{{Short description|Large species of freshwater crayfish which is native to the United States}} {{Speciesbox | image = Rusty Crayfish (Faxonius rusticus) - Guelph, Ontario 2020-04-08 (06).jpg | image_alt = | image_caption = Rusty crayfish (''Faxonius rusticus'') in Guelph, Ontario, Canada | image2 = Faxonius rusticus-male dorsal.jpg | image2_caption = Rusty spots on sides of carapace | status = LC | status_system = IUCN3.1 | status_ref = {{r|iucn}} | status2 = G5 | status2_system = TNC | status2_ref = <ref>{{cite NatureServe |id=2.117283 |title=''Faxonius rusticus'' |access-date=27 January 2025}}</ref> | genus = Faxonius | species = rusticus | authority = (Girard, 1852) | synonyms = {{Species list | Cambarus rusticus | Girard, 1852 | Orconectes rusticus | (Girard, 1852) }} | synonyms_ref = {{r|crandall2017}}<ref>{{GBIF |id=8979506 |taxon=Faxonius rusticus |accessdate=2022-03-24}}</ref> }}
The '''rusty crayfish''' ('''''Faxonius rusticus''''') is a large, aggressive species of freshwater crayfish which is native to the United States, in the Ohio River Basin in parts of Ohio, Kentucky, and Indiana.{{r|crandall2017}}{{r|gisd}}{{r|invspinfo}} Its range is rapidly expanding across much of eastern North America, displacing native crayfishes in the process.<ref name="Gunderson, 2001">Gunderson, Jeffrey (2000). [http://www.nicerweb.com/sketches/crayfish/rusty/rusty_sex.html "Rusty Crayfish Gender Identification."] Minnesota Sea Grant. Retrieved 3 November 2025.</ref>{{r|invading}} The rusty crayfish was first captured in Illinois in 1973, and has been collected at over 20 locations in the northern portion of the state.{{r|taylor1996}} In 2005, ''F. rusticus'' was found for the first time west of the Continental Divide, in the John Day River, Oregon, which runs into the Columbia River.{{r|olden2009}}
==Description== thumb|Measurement of a rusty crayfish Adult rusty crayfish can reach 10 centimeters (4 inches) in length, although they reach maturity at about 4.4 cm (1.7 in),<ref name="Pappas, J. 2002">Pappas, Janice (2002). [http://animaldiversity.org/accounts/Orconectes_rusticus/ ''Orconectes rusticus'']. Mulcrone, R. S. (ed.). Animal Diversity Web. Retrieved 3 November 2025.</ref> and can range in color from greenish grey, to reddish brown,<ref name="Bovbjerg 1952">{{cite journal|author=Bovbjerg, Richard V. |title=Comparative Ecology and Physiology of the Crayfish, ''Orconectes propinquus'' and ''Cambarus fodiens'' |jstor=30160911|journal=Physiological Zoology|volume=25|issue=1 |year=1952|pages=34–56 |doi=10.1086/physzool.25.1.30160911 |s2cid=87913861 }}</ref><ref name="Pintor 2009">{{cite journal|doi=10.1007/s10530-008-9367-2|author1=Pintor, Lauren M.|author2=Sih, Andrew|title=Differences in Growth and Foraging Behavior of Native and Introduced Populations of an Invasive Crayfish|journal=Biological Invasions |volume=11 |issue=8 |pages=1895–1902 |year=2008 |s2cid=19550240 }}</ref><ref name="Rabalais 2006">{{cite journal|author1=Rabalais, M. R.|author2=Magoulick, D. D.|title=Influence of an Invasive Crayfish Species on Diurnal Habitat Use and Selection by a Native Crayfish Species in an Ozark Stream|journal=The American Midland Naturalist|volume=155|issue=2|pages=295–306|jstor=4094645|doi=10.1674/0003-0031(2006)155[295:IOAICS]2.0.CO;2|year=2006|s2cid=85898164 }}</ref> They can be recognized by two "rusty", reddish colored spots variably present<ref name=phillips2010>{{cite web|url=https://waves-vagues.dfo-mpo.gc.ca/library-bibliotheque/340724.pdf|title=Biological Synopsis of the Rusty Crayfish (''Orconectes rusticus'')|author=Phillips, I. D.