View source for Crayfish

{{short description|Freshwater crustaceans}}
{{redirect|Crawfish}}
{{use dmy dates|date=March 2023}}
{{Paraphyletic group
| auto = yes
| fossil_range = {{fossil range|Triassic|recent|earliest=Permian}}
| image = Paranephrops.jpg
| image_caption = ''[[Paranephrops]]'' species ([[Parastacidae]])
| parent = Astacidea
| includes_text = [[Superfamily (taxonomy)|Superfamilies]] and [[Family (biology)|families]]
| includes = ;[[Astacoidea]]
* [[Astacidae]]
* [[Cambaridae]]
* [[Cambaroididae]]
;[[Parastacoidea]]
* [[Parastacidae]]
}}
[[File:Crayfish at Cynrig Hatchery.webm|thumb|Rearing white-clawed crayfish at Cynrig hatchery, [[Wales]]. Establishing a breeding population from introduced captive-bred animals.]]
[[File:Crawfish.jpg|thumb|Cajun style crawfish]]
[[File:A man selling dried crayfish in african market.jpg|thumb|Dried crayfish at an African market]]

'''Crayfish'''{{efn|In some locations, they are also known as '''baybugs''', '''crabfish''', '''craws''', '''crawfish''',  '''crawdaddies''', '''crawdads''', '''freshwater lobsters''',  '''mountain lobsters''', '''mudbugs''', '''rock lobsters''',  or '''yabbies'''.}} are freshwater [[crustacean]]s belonging to the infraorder [[Astacidea]], which also contains [[lobster]]s. Taxonomically, they are members of the [[Superfamily (taxonomy)|superfamilies]] [[Astacoidea]] and [[Parastacoidea]]. They breathe through feather-like [[gill]]s. Some species are found in brooks and streams, where  [[fresh water]] is running, while others thrive in [[swamp]]s, ditches, and [[paddy fields]]. Most crayfish cannot tolerate [[Water pollution|polluted water]], although some species, such as ''[[Procambarus clarkii]]'', are hardier. Crayfish feed on animals and plants, either living or [[decomposing]], and [[detritus]].<ref>{{cite book |author1 = Christoph Needon |author2 = Johannes Petermann |author3 = Peter Scheffel |author4 = Bernd Scheibe |title = Plants and Animals (Pflanzen und Tiere) |publisher = Urania Verlag |location = Leipzig |year = 1971 }}</ref>

The term "crayfish" is applied to saltwater species [[#Other animals|in some countries]].

== Terminology ==

The name "crayfish" comes from the [[Old French language|Old French]] word ''{{lang|fro|escrevisse}}'' ([[French language|Modern French]] ''{{lang|fr|écrevisse}}'').<ref name="OED">{{Cite OED|crayfish}}</ref><ref>{{cite journal |last = Wedgwood |first = Hensleigh |author-link = Hensleigh Wedgwood |title = On False Etymologies |journal = Transactions of the Philological Society |url = https://babel.hathitrust.org/cgi/pt?id=uc1.b3924121;view=1up;seq=75 |year = 1855 |issue = 6 |page = 65 }}</ref> The word has been modified to "crayfish" by association with "fish" ([[folk etymology]]).<ref name="OED"/> The largely [[American English|American]] variant "crawfish" is similarly derived.<ref name="OED"/>

Some kinds of crayfish are known locally as [[lobster]]s,<ref>{{cite journal |author = C. W. Hart Jr. |s2cid = 86017542 |year = 1994 |title = A dictionary of non-scientific names of freshwater crayfishes (Astacoidea and Parastacoidea), including other words and phrases incorporating crayfish names |journal = [[Smithsonian Contributions to Anthropology]] |volume = 38 |issue = 38 |pages = 1–127 |doi = 10.5479/si.00810223.38.1 |hdl = 10088/1372 }}</ref> crawdads,<ref name="Bayou">{{cite web |title = Mudbug Madness: Crawfish |author = Pableaux Johnson |url = http://www.bayoudog.com/articles/kitchen_stories/mudbug_madness_crawfish.php |publisher = Bayou Dog |access-date = 28 August 2006 |archive-url = https://web.archive.org/web/20060819231829/http://www.bayoudog.com/articles/kitchen_stories/mudbug_madness_crawfish.php |archive-date = 19 August 2006 }}</ref> mudbugs,<ref name="Bayou"/> and [[Cherax|yabbies]]. In the [[Eastern United States]], "crayfish" is more common in the north, while "crawdad" is heard more in central and southwestern regions, and "crawfish" farther south, although considerable overlaps exist.<ref>{{cite web |author1 = Bert Vaux |author2 = Scott A. Golder |url = http://www4.uwm.edu/FLL/linguistics/dialect/staticmaps/q_66.html |title = Dialect survey |publisher = [[Harvard University]] |access-date = 30 September 2006 }}</ref>

The study of crayfish is called astacology.<ref>{{cite web |url = http://147.72.68.29/crayfish/IAA/ |archive-url = https://web.archive.org/web/20050405165844/http://147.72.68.29/crayfish/IAA/ |archive-date = 5 April 2005 |title = About the International Association of Astacology }}</ref>

== Anatomy ==
{{Main|Decapod anatomy}}

The body of a [[Decapoda|decapod]] [[crustacean]], such as a crab, lobster, or prawn (shrimp), is made up of twenty [[body segment]]s grouped into two main body parts, the [[cephalothorax]] and the [[Abdomen#Arthropoda|abdomen]]. Each segment may possess two pairs of [[appendage]]s, although in various groups, these may be reduced or gone. On average, crayfish grow to {{convert|17.5|cm|in|abbr=on}} in length. Walking legs have a small claw at the end.<ref>{{Cite web |title = What Is the Difference Between Walking Legs and Chelipeds in Crayfish? |url = https://animals.mom.com/what-is-the-difference-between-walking-legs-and-chelipeds-in-crayfish-12563006.html |access-date = 12 June 2021 |website = Pets on Mom.com |language = en }}</ref>

==Diet==
Crayfish are opportunistic [[omnivorous]] scavengers, with the ability to filter and process mud.<ref name="OBrien1990">{{cite journal |last=O'Brien |first=Brett G. |title=Feeding Biology of Marron Cherax tenuimanus Decapoda: Parastacidae |journal=National Symposium of Freshwater Crayfish Culture Proceedings |date=1990 |pages=89–104}}</ref> In [[aquaculture]] ponds using [[isotope analysis]] they were shown to build body tissue selectively from the animal protein portion of pelleted food and not the other components of the pellet.<ref name="OBrienDavies2002">{{cite journal |last1=O'Brien |first1=B.G. |last2=Davies |first2=P.M. |title=The structure of marron ''(Cherax tenuimanus)'' food webs in commercial ponds: results from multiple stable isotope analyses. |journal=Freshwater Crayfish |date=2002 |volume=13 |issue=1 |pages=155–163}}</ref>
  
They have the potential to eat most foods, even nutrient poor material such as grass, leaves, and paper, but can be highly selective and need variety to balance their diet. The personalities of the individual crayfish can be a key determinant in the food preference behaviour in aquaria.{{cn|date=December 2023}}

Crayfish all over the world can be seen in an [[ecological]] role of [[benthic]] dwellers, so this is where most of their food is obtained – at the sediment/water interface in ponds, lakes, swamps, or burrows. When the gut contents are analysed, most of the contents is mud: fine particulate organic matter (FPOM) and mixed particles of lignin and cellulose (roots, leaves, bark, wood).<ref name="OBrien1995">{{cite journal |last1=O'Brien |first1=Brett G. |title=The natural diet of the freshwater crayfish ''Cherax tenuimanus'' (Smith 1912) (Decapoda: Parastacidae) as determined by gut content analysis. |journal=Freshwater Crayfish |date=1995 |volume=10 |issue=1 |pages=151–162}}</ref> Some animal material can also be identified, but this only contributes a small portion of the diet by volume. 

