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{{About|a state of animal dormancy, similar to hibernation}}{{Dormancy}}File:Theba pisana on Foeniculum vulgare, Montbazin, Hérault 03.jpg|thumb|right|Theba pisana snails aestivating on Foeniculum vulgare in Montbazin, FranceFranceAestivation or æstivation (from , summer, but also spelled estivation in American English) is a state of animal dormancy, similar to hibernation, although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered metabolic rate, that is entered in response to high temperatures and arid conditions.BOOK, Miller, William Charles, Trace Fossils: Concepts, Problems, Prospects, Elsevier, 2007, 978-0-444-52949-7, 206,weblink It takes place during times of heat and dryness, the hot dry season, which are often the summer months.Invertebrate and vertebrate animals are known to enter this state to avoid damage from high temperatures and the risk of desiccation. Both terrestrial and aquatic animals undergo aestivation. The fossil record suggests that aestivation may have evolved several hundred million years ago.


Organisms that aestivate appear to be in a fairly "light" state of dormancy, as their physiological state can be rapidly reversed, and the organism can quickly return to a normal state. A study done on Otala lactea, a snail native to parts of Europe and Northern Africa, shows that they can wake from their dormant state within ten minutes of being introduced to a wetter environment.The primary physiological and biochemical concerns for an aestivating animal are to conserve energy, retain water in the body, ration the use of stored energy, handle the nitrogenous end products, and stabilize bodily organs, cells, and macromolecules. This can be quite a task as hot temperatures and arid conditions may last for months. The depression of metabolic rate during aestivation causes a reduction in macromolecule synthesis and degradation. To stabilize the macromolecules, aestivators will enhance antioxidant defenses and elevate chaperone proteins. This is a widely used strategy across all forms of hypometabolism. These physiological and biochemical concerns appear to be the core elements of hypometabolism throughout the animal kingdom. In other words, animals who aestivate appear to go through nearly the same physiological processes as animals that hibernate.JOURNAL, Storey, Kenneth B., Storey, Janet M., 2012, Aestivation: signaling and hypometabolism, The Journal of Experimental Biology, 215, 8, 1425–1433, 10.1242/jeb.054403, 22496277,


File:Kadina-snails-climb-fence-0716.jpg|thumb|right|Introduced Theba pisana snails aestivating on a row of fence posts in Kadina, South AustraliaKadina, South AustraliaFile:Glanum-snail-climb-fence-5763.jpg|thumb|right|Numerous individuals of the snail Cernuella virgata aestivating on a wire fence near Glanum, in the south of FranceFrance


Gastropoda: some air-breathing land snails, including species in the genera Helix, Cernuella, Theba, Helicella, Achatina and Otala, commonly aestivate during periods of heat. Some species move into shaded vegetation or rubble. Others climb up tall plants, including crop species as well as bushes and trees, and will also climb man-made structures such as posts, fences, etc.Their habit of climbing vegetation to aestivate has caused more than one introduced snail species to be declared an agricultural nuisance.To seal the opening to their shell to prevent water loss, pulmonate land snails secrete a membrane of dried mucus called an epiphragm. In certain species, such as Helix pomatia, this barrier is reinforced with calcium carbonate, and thus it superficially resembles an operculum, except that it has a tiny hole to allow some oxygen exchange.{{Citation needed|date=June 2011}}There is decrease in metabolic rate and reduced rate of water loss in aestivating snails like Rhagada tescorum,JOURNAL, Withers, Philip, Pedler, Scott, Guppy, Michael, 1997, Physiological adjustments during aestivation by the Australian land snail Rhagada tescorum (Mollusca: Pulmonata: Camaenidae), Australian Journal of Zoology, 45, 6, 599–611, 10.1071/ZO97009, Sphincterochila boissieri and others.


Insecta: Lady beetles (Coccinellidae) have been reported to aestivate.JOURNAL, Hagen, Kenneth S., 1962, Biology and ecology of predaceous Coccinellidae, Annual Review of Entomology, 7, 289–326, 10.1146/annurev.en.07.010162.001445, Mosquitoes also are reported to undergo aestivation.JOURNAL, Charlwood, JD, Vij, R, Billingsley, PF, 2000, Dry season refugia of malaria-transmitting mosquitoes in a dry savannah zone of east Africa, American Journal of Tropical Medicine and Hygiene, 62, 6, 726–732,weblink False honey ants are well known for being winter active and aestivate in temperate climates. Bogong moths will aestivate over the summer to avoid the heat and lack of food sources.Common, I. F. B. (1954). "A study of the ecology of the adult bogong moth, Agrotis infusa (Boisd) (Lepidoptera: Noctuidae), with special reference to its behaviour during migration and aestivation". Australian Journal of Zoology. 2 (2): 223–263. Adult alfalfa weevils (Hypera postica) aestivate during the summer in the southeastern United States, during which their metabolism, respiration, and nervous systems show a dampening of activity.JOURNAL, Cunningham, R. K., Tombes, A. S., August 1966, Succinate oxidase system in the alfalfa weevil, Hypera postica, during aestivation (summer diapause), Comparative Biochemistry and Physiology, 18, 4, 725–733, 0010-406X, 5967408, JOURNAL, Kutyna, F. A., Tombes, A. S., 1966-11-26, Bioelectric activity of the central nervous system in normal and diapausing alfalfa weevils, Nature, 212, 5065, 956–957, 0028-0836, 6003744, Crustacea: An example of a crustacean undergoing aestivation is with the Australian crab Austrothelphusa transversa , which undergoes aestivation underground during the dry season.JOURNAL, Waltham, Nathan J., Unravelling life history of the Inland Freshwater Crab Austrothelphusa transversa in seasonal tropical river catchments,weblink Australian Zoologist, 38, 2, 217–222, 10.7882/az.2016.034,


