# Aestivation

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This article is about a state of animal dormancy, similar to hibernation. For other uses, see [Aestivation (disambiguation)](/source/Aestivation_(disambiguation)).

**Aestivation** (Latin: *aestas* (summer); also **estivation** in [American English](/source/American_and_British_English_spelling_differences)) is a state of animal [dormancy](/source/Dormancy), similar to [hibernation](/source/Hibernation), although taking place in the summer rather than the winter. Aestivation is characterized by inactivity and a lowered [metabolic](/source/Metabolic) rate, that is entered in response to high temperatures and arid conditions.[1] It takes place during times of heat and dryness, which are often the summer months.

Invertebrate and vertebrate animals enter an aestivating state to avoid damage from high temperatures and the risk of [desiccation](/source/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.

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](/source/Macromolecule). 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 proteins](/source/Chaperone_(protein)). 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.[2]

## Invertebrates

### Mollusca

**[Gastropoda](/source/Gastropoda)**: some air-breathing [land snails](/source/Land_snail), including species in the genera *[Helix](/source/Helix_(gastropod)), [Cernuella](/source/Cernuella), [Theba](/source/Theba), [Helicella](/source/Helicella), [Achatina](/source/Achatina)* and *[Otala](/source/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](/source/Epiphragm). In certain species, such as *[Helix pomatia](/source/Helix_pomatia)*, this barrier is reinforced with calcium carbonate, and thus it superficially resembles an [operculum](/source/Operculum_(gastropod)), except that it has a tiny hole to allow some oxygen exchange.[citation needed]

There is a decrease in [metabolic rate](/source/Metabolic_rate) and [reduced rate of water loss](/source/Desiccation_tolerance#Reducing_rate_of_water_loss) in aestivating snails like *[Rhagada tescorum](/source/Rhagada_tescorum)*,[3] *[Sphincterochila boissieri](/source/Sphincterochila_boissieri)* and others.

### Arthropoda

**[Insecta](/source/Insecta)**: Lady beetles ([Coccinellidae](/source/Coccinellidae)) aestivate.[4] Another type of beetle (*[Blepharida rhois](/source/Blepharida_rhois))* also aestivates. They usually do so when the temperature is warmer and will re-emerge in the late summer or early fall.[5] Mosquitoes also are reported to undergo aestivation.[6] False honey ants are well known for being [winter active](/source/Insect_winter_ecology) and aestivate in temperate climates. [Bogong moths](/source/Bogong_moth) will aestivate over the summer to avoid the heat and lack of food sources.[7] Adult alfalfa weevils (*[Hypera postica](/source/Hypera_postica)*) aestivate during the summer in the southeastern United States, during which their metabolism, respiration, and nervous systems show a dampening of activity.[8][9]

**[Crustacea](/source/Crustacean)**: An example of a crustacean undergoing aestivation is with the Australian crab *[Austrothelphusa transversa](/source/Austrothelphusa_transversa),* which undergoes aestivation underground during the dry season*.*[10]

## Vertebrates

### Reptiles and amphibians

Non-mammalian vertebrates that aestivate include [North American desert tortoises](/source/Desert_tortoise), [crocodiles](/source/Crocodile), and [salamanders](/source/Salamander). Some amphibians (e.g. the [cane toad](/source/Cane_toad) and [greater siren](/source/Greater_siren)) aestivate during the hot dry season by moving underground where it is cooler and more humid. The [California red-legged frog](/source/California_red-legged_frog) may aestivate to conserve energy when its food and water supply is low.[11]

The [water-holding frog](/source/Cyclorana_platycephala) 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](/source/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.[12]

The [western swamp turtle](/source/Pseudemydura_umbrina) 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.[13]

### Fish

[African lungfish](/source/African_lungfish) aestivate,[14][15] as can [salamanderfish](/source/Salamanderfish).

