Poikilotherm

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poikilotherm

[pȯi′kil·ə‚thərm]
(zoology)
An animal, such as reptiles, fishes, and invertebrates, whose body temperature varies with and is usually higher than the temperature of the environment; a cold-blooded animal.

Poikilotherm

 

a cold-blooded animal, that is, an animal with a variable body temperature that changes as a function of the temperature of the environment. Poikilotherms include all invertebrates; the only poikilothermic vertebrates are fishes, amphibians, and reptiles.

The body temperature of poikilotherms is generally only 1° or 2° higher than, or equal to, that of the environment. Thermoregulation is imperfect. In many poikilotherms the body temperature rises as a result of muscular work or the absorption of solar heat. For example, the body temperature of bumblebees in flight may reach 38° or even 44°C at an air temperature of 4° to 8°C. However, after the cessation of flight the body cools rapidly to the temperature of the environment. If the external temperature rises above or falls below optimal limits, poikilotherms become torpid or perish. Many of them are in torpor a large part of the year; for example, the turtle Testudo horsfieldi is active only three months of the year. The absence of perfect thermoregulatory mechanisms in poikilotherms may be explained by the relatively poor development of their nervous systems (especially the central nervous system), a level of metabolism approximately 20 to 30 times lower than that of homeo-therms, and other features associated with the fact that poikilotherms have a more primitive organization than birds and mammals.

References in periodicals archive ?
Lags have also been found in the bones of reptiles and amphibians and have until now been assumed to be limited to ectotherms - cold-blooded animals - that are more subject to the whims of harsh environments.
Reports of other shark tumors afflicting nervous, digestive, excretory, blood, reproductive, skeletal, endocrine, and skin tissues--and even cartilage--are on file at a national archive devoted to cancer in cold-blooded animals.
These cold-blooded animals depend on external heat to regulate their body temperature and metabolism (process in which billions of the body's cells release energy stored in food).
Like other cold-blooded animals, these theropods had low metabolic rates while at rest, which is an excellent strategy for conserving energy.
The senseless killing of Monica Lynne Leech in Thousand Oaks reminds us that there is no safety from cold-blooded animals who prey on the defenseless.
They are cold-blooded animals," Karina Paner, an alligator trapper and director at Croc Encounters, told the (http://www.
According to one theory, first proposed in the 1990s, species with higher resting metabolic rates are likely to accumulate DNA changes at a faster rate, especially among cold-blooded animals such as frogs, snakes, lizards and fishes.
They explained that since crocodiles are cold-blooded animals, the temperature of the environment affects their body temperature and metabolic rate.
Cold-blooded animals like reptiles are well-adapted to live in the desert.
Metabolic and lung ventilation rates in cold-blooded animals are about five percent of a similarly sized warm-blooded animal.
org%2Fcontent%2Fearly%2F2016%2F08%2F30%2F1604824113) Proceedings of the National Academy of Sciences has revealed that some of these cold-blooded animals may be much harder hit by climate change than previously believed.
The ability to better control the freezing temperature of supercooled water could be critical for a variety of applications, including the survival of cold-blooded animals, the cryo-preservation of cells and tissues, the protection of crops from freezing, and the ability to understand and trigger cloud formation.