They feed on submerged vegetable material at times, but their ability to catch large living animal material is restricted. They can feed on [[interstitial fauna|interstitial organisms]] if they can be grasped in the small feeding claws. They can be lured into traps with an array of baits from dog biscuits, fish heads, meat, etc., all of which reinforces the fact that they are generalist feeders. 

On a day-to-day basis, they consume what they can acquire in their immediate environment in limited space and time available - [[detritus]]. At a microbial level, the FPOM has a high surface area of organic particles and consists of a plethora of [[Substrate (marine biology)|substrate]] and [[bacteria]], [[fungi]], [[micro-algae]], [[meiofauna]], partially decomposed organic material and mucus. This mucus or "slime" is a [[biofilm]] and can be felt on the surface of leaves and sticks. Also crayfish have been shown to be [[coprophagic]] – eating their own faeces, they also eat their own [[exuviae]] ([[moult]]ed [[carapace]]) and each other.<ref name="OBrienDavies2002"/> They have even been observed leaving the water to graze.<ref>{{Cite journal |last1=Grey |first1=Jonathan |last2=Jackson |first2=Michelle C. |date=2012-08-03 |editor-last=Carlson |editor-first=Stephanie M. |title='Leaves and Eats Shoots': Direct Terrestrial Feeding Can Supplement Invasive Red Swamp Crayfish in Times of Need |journal=PLOS ONE |language=en |volume=7 |issue=8 |article-number=e42575 |doi=10.1371/journal.pone.0042575 |issn=1932-6203 |pmc=3411828 |pmid=22880039 |doi-access=free |bibcode=2012PLoSO...742575G |quote=Isotopic analysis confirmed limited nocturnal observations that these individuals were consuming living terrestrial plants}}</ref>

Detritus or mud is a mixture of dead [[plankton]] (plant and animal), organic wastes from the [[water column]], and debris derived from the aquatic and terrestrial environments. Mostly detritus is in the end phase of decomposition and is recognised as black organic mud. The crayfish usually ingest the material in only a few minutes, as distinct from grazing for many hours. The material is mixed with digestive fluids and sorted by size. The finer particles follow a slower and more exacting route through to the [[hindgut]], compared to the coarser material. The coarser material is eliminated first and often reappears in approximately 10 to 12 hours, whereas the finer material is usually eliminated from 16 to 26 hours after ingestion.<ref name="O'Brien1994">{{cite book |last=O'Brien |first=Brett G. |title=The Feeding Biology of Marron |date=1994 |publisher=The University of Western Australia |page=273}}</ref>

All waste products coming out through the hindgut are wrapped in a [[peritrophic membrane]], so they look like a tube. Such an investment in the wrapping of the microbial free faeces in a protein rich membrane is most likely the reason they are coprophagic. Such feeding behaviour based on selection, ingestion, and extreme processing ensures periodic feeding, as distinct from continuous grazing. They tend to eat to satiation and then take many hours to process the material, leaving minimal chance of having more room to ingest other items. Crayfish usually have limited home range and so they rest, digest, and eliminate their waste, most commonly in the same location each day.

Feeding exposes the crayfish to risk of predation, and so feeding behaviour is often rapid and synchronised with feeding processes that reduce such risks – eat, hide, process and eliminate.

Knowledge of the diet of these creatures was considered too complex since the first book ever written in the field of zoology, ''The Crayfish'' by [[T.H. Huxley]] (1879), where they were described as "[[detritivores]]". This is why most researchers have not attempted to understand the diet of freshwater crayfish. The most complex study which matched the structure and function of the whole digestive tract with ingested material was performed in the 1990s by Brett O'Brien on [[marron]],<ref name="O'Brien1994"/> the least aggressive of the larger freshwater crayfish with aquaculture potential, similar to redclaw and yabbies.

== Classification and geographical distribution ==

{{Multiple image
| header = Three families of crayfish
| width = 220
| direction = vertical
| align = right
| image1 = Austropotamobius pallipes.jpg
| caption1 = [[Astacidae]]: ''[[Austropotamobius pallipes]]''
| image2 = FloridaFlusskrebs.JPG
| caption2 = [[Cambaridae]]: ''[[Procambarus alleni]]''
| image3 = Cherax destructor (Cyan yabby).jpg
| caption3 = [[Parastacidae]]: ''[[Cherax destructor]]''
}}
[[File:Crayfish near Kita-Kamakura staion - Kanagawa - 20250621.webm|thumb|Various crayfish in the wild in [[Kanagawa Prefecture|Kanagawa]], [[Japan]]]]

Crayfish are closely related to [[lobsters]], and together they belong to the [[infraorder]] [[Astacidea]]. Their [[phylogeny]] can be shown in the simplified [[cladogram]] below:<ref name="Wolfe2019">{{cite journal |last1 = Wolfe |first1 = Joanna M. |last2 = Breinholt |first2 = Jesse W. |last3 = Crandall |first3 = Keith A. |last4 = Lemmon |first4 = Alan R. |last5 = Lemmon |first5 = Emily Moriarty |last6 = Timm |first6 = Laura E. |last7 = Siddall |first7 = Mark E. |last8 = Bracken-Grissom |first8 = Heather D. |title = A phylogenomic framework, evolutionary timeline and genomic resources for comparative studies of decapod crustaceans |journal = Proceedings of the Royal Society B |date = 24 April 2019 |volume = 286 |issue = 1901 |doi = 10.1098/rspb.2019.0079 |pmc = 6501934 |pmid = 31014217 |doi-access = free }}</ref><ref name=Crandall2017>{{Cite journal |title = An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list |date = 2017 |last1 = Crandall |first1 = Keith A. |last2 = De Grave |first2 = Sammy |journal = Journal of Crustacean Biology |volume = 37 |issue = 5 |pages = 615–653 |doi = 10.1093/jcbiol/rux070 |doi-access = free }}</ref><ref name="Bracken2014">{{cite journal |author1 = Heather D. Bracken-Grissom |author2 = Shane T. Ahyong |author3 = Richard D. Wilkinson |author4 = Rodney M. Feldmann |author5 = Carrie E. Schweitzer |author6 = Jesse W. Breinholt |author7 = Matthew Bendall |author8 = Ferran Palero |author9 = Tin-Yam Chan |author10=Darryl L. Felder |author11 = Rafael Robles |author12 = Ka-Hou Chu |author13 = Ling-Ming Tsang |author14 = Dohyup Kim |author15 = Joel W. Martin |author16 = Keith A. Crandall |title = The Emergence of Lobsters: Phylogenetic Relationships, Morphological Evolution and Divergence Time Comparisons of an Ancient Group (Decapoda: Achelata, Astacidea, Glypheidea, Polychelida) |journal = [[Systematic Biology]] |date = July 2014 |volume = 63 |issue = 4 |pages = 457–479 |doi = 10.1093/sysbio/syu008 |doi-access = free |pmid = 24562813 |hdl = 10550/106842 |hdl-access = free }}</ref>
{{clade
 |label1=[[Astacidea]]
 |1={{clade
  |label1=clawed lobsters
  |1={{clade
   |label1=[[Enoplometopoidea]]
   |1=[[Enoplometopidae]]
   |label2=[[Nephropoidea]]
   |2=[[Nephropidae]] }}
  |label2='''crayfish'''
  |2={{clade
   |label1=[[Parastacoidea]]
   |1=[[Parastacidae]]
   |label2=[[Astacoidea]]
   |2={{clade
    |1=[[Cambaroididae]]
    |2={{clade
     |1=[[Astacidae]]
     |2=[[Cambaridae]] }} }} }} }} }}