Reptiles and amphibians

File:Synchrotron-Reveals-Early-Triassic-Odd-Couple-Injured-Amphibian-and-Aestivating-Therapsid-Share-pone.0064978.s001.ogv|thumb|Aestivation has been put forward as the most likely explanation why this therapsid cynodont Thrinaxodon liorhinus shared its burrow with a temnospondyl amphibian, (Broomistega putterilli]].JOURNAL, Fernandez, V., Abdala, F., Carlson, K. J., Cook, D. C., Rubidge, B. S., Yates, A., Tafforeau, P., Butler, Richard J, 2013, Synchrotron Reveals Early Triassic Odd Couple: Injured Amphibian and Aestivating Therapsid Share Burrow, PLoS ONE, 10.1371/journal.pone.0064978, 8, 6, e64978, 23805181, 3689844, )Non-mammalian animals that aestivate include North American desert tortoises, crocodiles, and salamanders. Some amphibians (e.g. the cane toad and greater siren) aestivate during the hot dry season by moving underground where it is cooler and more humid. The California red-legged frog may aestivate to conserve energy when its food and water supply is low.WEB, Moore, Bob, 29 September 2009, Estivation: The Survial Siesta, Audubon Guides,weblink 5 September 2012, The water-holding frog has an aestivation cycle. It buries itself in sandy ground in a secreted, water-tight mucus cocoon during periods of hot, dry weather. Australian Aborigines discovered a means to take advantage of this by digging up one of these frogs and squeezing it, causing the frog to empty its bladder. This dilute urine—up to half a glassful—can be drunk. However, this will cause the death of the frog which will be unable to survive until the next rainy season without the water it had stored.BOOK, Pough, F. H., Andrews, R. M., Cadle, J. E., Crump, M. L., Savitzky, A. H., Wells, K. D., 2001, Herpetology, second edition, Prentice Hall, Upper Saddle River, New Jersey, The western swamp turtle aestivates to survive hot summers in the ephemeral swamps it lives in. It buries itself in various media which change depending on location and available substrates.BOOK, Burbrige, Andrew, Kuchling, Gerald, 2004, Western swamp tortoise (Pseudemydura umbrina) recovery plan, 3, Dept. of Conservation and Land Management, Perth, Western Australia,weblink PDF, 26 November 2015, Because the species is critically endangered, the Perth Zoo began a conservation and breeding program for it. However, zookeepers were unaware of the importance of their aestivation cycle and during the first summer period would perform weekly checks on the animals. This repeated disturbance was detrimental to the health of the animals, with many losing significant weight and some dying. The zookeepers quickly changed their procedures and now leave their captive turtles undisturbed during their aestivation period.


African lungfish also aestivate.JOURNAL, Delaney, R. G., Lahiri, S., Fishman, A. P., 1974, Aestivation of the African lungfish Protopterus aethiopicus: cardiovascular and respiratory functions, Journal of Experimental Biology, 61, 1, 111–128,weblink PDF, JOURNAL, Fishman, A. P., Galante, R. J., Winokur, A., Pack, A. I., 1992, Estivation in the African lungfish, Proc. Am. Philos. Soc., 136, 1, 61–72, 986798,


Although relatively uncommon, a small number of mammals aestivate.BOOK, McNab, Brian Keith, 2002, The physiological ecology of vertebrates: a view from energetics, Cornell University Press, 978-0-8014-3913-1, 388,weblink Animal physiologist Kathrin Dausmann of Philipps University of Marburg, Germany, and coworkers presented evidence in a 2004 edition of Nature that the Malagasy fat-tailed dwarf lemur hibernates or aestivates in a small tree hole for seven months of the year.JOURNAL, Dausmann, Kathrin H., Glos, Julian, Ganzhorn, Jörg U., Heldmaier, Gerhard, 2004, Physiology: hibernation in a tropical primate, Nature (journal), Nature, 429, 6994, 825–826, 10.1038/429825a, 15215852, According to the Oakland Zoo in California, East African hedgehogs are thought to aestivate during the dry season.WEB, East African Hedgehog, Oakland Zoo,weblink 5 September 2012,weblink" title="">weblink 7 August 2016, yes, dmy-all,

See also



Further reading

  • BOOK, Navas, Carlos Arturo, Carvalho, José Eduardo, 2009, Aestivation: Molecular and Physiological Aspects, Springer, 978-3-642-02420-7,weblink

External links

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