Editing Aestivation

{{Short description|State of animal dormancy taking place in the summer}}
{{About|a state of animal dormancy, similar to hibernation}}
{{Use dmy dates|date=July 2020}}
{{Dormancy}}
[[File:Theba pisana on Foeniculum vulgare, Montbazin, Hérault 03.jpg|thumb|right|''[[Theba pisana]]'' snails aestivating on ''[[Foeniculum vulgare]]'' in [[Montbazin]], France]]

'''Aestivation''' ({{langx|la|aestas}} (summer); also spelled '''estivation''' in [[American and British English spelling differences|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.<ref>{{cite book |last=Miller |first=William Charles |title=Trace Fossils: Concepts, Problems, Prospects |publisher=Elsevier |year=2007 |isbn=978-0-444-52949-7 |page=206 |url=https://books.google.com/books?id=FLDKUSoFmHMC&pg=PA206}}</ref> It takes place during times of heat and dryness, 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. Fossil records suggest that aestivation may have evolved several hundred million years ago.

==Physiology==

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 [[macromolecule]]s. This can be quite a task as hot temperatures and arid conditions may last for months, in some cases for years. The depression of metabolic rate during aestivation causes a reduction in macromolecule synthesis and degradation. To stabilise the macromolecules, aestivators will enhance antioxidant defenses and elevate [[Chaperone (protein)|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 which aestivate appear to go through nearly the same physiological processes as animals that hibernate.<ref>{{cite journal |last1=Storey |first1=Kenneth B. |last2=Storey |first2=Janet M. |year=2012 |title=Aestivation: signaling and hypometabolism |journal=[[The Journal of Experimental Biology]] |volume=215 |issue=8 |pages=1425–1433 |doi=10.1242/jeb.054403 |pmid=22496277|doi-access=free }}</ref>

==Invertebrates==
[[File:Kadina-snails-climb-fence-0716.jpg|thumb|right|Introduced ''[[Theba pisana]]'' snails aestivating on a row of fence posts in [[Kadina, South Australia]]]]
[[File: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 [[France]].]]

===Mollusca===
'''[[Gastropoda]]''': some air-breathing [[land snail]]s, including species in the genera ''[[Helix (gastropod)|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 human-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 (gastropod)|operculum]], except that it has a tiny hole to allow some oxygen exchange.{{Citation needed|date=June 2011}}

There is a decrease in [[metabolic rate]] and [[Desiccation tolerance#Reducing rate of water loss|reduced rate of water loss]] in aestivating snails like ''[[Rhagada tescorum]]'',<ref>{{cite journal |last1=Withers |first1=Philip |last2=Pedler |first2=Scott |last3=Guppy |first3=Michael |year=1997 |title=Physiological adjustments during aestivation by the Australian land snail ''Rhagada tescorum'' (Mollusca: Pulmonata: Camaenidae) |journal=[[Australian Journal of Zoology]] |volume=45 |issue=6 |pages=599–611 |doi=10.1071/ZO97009}}</ref> ''[[Sphincterochila boissieri]]'' and others.