Four [[extant taxon|extant]] (living) [[family (biology)|families]] of crayfish are described, three in the [[Northern Hemisphere]] and one in the [[Southern Hemisphere]]. The Southern Hemisphere ([[Gondwana]]-distributed) family [[Parastacidae]], with 14 extant genera and two extinct genera, live(d) in [[South America]], [[Madagascar]], and [[Australasia]]. They are distinguished by the absence of the first pair of [[pleopod]]s.<ref>{{cite journal |author = Horton H. Hobbs Jr. |s2cid = 86685246 |author-link = Horton H. Hobbs Jr. |year = 1974 |title = Synopsis of the families and genera of crayfishes (Crustacea: Decapoda) |journal = Smithsonian Contributions to Zoology |volume = 164 |issue = 164 |pages = 1–32 |doi = 10.5479/si.00810282.164 }}</ref> Of the other three Northern Hemisphere families (grouped in the [[superfamily (biology)|superfamily]] [[Astacoidea]]), the four genera of the family [[Astacidae]] live in western [[Eurasia]] and western [[North America]], the 15 genera of the family [[Cambaridae]] live in eastern [[North America]], and the single genus of [[Cambaroididae]] live in eastern [[Asia]].<ref name=Crandall2017/>

=== North America === 

The greatest diversity of crayfish species is found in southeastern North America, with over 330 species in 15 genera, all in the family Cambaridae. A further genus of astacid crayfish is found in the [[Pacific Northwest]] and the headwaters of some rivers east of the [[Continental Divide]]. Many crayfish are also found in lowland areas where the water is abundant in [[calcium]], and oxygen rises from underground springs.<ref>{{cite book |author = Steve Pollock |title = Eyewitness Ecology |location = [[New York City|New York]], [[United States]] |publisher = [[Dorling Kindersley]] |year = 2005 |isbn = 978-0-7894-5581-9 |url-access = registration |url = https://archive.org/details/eyewitness00stev }}</ref> Crayfish are also found in some non-coastal wetlands; eight species of crayfish live in [[Iowa]],<ref>{{Cite press release |title=What's a Mudbug? |date=2022-07-12 |publisher=[[Iowa Department of Natural Resources]] |url=https://www.iowadnr.gov/About-DNR/DNR-News-Releases/ArticleID/4127/What-39-s-a-Mudbug}}</ref> for example.

In 1983, [[Louisiana]] designated the crayfish, or crawfish as they are commonly called, as its official state crustacean.<ref name=Profile>{{cite web |url = http://americanprofile.com/articles/the-crawfish-louisianas-state-crustacean/ |title = The Crawfish – Louisiana's State Crustacean |publisher = American Profile |date = 11 August 2002 |access-date = 25 November 2017 }}</ref> Louisiana produces {{convert|100|e6lb|e6kg|abbr=off}} of crawfish per year with the [[Procambarus clarkii|red swamp]] and [[Procambarus zonangulus|white river crawfish]] being the main species harvested.<ref name=SS>{{cite web |url = https://statesymbolsusa.org/symbol-official-item/louisiana/state-fish-aquatic-life-state-food-agriculture-symbol/crawfish |title = Crawfish Louisiana State Crustacean |work = State of Louisiana-Department of Administration |date = 3 June 2014 |access-date = 25 November 2017 }}</ref> Crawfish are a part of [[Cajun]] culture dating back hundreds of years.<ref name=VOA>{{cite web |url = https://www.voanews.com/a/crawfish-deeply-rooted-in-louisiana-culture/3292538.html |title = Crawfish Deeply Rooted in Louisiana Culture |publisher = Voice of America |date = 19 April 2016 |access-date = 25 November 2017 }}</ref> A variety of cottage industries have developed as a result of commercialized crawfish iconography. Their products include crawfish attached to wooden plaques, T-shirts with crawfish logos, and crawfish pendants, earrings, and necklaces made of gold or silver.<ref name=CF>{{cite book |url = https://play.google.com/store/books/details?id=uyD9vkhFlDoC |title = Cajun Foodways |last = Gutierrez |first = C. Paige |publisher = University Press of Mississippi |page = 78 |isbn = 978-1-60473-602-1 |date = 1 January 2012 |access-date = 25 November 2017 }}</ref>

=== Australia ===

[[Australia]] has over 100 species in a dozen [[genus|genera]]. It is home to the world's three largest freshwater crayfish:
* the [[Tasmanian giant freshwater crayfish]] ''Astacopsis gouldi'', which can achieve a mass over {{convert|5|kg|lb|abbr=on}} and is found in rivers of northern [[Tasmania]]<ref>{{cite web |url = http://www.environment.gov.au/biodiversity/threatened/publications/lobster.html |title = Tasmanian Giant Freshwater Lobster (''Astacopsis gouldi'') |publisher = [[Department of the Environment, Water, Heritage and the Arts]] |date = 9 February 2007 |access-date = 16 March 2010 }}</ref>
* the [[Murray crayfish]] ''Euastacus armatus'', which can reach {{convert|2.5|kg|lb|abbr=on}}, although  reports of animals up to {{convert|3|kg|lb|abbr=on}} have been made. It is found in much of the southern [[Murray-Darling basin]].<ref>{{cite web |title = The Murray crayfish – Euastacus armatus as a Vulnerable Species |publisher = NSW Department of Primary Industries |author = Fisheries Scientific Committee |date = 2013 |url = https://www.dpi.nsw.gov.au/__data/assets/pdf_file/0009/545688/FFRS-89_Gilligan-et-al-2007.pdf |archive-url = https://web.archive.org/web/20150401175355/http://www.dpi.nsw.gov.au/__data/assets/pdf_file/0009/545688/FFRS-89_Gilligan-et-al-2007.pdf |archive-date = 1 April 2015 |url-status = live |access-date = 11 March 2019 }}</ref>
* the [[marron]] from [[Western Australia]] (now believed to be two species, ''[[Cherax tenuimanus]]'' and ''[[Cherax cainii|C. cainii]]'') which may reach {{convert|2.2|kg|lb|abbr=on}}

