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1、两栖类动物的体温调节与哺乳类和鸟类不同，两栖类无法通过新陈代谢产生热量，因此他们无法不受外界周围环境影响地调节体温。然而，两栖类动物一点也不能控制他们的体温的观点是错误的，因为他们他们的体温不总是和周围温度一样。尽管两栖类动物是差劲的温度调节者，他们确实会在有限的程度上对体温进行控制。生理上的调节可以帮助两栖类居住在一些充满极端环境的栖息地中。体温的忍耐范围代表了一个物种可以存活的温度范围。一种北美蝾螈在温度降低到-2时依然能保持活力，而一个南美青蛙在温度高达41时依然很惬意，这是在野外生活的两栖类中被测到的最高体温。最近我们发现一些北美青蛙和蟾蜍物种可以在体温-6时保持三分之一身体冰冻而依然
2、存活。另外的组织被保护，因为他们包含防冻剂甘油或者葡萄糖。此外，一些物种的温度忍耐范围很灵活，可以因为环境适应性而发生改变。尽管会有白天的高温，一些青蛙物种可以保持暴露在太阳中，他们在皮肤结构中有一些很有意思的调节机制，这些结构起到了形态学适应的作用。大部分两栖类动物皮肤是完全可渗水的，因此不能防止蒸发和太阳辐射。非洲草原蛙HV存储鸟嘌呤晶体在皮肤中，使得他们能更好地反射太阳光，因此提供了过热保护。树蛙PS通过腺体分泌物来减少蒸发带来的损失，分泌物在整个皮肤表面形成一个脂肪层，帮助避免失水。但是，行为活动是目前最重要的温度调节的要素。在行为性温度调节方法中主要有晒太阳，和基底热交换比如石头和泥
3、土，白天和每年的躲避行为，包含在白天为了冷却和冬眠或者夏眠而躲到遮蔽物中。天界热调节在青蛙和蟾蜍中是很常见的，这允许它们去增加他们的体温超过10。A蟾蜍在太阳升起以后立刻暴露自己在湿润的土地上通过这种方法来获取合适的温度，而且比地面或者空气达到这样的温度要快很多。这种方法积极的一面是它加速了在晚上捕食的猎物的消化，因此加速了生长。T方法是一种存在于大部分两栖类生物的方法，虽然紧压地面起到两个作用：通过导热体吸收热量和通过皮肤吸收水分。T方法的效果对于下雨中A蟾蜍上特别明显：它的体温等同于温暖泥土的温度而不是更冷的空气。避免性行为会发生在生理和形态适应方法都不足以保持体温在维持生命所必须的温度范
4、围内。对于高的周围温度有很低容忍度的两栖类的夜间活动是一种典型躲避温度管理行为。季节性避免行为对于很多两栖类是特别重要的。栖息地处于温带纬度地区的物种会在冬天面临致命的低温，而在半干旱地区居住的物种会在夏天暴露在漫长干燥时期。对于两栖类来说，冬眠发生在泥土或者远离霜冻深深的洞穴中。P山的北部，N蟾蜍是一个很好的冬眠的例子，通过挖深洞钻入沙子地里渡过寒冬。相反，N蟾蜍在西班牙南部在通常温暖的冬天会保持活力，相反在干旱炎热的夏天被迫休眠。夏眠也发生通过挖地或者躲在凉爽深洞中去躲避干燥和致命的周围温度中。两期类因此很难受到周围环境的影响，因为通过以上阐述的机制的方法他们可以对于体温施加一些控制。Am
5、phibian ThermoregulationIn contrast to mammals and birds, amphibians are unable to produce thermal energy through their metabolic activity, which would allow them to regulate their body temperature independent of the surrounding or ambient temperature. However, the idea that amphibians have no contr
6、ol whatsoever over their body temperature has been proven false because their body temperature does not always correspond to the surrounding temperature. While amphibians are poor thermoregulators, they do exercise control over their body temperature to a limited degree.Physiological adaptations can
7、 assist amphibians in colonizing habitats where extreme conditions prevail. The tolerance range in body temperature represents the range of temperatures within which a species can survive. One species of North American newt is still active when temperatures drop to -2 while one South American frog f
8、eels comfortable even when temperatures rise to 41 the highest body temperature measured in a free-ranging amphibian. Recently it has been shown that some North American frog and toad species can survive up to five days with a body temperature of -6C with approximately one-third of their body fluids
9、 frozen. The other tissues are protected because they contain the frost-protective agents glycerin or glucose Additionally, in many species the tolerance boundaries are flexible and can change as a result of acclimatization (long-term exposure to particular conditions).Frog species that remain expos
10、ed to the sun despite high diurnal (daytime) temperatures exhibit some fascinating modifications in the skin structure that function as morphological adaptations. Most amphibian skin is fully water permeable and is therefore not a barrier against evaporation or solar radiation. The African savanna f
11、rog Hyperolius viridiflavus stores guanine crystals in its skin, which enable it to better reflect solar radiation, thus providing protection against overheating. The tree frog Phyllomedusa sauvagei responds to evaporative losses with gland secretions that provide a greasy film over its entire body
12、that helps prevent desiccation (dehydration).However, behavior is by far the most important factor in thermoregulation. The principal elements in behavioral thermoregulation are basking (heliothermy), heat exchange with substrates such as rock or earth (thigmothermy), and diurnal and annual avoidanc
13、e behaviors, which include moving to shelter during the day for cooling and hibernating or estivating (reducing activity during cold or hot weather, respectively) Heliothermy is especially common among frogs and toads: it allows them to increase their body temperature by more than 10. The Andean toa
14、d Bufo spinulosus exposes itself immediately after sunrise on moist ground and attains its preferred body temperature by this means, long before either ground or air is correspondingly warmed. A positive side effect of this approach is that it accelerates the digestion of the prey consumed overnight
15、, thus also accelerating growth. Thigmothermy is a behavior present in most amphibians, although pressing against the ground serves a dual purpose: heat absorption by conductivity and water absorption through the skin. The effect of thigmothermy is especially evident in the Andean toad during rainfa
16、ll: its body temperature corresponds to the temperature of the warm earth and not to the much cooler air temperature.Avoidance behavior occurs whenever physiological and morphological adaptations are insufficient to maintain body temperature within the vital range. Nocturnal activity in amphibians with low tolerance for high ambient temperatures is a typical thermoregulatory behavior of avoidance. Seasonal avoidance behavior is extremely