===Arthropoda===
'''[[Insecta]]''': Lady beetles ([[Coccinellidae]]) have been reported to aestivate.<ref>{{cite journal |last=Hagen |first=Kenneth S. |year=1962 |title=Biology and ecology of predaceous Coccinellidae |journal=[[Annual Review of Entomology]] |volume=7 |pages=289–326 |doi=10.1146/annurev.en.07.010162.001445}}</ref> Another type of beetle (''[[Blepharida rhois]])'' also chooses to aestivate. They usually do so when the temperature is warmer and will re-emerge in the late summer or early fall.<ref>{{Cite journal |last=Strauss |first=Sharon Y. |date=1997 |title=Lack of Evidence for Local Adaptation to Individual Plant Clones or Site by a Mobile Specialist Herbivore |url=https://www.jstor.org/stable/4221578 |journal=Oecologia |volume=110 |issue=1 |pages=77–85 |doi=10.1007/s004420050135 |jstor=4221578 |pmid=28307471 |bibcode=1997Oecol.110...77S |issn=0029-8549}}</ref> Mosquitoes also are reported to undergo aestivation.<ref>{{cite journal |last1=Charlwood |first1=JD |last2=Vij |first2=R |last3=Billingsley |first3=PF |year=2000 |title=Dry season refugia of malaria-transmitting mosquitoes in a dry savannah zone of east Africa |journal=[[American Journal of Tropical Medicine and Hygiene]] |volume=62 |issue=6 |pages=726–732 |doi=10.4269/ajtmh.2000.62.726 |pmid=11304064 |url=http://www.ajtmh.org/content/62/6/726.long|doi-access=free }}</ref> False honey ants are well known for being [[Insect winter ecology|winter active]] and aestivate in temperate climates. [[Bogong moth]]s will aestivate over the summer to avoid the heat and lack of food sources.<ref>{{cite journal | last1 = Common | first1 = I. F. B. | year = 1954 | title = 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 | journal = Australian Journal of Zoology | volume = 2 | issue = 2| pages = 223–263 | doi = 10.1071/zo9540223 }}</ref> 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.<ref>{{Cite journal|last1=Cunningham|first1=R. K.|last2=Tombes|first2=A. S.|date=August 1966|title=Succinate oxidase system in the alfalfa weevil, Hypera postica, during aestivation (summer diapause)|journal=Comparative Biochemistry and Physiology|volume=18|issue=4|pages=725–733|issn=0010-406X|pmid=5967408|doi=10.1016/0010-406x(66)90207-6}}</ref><ref>{{Cite journal|last1=Kutyna|first1=F. A.|last2=Tombes|first2=A. S.|date=1966-11-26|title=Bioelectric activity of the central nervous system in normal and diapausing alfalfa weevils|journal=Nature|volume=212|issue=5065|pages=956–957|issn=0028-0836|pmid=6003744|doi=10.1038/212956a0|bibcode=1966Natur.212..956K|s2cid=4205279}}</ref>

'''[[Crustacean|Crustacea]]''': An example of a crustacean undergoing aestivation is with the Australian crab ''[[Austrothelphusa transversa]],'' which undergoes aestivation underground during the dry season''.''<ref>{{Cite journal|last=Waltham|first=Nathan J.|title=Unravelling life history of the Inland Freshwater Crab Austrothelphusa transversa in seasonal tropical river catchments|journal=Australian Zoologist|volume=38|issue=2|pages=217–222|doi=10.7882/az.2016.034|year=2016|doi-access=free}}</ref>

==Vertebrates==
===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]]''.<ref>{{cite journal |last1=Fernandez |first1=V. |last2=Abdala |first2=F. |last3=Carlson |first3=K. J. |last4=Cook |first4=D. C. |last5=Rubidge |first5=B. S. |last6=Yates |first6=A. |last7=Tafforeau |first7=P.|editor1-link=Richard J. Butler |editor1-last=Butler |editor1-first=Richard J  |year=2013 |title=Synchrotron Reveals Early Triassic Odd Couple: Injured Amphibian and Aestivating Therapsid Share Burrow |journal=PLOS ONE |doi=10.1371/journal.pone.0064978 |volume=8 |issue=6 |pages=e64978 |pmid=23805181 |pmc=3689844|bibcode=2013PLoSO...864978F |doi-access=free }}</ref>]]
Non-mammalian animals that aestivate include [[Desert tortoise|North American desert tortoises]], [[crocodile]]s, and [[salamander]]s. 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.<ref>{{cite web |last=Moore |first=Bob |date=29 September 2009 |title=Estivation: The Survival Siesta |publisher=[[Audubon Guides]] |url=http://www.audubonguides.com/article.html?id=27 |access-date=5 September 2012 |archive-date=21 November 2018 |archive-url=https://web.archive.org/web/20181121010717/http://www.audubonguides.com/article.html?id=27 |url-status=dead }}</ref>

The [[Cyclorana platycephala|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 Aboriginals]] 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.<ref>{{cite book |last1=Pough |first1=F. H. |last2=Andrews |first2=R. M. |last3=Cadle |first3=J. E. |last4=Crump  |first4=M. L. |last5=Savitzky  |first5=A. H. |last6=Wells |first6=K. D. |year=2001 |title= Herpetology, second edition |publisher=Prentice Hall |location=Upper Saddle River, New Jersey}}</ref>