Many of the better-known Australian crayfish are of the genus ''Cherax'', and include the [[common yabby]] (''C. destructor''), western yabby (''C. preissii''), and [[red-claw crayfish]] (''C. quadricarinatus'').<ref>{{cite journal |url = http://aquanic.org/publicat/usda_rac/efs/srac/244fs.pdf |archive-url = https://web.archive.org/web/20050513095955/http://aquanic.org/publicat/usda_rac/efs/srac/244fs.pdf |archive-date = 13 May 2005 |year = 1997 |journal = SRAC Publication |issue = 244 |title = Australian Red Claw Crayfish |author1 = Michael P. Masser |author2 = David B. Rouse }}</ref>

The marron species ''C. tenuimanus'' is [[critically endangered]], while other large Australasian crayfish are threatened or endangered.

=== New Zealand ===

In [[New Zealand]], two species of ''[[Paranephrops]]'' are endemic, and are known by the [[Māori language|Māori]] name ''{{lang|mi|kōura}}''.<ref>{{cite web |url = http://www.niwa.co.nz/our-science/freshwater/tools/kaitiaki_tools/species/koura |title = Kōura |publisher = [[NIWA]] |access-date = 18 September 2012 |date = 26 May 2009 }}</ref>

=== Other animals === 
{{Confuse|Lobster}}

In Australia, New Zealand, and [[South Africa]],<ref>{{cite news |url = http://museum.wa.gov.au/explore/articles/lobsters-rock-lobsters-and-crayfish |title = Lobsters, rock lobsters and crayfish |publisher = Western Australian Museum |access-date = 30 November 2019 }}</ref> the term "crayfish" or "cray" generally refers to a saltwater [[spiny lobster]], of the genus ''[[Jasus]]'' that is indigenous to much of southern [[Oceania]],<ref>{{cite journal |doi = 10.1163/156854065X00613 |title = Let's call the spiny lobster "spiny lobster" |author = Harold W. Sims Jr. |journal = [[Crustaceana]] |volume = 8 |issue = 1 |year = 1965 |pages = 109–110 |jstor = 20102626 |bibcode = 1965Crust...8..109S }}</ref> while the [[freshwater]] species are usually called ''[[Common yabby|yabbies]]'' or ''{{lang|mi|[[Paranephrops|kōura]]}}'', from the [[Indigenous Australian languages|indigenous Australian]] and Māori names for the animal, respectively, or by other names specific to each species. Exceptions include [[Panulirus cygnus|western rock lobster]] (of the [[Palinuridae]] family) found on the west coast of Australia (it is a spiny lobster, but not of ''Jasus)''; the [[Tasmanian giant freshwater crayfish]] (from the [[Parastacidae]] family and therefore a true crayfish) found only in Tasmania; and the [[Murray crayfish]] found along Australia's [[Murray River]].{{Cn|date=February 2021}}

In [[Singapore]], the term crayfish typically refers to ''[[Thenus orientalis]]'', a seawater crustacean from the [[slipper lobster]] family.<ref>{{cite web |title = Sweet Chilli Crayfish (龙马精神) |url = http://www.mywoklife.com/2010/02/sweet-chilli-crayfish.html |date = 13 February 2010 |work = mywoklife.com }}</ref><ref>{{cite web |title = FAR OCEAN SEA PRODUCTS (PRIVATE) LIMITED |url = http://dollarvietnam.com/?Id=EStore&Act=View&Man=Chitiet&DoanhNghiep=farocean&SanPham=3d852a1024073cf53901da4ae1f4b7b2 |work = dollarvietnam.com }}</ref><ref>{{cite book |title = Classic Asian Noodles |publisher = Marshall Cavendish |year = 2007 |url = https://books.google.com/books?id=TsCV6YZXPQoC&pg=PA98 |isbn = 978-981-261-335-6 }}</ref> True crayfish are not native to Singapore, but are commonly found as pets, or as an invasive species (''[[Cherax quadricarinatus]]'') in the many water catchment areas, and are alternatively known as ''freshwater lobsters''.<ref>{{cite journal |doi = 10.1007/s10530-007-9094-0 |title = Feral populations of the Australian Red-Claw crayfish (''Cherax quadricarinatus von Martens'') in water supply catchments of Singapore |author1 = Shane T. Ahyong |author2 = Darren C. J. Yeo |journal = Biol Invasions |volume = 9 |year = 2007 |pages = 943–946 |issue = 8 |bibcode = 2007BiInv...9..943A |doi-access = free }}</ref>

In the United Kingdom and Ireland, the terms crayfish or crawfish commonly refer to the [[Palinurus elephas|European spiny lobster]], a saltwater species found in much of the East Atlantic and Mediterranean.<ref>{{Cite web |title = European spiny lobster (Palinurus elephas) |url = https://www.marlin.ac.uk/species/detail/1145 |url-status = live |access-date = 17 October 2021 |website = The Marine Life Information Network |archive-url = https://web.archive.org/web/20160407175521/http://www.marlin.ac.uk/species/detail/1145 |archive-date = 7 April 2016 }}</ref> The only true crayfish species native to the British Isles is the endangered [[white clawed crayfish]].<ref>{{Cite web |title = White-clawed (or Atlantic stream) crayfish (Austropotamobius pallipes) - Special Areas of Conservation |url = https://sac.jncc.gov.uk/species/S1092/ |access-date = 17 October 2021 |website = sac.jncc.gov.uk }}</ref><ref>{{Cite web|title=White-clawed crayfish {{!}} Shropshire Wildlife Trust|url=https://www.shropshirewildlifetrust.org.uk/wildlife-explorer/invertebrates/crustacea-centipedes-and-millipedes/white-clawed-crayfish|access-date=17 October 2021|website=www.shropshirewildlifetrust.org.uk}}</ref>