### Mammals

Although relatively uncommon, a small number of mammals aestivate.[16] Animal physiologist Kathrin Dausmann of [Philipps University of Marburg](/source/Philipps_University_of_Marburg), Germany, and coworkers presented evidence in a 2004 edition of *[Nature](/source/Nature_(journal))* that the [Malagasy](/source/Madagascar) [fat-tailed dwarf lemur](/source/Fat-tailed_dwarf_lemur) hibernates or aestivates in a small tree hole for seven months of the year.[17] According to the Oakland Zoo in California, [four-toed hedgehogs](/source/Four-toed_hedgehog) are thought to aestivate during the dry season.[18]

## See also

- [Critical thermal maximum](/source/Critical_thermal_maximum)
- [Hibernation induction trigger](/source/Hibernation_induction_trigger)
- [Siesta](/source/Siesta)
- [Torpor](/source/Torpor)
- [Splooting](/source/Splooting)

## References

1. Miller, William Charles (2007). [*Trace Fossils: Concepts, Problems, Prospects*](https://books.google.com/books?id=FLDKUSoFmHMC&pg=PA206). Elsevier. p. 206. ISBN 978-0-444-52949-7.

1. Storey, Kenneth B. & Storey, Janet M. (2012). "Aestivation: signaling and hypometabolism". *[The Journal of Experimental Biology](/source/The_Journal_of_Experimental_Biology)*. **215** (8): 1425–1433. [Bibcode:2012JExpB.215.1425S](https://ui.adsabs.harvard.edu/abs/2012JExpB.215.1425S). [doi:10.1242/jeb.054403](https://doi.org/10.1242/jeb.054403). [PMID 22496277](https://pubmed.ncbi.nlm.nih.gov/22496277)

1. 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](/source/Australian_Journal_of_Zoology)*. **45** (6): 599–611. [doi:10.1071/ZO97009](https://doi.org/10.1071/ZO97009)

1. Hagen, Kenneth S. (1962). "Biology and ecology of predaceous Coccinellidae". *[Annual Review of Entomology](/source/Annual_Review_of_Entomology)*. **7**: 289–326. [doi:10.1146/annurev.en.07.010162.001445](https://doi.org/10.1146/annurev.en.07.010162.001445)

1. Strauss, Sharon Y. (1997). "Lack of Evidence for Local Adaptation to Individual Plant Clones or Site by a Mobile Specialist Herbivore". *Oecologia*. **110** (1): 77–85. [Bibcode:1997Oecol.110...77S](https://ui.adsabs.harvard.edu/abs/1997Oecol.110...77S). [doi:10.1007/s004420050135](https://doi.org/10.1007/s004420050135). [ISSN 0029-8549](https://www.worldcat.org/issn/0029-8549). [JSTOR 4221578](https://www.jstor.org/stable/4221578). [PMID 28307471](https://pubmed.ncbi.nlm.nih.gov/28307471)

1. Charlwood, JD; Vij, R; Billingsley, PF (2000). ["Dry season refugia of malaria-transmitting mosquitoes in a dry savannah zone of east Africa"](http://www.ajtmh.org/content/62/6/726.long). *[American Journal of Tropical Medicine and Hygiene](/source/American_Journal_of_Tropical_Medicine_and_Hygiene)*. **62** (6): 726–732. [doi:10.4269/ajtmh.2000.62.726](https://doi.org/10.4269/ajtmh.2000.62.726). [PMID 11304064](https://pubmed.ncbi.nlm.nih.gov/11304064)

1. 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. [doi:10.1071/zo9540223](https://doi.org/10.1071/zo9540223)

1. 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. [doi:10.1016/0010-406x(66)90207-6](https://doi.org/10.1016/0010-406x(66)90207-6). [ISSN 0010-406X](https://www.worldcat.org/issn/0010-406X). [PMID 5967408](https://pubmed.ncbi.nlm.nih.gov/5967408)

1. 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. [Bibcode:1966Natur.212..956K](https://ui.adsabs.harvard.edu/abs/1966Natur.212..956K). [doi:10.1038/212956a0](https://doi.org/10.1038/212956a0). [ISSN 0028-0836](https://www.worldcat.org/issn/0028-0836). [PMID 6003744](https://pubmed.ncbi.nlm.nih.gov/6003744). [S2CID 4205279](https://api.semanticscholar.org/CorpusID:4205279)

1. Waltham, Nathan J. (2016). "Unravelling life history of the Inland Freshwater Crab Austrothelphusa transversa in seasonal tropical river catchments". *Australian Zoologist*. **38** (2): 217–222. [doi:10.7882/az.2016.034](https://doi.org/10.7882/az.2016.034)

1. Moore, Bob (29 September 2009). ["Estivation: The Survival Siesta"](http://www.audubonguides.com/article.html?id=27). [Audubon Guides](/source/Audubon_Guides). [Archived](https://web.archive.org/web/20181121010717/http://www.audubonguides.com/article.html?id=27) 21 November 2018 at the Wayback Machine. Retrieved 5 September 2012.

