one hypothesis explains the ability in terms of the van der Waals force).

Thermoregulation

Geckos are ectothermic (relying on external heat sources to keep their body temperature at a suitable level) and poikilothermic (having a variable body temperature). A poikilotherm is the opposite of a homeotherm, an organism which maintains thermal homeostasis. Usually the variation is a consequence of variation in the ambient environmental temperature. Many terrestrial ectotherms are poikilothermic.

When exposed to threat of freezing, some poikilotherms actually freeze and are freezing-tolerant; freezing must be limited to the extracellular body fluids, however. Other poikilotherms are freezing-intolerant and exploit one of three strategies—behavioral avoidance, antifreeze production, or supercooling — to avoid freezing. Antifreezes lower the freezing point. Stabilization of supercooling permits animals to remain unfrozen while at temperatures below their freezing points.

So, geckos control their temperature by changing their behavior. E.g. when its internal temperature drops, a lizard will move to find a warmer area, such as a place in the sunshine. When its internal temperature gets too high, it will move to somewhere cooler such as a burrow beneath the sand. This means ectotherms have a variable metabolic rate as they can't keep their internal temperature constant.