== Fossil record ==

Fossil burrows very similar in construction to those of modern crayfish and likely produced by early crayfish are known from the [[Early Permian]] (~300-270 million years ago) of equatorial [[Pangea]], in what is now North America ([[Washington Formation]]), and Europe ([[Sardinia]]). The oldest body fossils assigned to crayfish are known from the [[Late Triassic]] (~230-200 million years ago) [[Chinle Formation]] of North America, assigned to the species "''Enoploclytia''" ''porteri'' and ''Camborygma eumekenomos,'' which are not assigned to any modern families. An indeterminate member of the modern family [[Cambaridae]] is known from the Late Jurassic [[Morrison Formation]] of North America.<ref>{{Cite journal |last1=Audo |first1=Denis |last2=Hasiotis |first2=Stephen T |last3=Kawai |first3=Tadashi |date=2023-12-01 |title=Diversity and evolutionary history of fossil crayfishes |url=https://academic.oup.com/jcb/article/doi/10.1093/jcbiol/ruad079/7504443 |journal=Journal of Crustacean Biology |language=en |volume=43 |issue=4 |doi=10.1093/jcbiol/ruad079 |issn=0278-0372|url-access=subscription }}</ref> The earliest records of other modern families date to the Early Cretaceous, including the [[Parastacidae|parastacid]] ''[[Palaeoechinastacus]]'' from Australia which is 115&nbsp;million years old,<ref>{{Cite journal |last1=Martin |first1=Anthony J. |last2=Rich |first2=Thomas H. |last3=Poore |first3=Gary C.B. |last4=Schultz |first4=Mark B. |last5=Austin |first5=Christopher M. |last6=Kool |first6=Lesley |last7=Vickers-Rich |first7=Patricia |date=2008 |title=Fossil evidence in Australia for oldest known freshwater crayfish of Gondwana |journal=Gondwana Research |volume=14 |issue=3 |pages=287–296 |doi=10.1016/j.gr.2008.01.002 |bibcode=2008GondR..14..287M |issn=1342-937X}}</ref> the [[Cambaroididae|cambaroidid]] ''[[Palaeocambarus]]'' from the [[Yixian Formation]] of China which is likely around 120 million years old ([[Barremian]]-[[Aptian]]),<ref name=":0">{{Cite journal |date=2023 |title=Crayfishes from the Jehol biota |url=https://sciencepress.mnhn.fr/en/periodiques/geodiversitas/45/24 |journal=Geodiversitas |language=en |volume=45 |issue=24 |pages=689–719}}</ref> and the [[Astacidae|astacid]] ''"[[Austropotamobius]]" llopisi'' from the [[Las Hoyas]] site in [[Spain]] (Barremian).<ref>{{Cite journal |last1=García-Penas |first1=Álvaro |last2=Ferratges |first2=Fernando Ari |last3=Moreno-Bedmar |first3=Josep Anton |last4=Bover-Arnal |first4=Telm |last5=Gasca |first5=José Manuel |last6=Aurell |first6=Marcos |last7=Zamora |first7=Samuel |date=2023 |title=Decapod crustaceans from the Lower Cretaceous of Spain, with an account of new occurrences in Barremian-Aptian strata of the Maestrazgo Basin |journal=Cretaceous Research |volume=150 |article-number=105576 |doi=10.1016/j.cretres.2023.105576 |bibcode=2023CrRes.15005576G |issn=0195-6671|doi-access=free }}</ref>

== Threats to crayfish ==

Crayfish are susceptible to infections such as [[crayfish plague]] and to environmental stressors including acidification. In Europe, they are particularly threatened by crayfish plague, which is caused by the North American [[water mold]] ''Aphanomyces astaci.'' This water mold was transmitted to Europe when North American species of crayfish were introduced.<ref name="lee-james"/> Species of the genus ''[[Astacus]]'' are particularly susceptible to infection, allowing the plague-coevolved [[signal crayfish]] (native to western North America) to invade parts of [[Europe]].<ref>{{Cite web |title = Nonindigenous Aquatic Species - Pacifastacus leniusculus |url = https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=200 |access-date = 6 July 2020 }}</ref>

[[Acid rain]] can cause problems for crayfish across the world. In whole-ecosystem experiments simulating acid rain at the [[Experimental Lakes Area]] in [[Ontario|Ontario, Canada]], crayfish populations crashed – probably because their [[exoskeleton]]s are weaker in [[Freshwater acidification|acidified]] environments.<ref>{{Cite web |date = 16 May 2018 |title = A Canadian Scientist Explains How Acid Rain is Still Making its Mark |url = https://www.iisd.org/ela/blog/research-highlights/acid-rain-totally-last-century-right-not-exactly-canadian-scientist-explains-acid-rain-still-making-mark/ |access-date = 6 July 2020 |website = IISD Experimental Lakes Area }}</ref>

== Invasive pest ==

In several countries, particularly in Europe, native species of crayfish are under threat by imported species, particularly the signal crayfish (''[[Pacifastacus leniusculus]]'').<ref>{{Cite web |url = https://blog.invasive-species.org/2019/12/19/invading-europes-waterways-the-crayfish-occupation/ |title = Invading Europe's waterways: The crayfish occupation |date = 19 December 2019 }}</ref><ref>{{Cite web |url = https://theconversation.com/invasive-species-why-britain-cant-eat-its-way-out-of-its-crayfish-problem-147961 |title = Invasive species: Why Britain can't eat its way out of its crayfish problem |date = 13 October 2020 }}</ref> Crayfish are also considered an invasive predatory species, endangering native European species such as the [[Italian agile frog]] and the [[Discoglossus pictus|painted frog]] in [[Malta]].<ref>{{Cite web |date=2024-10-15 |title=4,500 crayfish removed from Chadwick Lakes in two years |url=https://timesofmalta.com/article/4500-crayfish-removed-chadwick-lakes-two-years.1099556 |access-date=2024-10-15 |website=Times of Malta |language=en-gb}}</ref>

== Uses ==

{{Multiple image
| header = Human uses
| width = 220
| direction = vertical
| align = right
| image1 = Crawfish Boil.jpg
| caption1 = Crayfish, boiled with potatoes and corn
| image2 =  Pet-crayfish-(Clippy-II)-in-freshwater-aquarium-with-apple-snail.jpg
| caption2 =  A pet crayfish, ''[[Procambarus clarkii]]'' in a freshwater aquarium
| image3 =  Crayfish Pendant MET DT4899.jpg
| caption3 = Golden crayfish pendant, [[Veraguas culture]], [[Chiriquí Province|Chiriqui]], Panama, c. 11th to 16th century AD
}}

=== Culinary use ===
{{Cookbook|Crawfish}}{{main|Crayfish as food}}

Crayfish are eaten worldwide. Like other edible crustaceans, only a small portion of the body of a crayfish is eaten. In most prepared dishes, such as soups, [[Bisque (food)|bisques]] and [[étouffée]]s, only the tail portion is served. At [[seafood boil|crawfish boils]] or other meals where the entire body of the crayfish is presented, other portions, such as the claw meat, may be eaten.{{Cn|date=February 2021}}

Research shows that crayfish do not die immediately when boiled alive, and respond to pain in a similar way to mammals. Then the stress hormone cortisol is released and this leads to the formation of lactic acid in the muscles, which makes the meat taste sour. Crayfish can be cooked more humanely by first freezing them unconscious for a few hours, then destroying the central nervous system along their abdomen by cutting the crayfish lengthwise with a long knife down the center of the crayfish before cooking it.<ref>{{Cite news |last=Alström |first=Vivvi |date=2023-08-12 |title=Forskning visar: Kräftor känner smärta när de kokas levande |language=sv |work=SVT Nyheter |url=https://www.svt.se/nyheter/inrikes/visst-gor-det-ont-nar-kraftor-kokas |access-date=2023-08-12}}</ref>

