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292:(Greek poikilos – 'various, spotted', and therme – 'heat) whose internal temperature varies considerably. Poikilotherms have to survive and adapt to environmental stress. One of the most important stressors is temperature change, which can lead to alterations in membrane lipid order and can cause protein unfolding and denaturation at elevated temperatures. It is the opposite of a
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homeotherms and poikilotherms have similar niches, and compete, the homeotherm can often drive poikilothermic competitors to extinction, because homeotherms can gather food for a greater fraction of each day and in more effective, specialized ways (e.g. chimpanzees actively seeking out and collecting army ants with sticks versus the typical poikilotherm sit-and-wait strategy).
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This difference in energy requirement also means that a given food source can support a greater density of poikilothermic animals than homeothermic animals. This is reflected in the predator-prey ratio which is usually higher in poikilothermic fauna compared to homeothermic ones. However, when
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are unable to regulate heat. A behavioral adaptation to combat this is incubation, where to maintain the internal temperatures of eggs, the queen and her workers will incubate the brood almost constantly, by warming their abdomens and touching them to the eggs. The bumblebee generates heat by
506:, although they are homeotherms, thermoregulate using a method termed "temperature cycling" to conserve energy. In hot deserts, they allow their body temperature to rise during the day and fall during the night, adjusting their body temperature to cycle over approximately 6 °C.
697:
Sherwin, C.M. (2010). The
Husbandry and Welfare of Non-traditional Laboratory Rodents. In "UFAW Handbook on the Care and Management of Laboratory Animals", R. Hubrecht and J. Kirkwood (Eds). Wiley-Blackwell. Chapter 25, pp.
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Poikilotherm animals must be able to function over a wider range of temperatures than homeotherms. The speed of most chemical reactions vary with temperature, and in order to function poikilotherms may have four to ten
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Daly, T.J.M., Williams, L.A. and
Buffenstein, R., (1997). Catecholaminergic innervation of interscapular brown adipose tissue in the naked mole-rat (Heterocephalus glaber). Journal of Anatomy, 190: 321-326.
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is generally beyond poikilotherm animals. The metabolism of poikilotherms favors strategies such as sit-and-wait hunting over chasing prey for larger animals with high movement cost. As they do not use their
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are poikilothermic. However some ectotherms remain in temperature-constant environments to the point that they are actually able to maintain a constant internal temperature and are considered
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Steen, J.B, Steen, H. & Stenseth, N.C. (1991): Population
Dynamics of Poikilotherm and Homeotherm Vertebrates: Effects of Food Shortage. OICOS Vol. 60, No 2 (March, 1991), pp 269-272.
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500:. Body volume increases proportionally faster than does body surface, with increasing size; and less body surface area per unit body volume tends to minimise heat loss.
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mounds are usually oriented in a north–south direction so that they absorb as much heat as possible around dawn and dusk and minimise heat absorption around noon.
397:) as a function of core body temperature. The homeotherm has a much higher output, but can only function over a very narrow range of body temperatures.
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323:. It is this distinction that often makes the term "poikilotherm" more useful than the vernacular "cold-blooded", which is sometimes used to refer to
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to heat or cool themselves, total energy requirement over time is low. For the same body weight, poikilotherms need only 5 to 10% of the energy of
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often have much shorter generations than homeotherms: weeks rather than years. Such applies even to animals with similar ecological roles such as
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systems that operate at different temperatures for an important chemical reaction. As a result, poikilotherms often have larger, more complex
483:. They also have their swimming muscles near the center of their bodies instead of near the surface, which minimises heat loss.
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Poikilothermic animals include types of vertebrate animals, specifically some fish, amphibians, and reptiles, as well as many
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are a notable example of this effect, though their complex development is also an important factor in their large genome.
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It is comparatively easy for a poikilotherm to accumulate enough energy to reproduce. Poikilotherms at the same
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Campbell, N. A., Reece, J. B., et al. (2002). Biology. 6th edition. Benjamin / Cummings
Publishing Company.
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Guschina, Irina A.; Harwood, John L. (2006). "Mechanisms of temperature adaptation in poikilotherms".
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Willmer, P., Stone, G., & Johnston, I. A. (2000): Environmental physiology of animals.
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666:"Body size shifts influence effects of increasing temperatures on ectotherm metabolism".
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Cavalier-Smith, T. (1991). "Coevolution of vertebrate genome, cell, and nuclear sizes".
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is considered a poikilothermic state in humans. Poikilothermia is one of the signs of
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is a poikilotherm and is able to function over a wide range of body core temperatures.
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bask in the sun in the early morning and late evening, and seek shelter around noon.
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are able to warm their entire bodies through a heat exchange mechanism called the
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363:), meaning "varied," ultimately from a root meaning "dappled" or "painted," and
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Ryan
Gregory, T. (1 January 2002). "Genome size and developmental complexity".
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Because their metabolism is variable and generally below that of homeothermic
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Britton, S. W.; Atkinson, W. E. (1938). "Poikilothermism in the Sloth".
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means growing to large size in order to reduce heat loss, such as in
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645:. Principal ill. Viola Hildebrand. New York: Wiley. p. 429.
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In medicine, loss of normal thermoregulation is referred to as
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shivering flight muscles even though they are not flying.
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Organism with considerable internal temperature variation
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are some of the rare mammals which are poikilothermic.
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Symposium on the
Evolution of Terrestrial Vertebrates
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451:Some adaptations are behavioral. Lizards and
385:Sustained energy output of a poikilotherm (a
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641:Milton Hildebrand; G. E. Goslow Jr. (2001).
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871:(2009). "3". In Teofilo Lee-Chiong (ed.).
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34:needs attention from an expert in biology
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350:The term derives from
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545:compartment syndrome
569:acute limb ischemia
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315:. Many terrestrial
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321:homeothermic
206:poikilotherm
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139:Kleptothermy
124:Thermolabile
109:Heterothermy
99:Poikilotherm
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535:In medicine
491:sea turtles
440:homeotherms
436:metabolisms
309:vertebrates
301:homeostasis
198:common frog
104:Homeothermy
907:Categories
391:homeotherm
377:Physiology
325:ectotherms
317:ectotherms
294:homeotherm
114:Stenotherm
67:in animals
716:(1): 94.
612:1873-3468
565:REM sleep
498:megafauna
346:Etymology
305:organisms
119:Eurytherm
94:Mesotherm
89:Endotherm
84:Ectotherm
50:July 2016
788:24565842
780:12188045
760:Genetica
747:: 51–86.
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620:16824520
389:) and a
360:ποικίλος
355:poikilos
288:) is an
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730:1374287
698:359-369
557:ethanol
511:Ecology
495:ice-age
467:Termite
423:animals
408:genomes
365:thermos
298:thermal
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559:, and
525:snakes
504:Camels
453:snakes
427:flight
404:enzyme
387:lizard
370:θερμός
290:animal
784:S2CID
726:JSTOR
624:S2CID
575:Notes
551:like
481:gills
431:brain
416:Frogs
395:mouse
352:Greek
340:sloth
837:ISBN
806:ISBN
776:PMID
647:ISBN
616:PMID
608:ISSN
523:and
521:cats
493:and
473:Tuna
338:and
196:The
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