The [[Pseudemydura umbrina|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.<ref>{{cite book |last1=Burbrige |first1=Andrew |last2=Kuchling |first2=Gerald |date=2004 |title=Western swamp tortoise (Pseudemydura umbrina) recovery plan |edition=3 |publisher=Dept. of Conservation and Land Management |location=Perth, Western Australia |url=http://www.environment.gov.au/system/files/resources/6221a7a7-b2ef-4aa1-b9d8-f61df10eda2d/files/p-umbrina.pdf|access-date=26 November 2015}}</ref> 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. {{Citation needed|date=May 2024}}

===Fish===
[[African lungfish]] also aestivate<ref>{{cite journal |last1=Delaney |first1=R. G. |last2=Lahiri |first2=S. |last3=Fishman |first3=A. P. |year=1974 |title=Aestivation of the African lungfish ''Protopterus aethiopicus'': cardiovascular and respiratory functions |journal=[[Journal of Experimental Biology]] |volume=61 |issue=1 |pages=111–128 |doi=10.1242/jeb.61.1.111 |pmid=4411892 |url=http://jeb.biologists.org/content/61/1/111.full.pdf}}</ref><ref>{{cite journal |last1=Fishman |first1=A. P. |last2=Galante |first2=R. J. |last3=Winokur |first3=A. |last4=Pack |first4=A. I. |year=1992 |title=Estivation in the African lungfish |journal=[[Proc. Am. Philos. Soc.]] |volume=136 |issue=1 |pages=61–72 |jstor=986798}}</ref> as can [[salamanderfish]].

===Mammals===
Although relatively uncommon, a small number of mammals aestivate.<ref>{{cite book |last=McNab |first=Brian Keith |year=2002 |title=The physiological ecology of vertebrates: a view from energetics |publisher=Cornell University Press |isbn=978-0-8014-3913-1 |page=388 |url=https://books.google.com/books?id=C31HhT7phT0C&pg=PA388}}</ref> Animal physiologist Kathrin Dausmann of [[Philipps University of Marburg]], Germany, and coworkers presented evidence in a 2004 edition of ''[[Nature (journal)|Nature]]'' that the [[Madagascar|Malagasy]] [[fat-tailed dwarf lemur]] hibernates or aestivates in a small tree hole for seven months of the year.<ref>{{cite journal |last1=Dausmann |first1=Kathrin H. |last2=Glos |first2=Julian |last3=Ganzhorn |first3=Jörg U. |last4=Heldmaier |first4=Gerhard |year=2004 |title=Physiology: hibernation in a tropical primate |journal=[[Nature (journal)|Nature]] |volume=429 |issue=6994 |pages=825–826 |doi=10.1038/429825a |pmid=15215852|bibcode=2004Natur.429..825D |s2cid=4366123 }}</ref> According to the Oakland Zoo in California, [[four-toed hedgehog]]s are thought to aestivate during the dry season.<ref>{{cite web |title=East African Hedgehog |publisher=[[Oakland Zoo]] |url=http://www.oaklandzoo.org/East_African_Hedgehog.php |access-date=5 September 2012 |archive-url=https://web.archive.org/web/20160807085802/http://www.oaklandzoo.org/East_African_Hedgehog.php |archive-date=7 August 2016 |url-status=dead}}</ref>

== See also ==
* [[Critical thermal maximum]]
* [[Hibernation induction trigger]]
* [[Siesta]]
* [[Torpor]]
* [[Splooting]]

==References ==
{{Reflist}}

==Further reading==
* {{cite book |last1=Navas |first1=Carlos Arturo |last2=Carvalho |first2=José Eduardo |year=2009 |title=Aestivation: Molecular and Physiological Aspects |publisher=Springer |isbn=978-3-642-02420-7 |url=https://books.google.com/books?id=jukgezrNdCsC}}

==External links==
{{Commons category}}
{{Wiktionary}}
* [http://www.publish.csiro.au/paper/ZO9680857.htm Abstract of an Australian paper on aestivation in snails]
* [http://www.publish.csiro.au/paper/ZO9680857.htm Some info in aestivation in the snail ''Theba pisana'']
* [http://www.fhcrc.org/about/ne/news/2005/04/21/roth.html Hibernation on demand]
* [https://web.archive.org/web/20080725225919/http://library.thinkquest.org/TQ0312800/estivation.htm Basic definition]

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