Global crayfish production is centered in Asia, primarily China. In 2018, Asian production accounted for 95% of the world's crayfish supply.<ref>{{cite web |title = Global Aquaculture Production: Procambarus clarkii, 1990-2018 |url = http://www.fao.org/figis/servlet/SQServlet?file=/usr/local/tomcat/8.5.16/figis/webapps/figis/temp/hqp_7058869486391224748.xml&outtype=html |website = FAO Fisheries Division |publisher = Food And Agriculture Organization of the United Nations |access-date = 21 March 2021 }}</ref>

Crayfish is part of [[Swedish cuisine]] and is usually eaten in August at special [[Crayfish party|crayfish parties]] ({{langx|sv|Kräftskiva}}). Documentation of the consumption of crayfish dates to at least the 16th century. On the Swedish west coast, [[Nephrops norvegicus]] ({{lang|sv|Havskräfta}}, {{lit|sea crayfish}}) is more commonly eaten while various freshwater crayfish are consumed in the rest of the country. Prior to the 1960s, crayfish was largely inaccessible to the urban population in Sweden and consumption was largely limited to the upper classes or farmers holding fishing rights in fresh water lakes. With the introduction of import of frozen crayfish the crayfish party is now widely practiced across all spheres in Sweden and among the [[Swedish-speaking population of Finland]].<ref>Po Tidhom (2004). "The Crayfish Party". The Swedish Institute. Archived from the original on 4 February 2009. Retrieved 29 January 2006.</ref>

In the United States, crayfish production is strongly centered in [[Louisiana]], with 93% of crayfish farms located in the state as of 2018.<ref>{{cite web |title = Table 18. Crustacean Sales by Species: 2018 and 2013 |url = https://www.nass.usda.gov/Publications/AgCensus/2017/Online_Resources/Aquaculture/aqua_1_0018_0018.pdf |archive-url = https://web.archive.org/web/20191219201907/https://www.nass.usda.gov/Publications/AgCensus/2017/Online_Resources/Aquaculture/aqua_1_0018_0018.pdf |archive-date = 19 December 2019 |url-status = live |website = 2018 Census of Agriculture |publisher = USDA, National Agricultural Statistics Service |access-date = 21 March 2021 }}</ref> In 1987, Louisiana produced 90% of the crayfish harvested in the world, 70% of which were consumed locally.<ref>{{cite journal |year = 1990 |journal = SRAC Publication |issue = 242 |title = Crawfish production: harvesting, marketing and economics |author = Larry W. de la Bretonne Jr. |author2 = Robert P. Romaire |name-list-style = amp |url = http://www.aquanic.org/publicat/usda_rac/efs/srac/242fs.pdf |archive-url = https://web.archive.org/web/20101212111732/http://aquanic.org/publicat/usda_rac/efs/srac/242fs.pdf |archive-date = 12 December 2010 }}</ref> In 2007, the Louisiana crayfish harvest was about 54,800 tons, almost all of it from [[aquaculture]].<ref>{{cite web |url = http://text.lsuagcenter.com/NR/rdonlyres/4687F896-C5C5-47D6-A4F4-1F4455760816/46429/CrawfishHarvestStatistics7807.pdf |archive-url = https://web.archive.org/web/20120402060519/http://text.lsuagcenter.com/NR/rdonlyres/4687F896-C5C5-47D6-A4F4-1F4455760816/46429/CrawfishHarvestStatistics7807.pdf |archive-date = 2 April 2012 |year = 2009 |publisher = Louisiana State University Agricultural Center, Baton Rouge, Louisiana |title = 1978–2007: Louisiana Summary of Agriculture and Natural Resources }}</ref> About 70–80% of crayfish produced in Louisiana are ''[[Procambarus clarkii]]'' (red swamp crawfish), with the remaining 20–30% being ''[[Procambarus zonangulus]]'' (white river crawfish).<ref>{{cite web |url = http://www.lsuagcenter.com/en/our_offices/research_stations/Aquaculture/Features/extension/Classroom_Resources/The+Difference+Between+Red+Swamp+Crawfish+and+White+River+Crawfish.htm |title = Differences Between Red Swamp Crawfish and White River Crawfish |work = The Louisiana State University Agricultural Center |access-date = 25 February 2009 |archive-url = https://web.archive.org/web/20110718211025/http://www.lsuagcenter.com/en/our_offices/research_stations/Aquaculture/Features/extension/Classroom_Resources/The+Difference+Between+Red+Swamp+Crawfish+and+White+River+Crawfish.htm |archive-date = 18 July 2011 }}</ref> Optimum dietary nutritional requirement of freshwater crayfish, or crayfish nutrient specifications are now available for aquaculture feed producers <ref>{{Cite journal |url =  |doi = 10.1038/s41598-020-76692-0 |title = Recycling biofloc waste as novel protein source for crayfish with special reference to crayfish nutritional standards and growth trajectory |year = 2020 |last1 = Lunda |first1 = Roman |last2 = Roy |first2 = Koushik |last3 = Dvorak |first3 = Petr |last4 = Kouba |first4 = Antonin |last5 = Mraz |first5 = Jan |journal = Scientific Reports |volume = 10 |issue = 1 |page = 19607 |pmid = 33177672 |pmc = 7658255 |bibcode = 2020NatSR..1019607L }}</ref>

Like all crustaceans, crayfish are not [[kosher]] because they are aquatic animals that do not have both [[fin]]s and [[scale (zoology)|scales]].<ref>{{cite web |url = http://trianglek.org/kosherdefined.html |title = Kosher defined |access-date = 1 December 2010 |publisher = [[Triangle K]] }}</ref> They are therefore not eaten by observant [[Jew]]s, and some Christian denominations.<ref name="Meyer-Rochow 2009">{{cite journal |last = Meyer-Rochow |first = Victor Benno |title = Food taboos: their origins and purposes |journal = Journal of Ethnobiology and Ethnomedicine |date = 2009 |volume = 5–18 |page = 18 |doi = 10.1186/1746-4269-5-18 |pmid = 19563636 |pmc = 2711054 |doi-access = free }}</ref><ref>{{Cite web |title=Kashrut |url=https://www.ourrabbis.org/main/halakhah-mainmenu-26/kashrut-mainmenu-34 |access-date=2025-02-08 |website=www.ourrabbis.org}}</ref>