1. Pough, F. H.; Andrews, R. M.; Cadle, J. E.; Crump, M. L.; Savitzky, A. H.; Wells, K. D. (2001). *Herpetology, second edition*. [Prentice Hall](/source/Prentice_Hall)

1. Burbrige, Andrew & Kuchling, Gerald (2004). [*Western swamp tortoise (Pseudemydura umbrina) recovery plan*](http://www.environment.gov.au/system/files/resources/6221a7a7-b2ef-4aa1-b9d8-f61df10eda2d/files/p-umbrina.pdf). 3 ed. Perth, Western Australia: Dept. of Conservation and Land Management. Retrieved 26 November 2015.

1. Delaney, R. G.; Lahiri, S.; Fishman, A. P. (1974). ["Aestivation of the African lungfish *Protopterus aethiopicus*: cardiovascular and respiratory functions"](http://jeb.biologists.org/content/61/1/111.full.pdf). *[Journal of Experimental Biology](/source/Journal_of_Experimental_Biology)*. **61** (1): 111–128. [Bibcode:1974JExpB..61..111D](https://ui.adsabs.harvard.edu/abs/1974JExpB..61..111D). [doi:10.1242/jeb.61.1.111](https://doi.org/10.1242/jeb.61.1.111). [PMID 4411892](https://pubmed.ncbi.nlm.nih.gov/4411892)

1. Fishman, A. P.; Galante, R. J.; Winokur, A.; Pack, A. I. (1992). "Estivation in the African lungfish". *[Proceedings of the American Philosophical Society](/source/Proceedings_of_the_American_Philosophical_Society)*. **136** (1): 61–72. [JSTOR 986798](https://www.jstor.org/stable/986798)

1. McNab, Brian Keith (2002). [*The physiological ecology of vertebrates: a view from energetics*](https://books.google.com/books?id=C31HhT7phT0C&pg=PA388). Cornell University Press. p. 388. ISBN 978-0-8014-3913-1.

1. Dausmann, Kathrin H.; Glos, Julian; Ganzhorn, Jörg U.; Heldmaier, Gerhard (2004). "Physiology: hibernation in a tropical primate". *[Nature](/source/Nature_(journal))*. **429** (6994): 825–826. [Bibcode:2004Natur.429..825D](https://ui.adsabs.harvard.edu/abs/2004Natur.429..825D). [doi:10.1038/429825a](https://doi.org/10.1038/429825a). [PMID 15215852](https://pubmed.ncbi.nlm.nih.gov/15215852). [S2CID 4366123](https://api.semanticscholar.org/CorpusID:4366123)

1. ["East African Hedgehog"](http://www.oaklandzoo.org/East_African_Hedgehog.php). [Oakland Zoo](/source/Oakland_Zoo). [Archived](https://web.archive.org/web/20160807085802/http://www.oaklandzoo.org/East_African_Hedgehog.php) 7 August 2016 at the Wayback Machine. Retrieved 5 September 2012.

## Further reading

- Navas, Carlos Arturo & Carvalho, José Eduardo (2009). [*Aestivation: Molecular and Physiological Aspects*](https://books.google.com/books?id=jukgezrNdCsC). Springer. ISBN 978-3-642-02420-7.

## External links

- [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.publish.csiro.au/paper/ZO9680857.htm)
- [Hibernation on demand](http://www.fhcrc.org/about/ne/news/2005/04/21/roth.html)
- [Basic definition](https://web.archive.org/web/20080725225919/http://library.thinkquest.org/TQ0312800/estivation.htm)

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