=== Bait ===

Crayfish are preyed upon by a variety of [[ray-finned fish]]es,<ref name="Web 2002">{{cite web |last = Web |first = Animal Diversity |title = Kids' Inquiry of Diverse Species, Orconectes propinquus, northern clearwater crayfish: INFORMATION |website = BioKIDS |date = 16 September 2002 |url = http://www.biokids.umich.edu/critters/Orconectes_propinquus/ |access-date = 27 July 2018 }}</ref> and are commonly used as [[fishing bait|bait]], either live or with only the tail meat. They are a popular bait for catching [[catfish]],<ref>{{cite web |last = Samsel |first = Jeff |title = 5 Great Catfish Baits |website = Game & Fish |date = 5 August 2005 |url = https://www.gameandfishmag.com/editorial/5-great-catfish-baits/245174 |access-date = 13 February 2021 |archive-date = 8 November 2021 |archive-url = https://web.archive.org/web/20211108152833/https://www.gameandfishmag.com/editorial/5-great-catfish-baits/245174 }}</ref> [[largemouth bass]], [[smallmouth bass]], [[striped bass]],<ref name="Bass Fishing Gurus 2015">{{cite web |title = Striped Bass Feeding Facts and Information |website = Bass Fishing Gurus |date = 4 March 2015 |url = https://bassfishing-gurus.com/striped-bass-feeding-facts-and-information/ |access-date = 27 July 2018 }}</ref> [[perch]], [[Northern pike|pike]]<ref name="Funny Fishing Tshirts & Fishing Gifts - Fish Face 2017">{{cite web |title = The Key to Locating Bass, Walleye or Pike |website = Funny Fishing Tshirts & Fishing Gifts – Fish Face |date = 25 August 2017 |url = https://www.fishface.com/-fishing-hunting-outdoor-blog/locating-bass-walleye-pike-with-crayfish |access-date = 27 July 2018 |archive-url = https://web.archive.org/web/20180727212242/https://www.fishface.com/-fishing-hunting-outdoor-blog/locating-bass-walleye-pike-with-crayfish |archive-date = 27 July 2018 }}</ref> and [[muskellunge|muskie]]. When using live crayfish as bait, anglers prefer to hook them between the eyes, piercing through their hard, pointed beak which causes them no harm; therefore, they remain more active.<ref name="Bean 2011">{{cite web |last = Bean |first = Richard Alden |title = Crayfish: What Better Spring Bait For Bass? |website = Game & Fish |date = 6 April 2011 |url = http://www.gameandfishmag.com/fishing/fishing_bass-fishing_crayfish_what_better_spring_bait0411/ |access-date = 27 July 2018 }}</ref>

When using crayfish as bait, it is important to fish in the same environment where they were caught. An [[Illinois State University]] report that focused on studies conducted on the [[Fox River (Illinois River tributary)|Fox River]] and [[Des Plaines River]] watershed stated that [[rusty crayfish]], initially caught as bait in a different environment, were dumped into the water and "outcompeted the native clearwater crayfish".<ref>{{cite book |chapter-url = http://dnr.state.il.us/orep/ctap2/Chp%205.pdf |chapter = Fox and Des Plaines Rivers Watershed |title = Critical Trends in Illinois Ecosystems |publisher = [[Illinois Department of Natural Resources]] |year = 2001 |access-date = 10 February 2009 |archive-date = 27 March 2009 |archive-url = https://web.archive.org/web/20090327041058/http://dnr.state.il.us/orep/ctap2/Chp%205.pdf }}</ref> Other studies confirmed that transporting crayfish to different environments has led to various ecological problems, including the elimination of native species.<ref>{{cite book |url = http://www.state.tn.us/twra/pdfs/aquaticplan.pdf |archive-url = https://web.archive.org/web/20080909204843/http://www.state.tn.us/twra/pdfs/aquaticplan.pdf |archive-date = 9 September 2008 |url-status = live |title = Tennessee Aquatic Nuisance Species Management Plan |author = Tennessee Aquatic Nuisance Species Task Force |year = 2007 |publisher = [[Tennessee Wildlife Resources Agency]] }}</ref> Transporting crayfish as live bait has also contributed to the spread of [[zebra mussels]] in various waterways throughout Europe and North America, as they are known to attach themselves to exoskeleton of crayfishes.<ref name=HaGov>{{cite web |title = Hawaii Risk Analyses and Management for Dreissenid Mussels |url = https://dlnr.hawaii.gov/ais/files/2014/02/Hawaii-Dreissena-Mussel-Assessment-2012.pdf |archive-url = https://web.archive.org/web/20141030053210/http://dlnr.hawaii.gov/ais/files/2014/02/Hawaii-Dreissena-Mussel-Assessment-2012.pdf |archive-date = 30 October 2014 |url-status = live |page = 3 |publisher = US Fish & Wildlife |date = 2012 |access-date = 27 July 2018 }}</ref><ref name="Nonindigenous Aquatic Species 2005">{{cite web |title = zebra mussel (Dreissena polymorpha) – Species Profile |website = Nonindigenous Aquatic Species |date = 16 November 2005 |url = https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=5 |access-date = 27 July 2018 }}</ref><ref>{{cite web |url = https://sfbay.wr.usgs.gov/benthic_eco/exotic_species/next.html |title = The History and Effects of Exotic Species in San Francisco Bay |author1 = J. Thompson |author2 = F. Parchaso |author3 = A. Alpine |author4 = J. Cloern |author5 = B. Cole |author6 = O. Mace |author7 = J. Edmunds |author8 = J. Baylosis |author9 = S. Luoma |author10=F. Nichols |publisher = [[United States Geological Survey]] |date = 13 December 2007 |access-date = 10 February 2009 |archive-date = 1 July 2013 |archive-url = https://web.archive.org/web/20130701135651/http://sfbay.wr.usgs.gov/benthic_eco/exotic_species/next.html }}</ref>

=== Pets ===

Crayfish are kept as pets in freshwater aquariums. They prefer foods like shrimp pellets or various vegetables, but will also eat tropical fish food, regular fish food, algae wafers, and small fish that can be captured with their claws. A report by the [[National Park Service]]<ref name="abebault">{{cite web |author = abebault |website = Google |url = https://www.nps.gov/laro/learn/education/upload/Crayfish-facts.docx |archive-url = https://web.archive.org/web/20170216180121/https://www.nps.gov/laro/learn/education/upload/Crayfish-facts.docx |archive-date = 16 February 2017 |title = Crayfish Facts |date = May 2013 |access-date = 27 July 2018 }}</ref> as well as video and anecdotal reports by aquarium owners<ref name="YouTube 2018">{{cite web |title = YouTube |website = YouTube |date = 12 April 2018 |url = https://www.youtube.com/watch?v=kliDZyD5KnU |archive-url = https://ghostarchive.org/varchive/youtube/20211030/kliDZyD5KnU |archive-date = 30 October 2021 |access-date = 27 July 2018 }}{{cbignore}}</ref> indicate that crayfish will eat their moulted exoskeleton "to recover the calcium and phosphates contained in it."<ref name="abebault"/>  As omnivores, crayfish will eat almost anything; therefore, they may explore the edibility of aquarium plants in a fish tank. However, most species of dwarf crayfish, such as ''[[Cambarellus patzcuarensis]]'', will not destructively dig or eat live aquarium plants.<ref name = petshrimp>{{cite web |author = Gerald Pottern |title = Mexican dwarf orange crayfish, ''Cambarellus patzcuarensis'' |url = http://www.petshrimp.com/articles/cpatzcuarensis.php |access-date = 13 October 2010 |archive-date = 28 July 2018 |archive-url = https://web.archive.org/web/20180728223247/http://www.petshrimp.com/articles/cpatzcuarensis.php }}</ref>

In some nations, such as the [[United Kingdom]], [[United States]], [[Australia]], and [[New Zealand]], imported alien crayfish are a danger to local rivers. The three most widespread American species invasive in Europe are ''[[Faxonius limosus]]'', ''[[Pacifastacus leniusculus]]'' and ''[[Procambarus clarkii]]''.<ref name="lee-james">{{cite web |author = James R. Lee |title = TED Case Studies Crayfish Plague #478 European Crayfish Dispute |date = 5 December 1998 |url = http://www.american.edu/TED/crayfish.htm |archive-url = https://web.archive.org/web/20090110015542/http://www.american.edu/TED/crayfish.htm |archive-date = 10 January 2009 |access-date = 20 January 2008 }}</ref> Crayfish may spread into different bodies of water because specimens captured for pets in one river are often released into a different catchment. There is a potential for ecological damage when crayfish are introduced into non-native bodies of water: e.g., [[crayfish plague]] in Europe, or the introduction of the common yabby (''Cherax destructor'') into drainages east of the Great Dividing Range in Australia.<ref name=auzoo>{{cite journal |author1 = Coughran, J |author2 = Mccormack, R |author3 = Daly, G |title = Translocation of the Yabby ''Cherax destructor'' into eastern drainages of New South Wales, Australia |journal = Australian Zoologist |volume = 35 |year = 2009 |pages = 100–103 |doi = 10.7882/AZ.2009.009 |url = https://www.researchgate.net/publication/271520252 |access-date = 10 May 2018 }}</ref>

=== Education ===
Some [[Education in the United States|public schools]] in the United States keep live crayfish in the classroom and have the students take care of them in order to give the students a greater understanding of the creatures.<ref>{{Cite web |date=2011-06-01 |title=Crayfish give fourth graders a "pinch" of science education |url=https://www.castlepinesconnection.com/crayfish-give-fourth-graders-a-pinch-of-science-education/ |access-date=2024-06-13 |website=The Castle Pines Connection |language=en-US}}</ref>

=== Sentinel species ===

The Protivin brewery in the [[Czech Republic]] uses crayfish outfitted with sensors to detect any changes in their bodies or pulse activity in order to monitor the purity of the water used in their product. The creatures are kept in a fish tank that is fed with the same local natural source water used in their brewing. If three or more of the crayfish have changes to their pulses, employees know there is a change in the water and examine the parameters.<ref name="Brewery">{{cite news |url = https://www.reuters.com/article/us-czech-crayfish-water-purity/crayfish-staff-help-czech-brewery-keep-its-water-as-pure-as-can-be-idUSKCN1C22GP |archive-url = https://web.archive.org/web/20191025221438/https://www.reuters.com/article/us-czech-crayfish-water-purity/crayfish-staff-help-czech-brewery-keep-its-water-as-pure-as-can-be-idUSKCN1C22GP |title = Crayfish staff help Czech brewery keep its water as pure as can be |work = [[Reuters TV]] |last = Hanrahan |first = Mark |date = 27 September 2017 |archive-date = 25 October 2019 |access-date = 25 October 2019 }}</ref>

Scientists also monitor crayfish in the wild in natural bodies of water to study the levels of pollutants there. This use makes crayfish an [[indicator species]].<ref name="Brewery" /><ref name="Missouri">{{cite magazine |url = https://mdc.mo.gov/conmag/2008/11/clean-water |title = Clean Water |magazine = Missouri Conservationist Magazine |publisher = Missouri Department of Conservation |date = November 2008 |volume = 69 |issue = 11 |access-date = 25 October 2019 |archive-date = 25 October 2019 |archive-url = https://web.archive.org/web/20191025224345/https://mdc.mo.gov/conmag/2008/11/clean-water }}</ref><ref name="Meuse">{{Cite journal |first1 = P. A. E. L. |last1 = Schilderman |first2 = E. J. C. |last2 = Moonen |first3 = L. M. |last3 = Maas |first4 = I. |last4 = Welle |first5 = J. C. S. |last5 = Kleinjans |year = 1999 |title = Use of Crayfish in Biomonitoring Studies of Environmental Pollution of the River Meuse |journal = Ecotoxicology and Environmental Safety |volume = 44 |issue = 3 |pages = 241–252 |doi = 10.1006/eesa.1999.1827 |pmid = 10581118 |bibcode = 1999EcoES..44..241S |issn = 0147-6513 }}</ref>

== See also ==
{{portal|Crustaceans}}
* [[Arthropods in culture]]
* [[Pain in crustaceans]]

== Notes ==
{{notelist}}

== References ==
{{reflist}}

== Further reading ==
{{refbegin}}
* {{cite journal |author1 = Christoph Goessmann |author2 = Charlotte Hemelrijk |author3 = Robert Huber |year = 2000 |title = The formation and maintenance of crayfish hierarchies: behavioral and self-structuring properties |journal = [[Behavioral Ecology and Sociobiology]] |volume = 48 |issue = 6 |pages = 418–428 |doi = 10.1007/s002650000222 |bibcode = 2000BEcoS..48..418G |s2cid = 9288247 |url = http://caspar.bgsu.edu/~lobsterman/Page/Papers/2000GoeHemHub.pdf |archive-url = https://web.archive.org/web/20060907094151/http://caspar.bgsu.edu/%7elobsterman/Page/Papers/2000GoeHemHub.pdf |archive-date = 7 September 2006 |url-status = live }}
* {{cite book |author = Thomas Henry Huxley |author-link = Thomas Henry Huxley |year = 1880 |title = The Crayfish: an Introduction to the Study of Zoology |publisher = D. Appleton & Co. |location = New York |url = https://archive.org/details/crayfishintroduc00huxl }}
* {{cite book |author1 = Sterling K. Johnson |author2 = Nathan K. Johnson |year = 2008 |title = Texas Crawdads |location = College Station, Texas |isbn = 978-0-9801103-0-2 |publisher = Crawdad Club Designs }}
* [http://www.kmae-journal.org/articles/kmae/abs/2009/03/contents/contents.html Regional European Crayfish Workshop: Future of Native Crayfish in Europe]. ''[[Knowledge and Management of Aquatic Ecosystems]]''. No. 394–395 (2009).
* {{cite book |author = Jerry G. Walls |title = Crawfishes of Louisiana |location = Baton Rouge, LA |publisher = Florida State University Press |year = 2009 |isbn = 978-0-8071-3409-2 }}
{{refend}}

== External links ==
{{Commons and cat}}
* [https://web.archive.org/web/20090719152229/http://iz.carnegiemnh.org/crayfish/iaa/index.htm International Association of Astacology (IAA)]
* [https://www.youtube.com/watch?v=MuuIlZyrySE&spfreload=10 America's Crayfish: Crawling In Troubled Waters]
* [https://web.archive.org/web/20200416172558/https://crawfish.org/ Louisiana Crawfish Research and Promotion Board]
* {{YouTube|mF6NgMBcNCM|Crayfish Moulting Video}}
* [https://web.archive.org/web/20240126195303/https://ontarionature.org/wp-content/uploads/2017/10/crayfish_apr08.pdf Species of Ontario Crayfish]

{{Decapoda}}
{{Edible crustaceans}}
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[[Category:Crayfish| ]]
[[Category:Freshwater crustaceans]]
[[Category:Mesozoic first appearances]]
[[Category:Articles containing video clips]]
[[Category:Arthropod common names]]