|year=2010|series=Canadian Manuscript Report of Fisheries and Aquatic Sciences 2923|publisher=Fisheries and Oceans Canada|access-date=3 November 2025|pages=2-3}}</ref> on the sides of their posterior carapace<ref name="Pappas, J. 2002"/> and their large front claws with black bands around the tips.<ref name="Minnesota Sea Grant">Jensen, Doug (26 July 2013). [http://www.seagrant.umn.edu/ais/rustycrayfish#id "Rusty Crayfish"]. Minnesota Sea Grant. {{webarchive|url=https://web.archive.org/web/20200226005830/https://seagrant.umn.edu/ais/rustycrayfish#id|date=26 February 2020}}</ref> Male astacoid crayfish have small hook-like features, or copulatory stylets,<ref>{{citation|last=Crocker|first=Denton W.|title=The Crayfishes of New York State (Decapoda, Astacidae)|series=New York State Museum and Science Service Bulletin Number 355|publisher=The University of the State of New York|date=May 1957|location=Albany|url=https://decapoda.nhm.org/pdfs/32071/32071-001.pdf|access-date=3 November 2025|pages=13-14}}</ref> that are used to hold onto a female while mating,<ref name="Gunderson, 2001"/> prominent in rusty crayfish on the ischia of the third pair of pereopods for those males in their form I (reproductive) molt.<ref name="Gunderson, 2001"/><ref name=phillips2010/>
<gallery mode="packed"> File:Faxonius rusticus-male ventral.jpg|Male in Illinois </gallery>
==Behavior== thumb|Two adult male rusty crayfish fighting for dominance. Many species of vertebrates that live in communities together utilize a dominance hierarchy to establish order, and studies have shown that some species of invertebrates do as well.<ref name="Alexander 1961">{{cite journal|author=Alexander, R. D.|title=Aggressiveness, territoriality, and sexual behavior in field crickets (Orthoptera: Gryllidae)|journal=Behaviour|volume=17|issue=2|pages=130–223|jstor=4532972|doi=10.1163/156853961X00042|year=1961}}</ref><ref name="Courchesne & Barlow 1971">{{cite journal|author1=Courchesne, E.|author2=Barlow, G. W.|title=Effect of isolation on components of aggressive and other behavior in the hermit crab, ''Pagurus samuelis''|journal=Zeitschrift für Vergleichende Physiologie|volume=75|pages=32–48|doi=10.1007/BF00335136|year=1971|s2cid=13459037 }}</ref> The dominance hierarchy is an important aspect of a crayfish's biology and behavior. Crayfish tend to form dominance hierarchies with the other members of their population in a particular environment. The largest male will generally demonstrate the most dominance over the others by being the most aggressive, and picking fights with the other, smaller crayfish. The crayfish that wins the most fights is placed at the top of the hierarchy with the other members generally ranking in descending order based on size and sex.<ref name="Copp, 1986 ">{{cite journal|author=Copp, Newton H. |title=Dominance Hierarchies in the Crayfish ''Procambarus clarkii'' (Girard, 1852) and the Question of Learned Individual Recognition (Decapoda, Astacidea)|journal=Crustaceana|volume=51|issue=1|pages=9–24|jstor=20104160|doi=10.1163/156854086X00025|year=1986 |bibcode=1986Crust..51....9C }}</ref> Studies have suggested that the largest determining factor in the formation of dominance hierarchies is size rather than sex. That means that female rusty crayfish can rank higher in the dominance hierarchy than male rusty crayfish if they are larger than them.<ref name="Copp, 1986 "/>
==As an invasive species== The larger size and aggressive nature of rusty crayfish that have been introduced to a body of water makes it harder for them to be preyed upon by native species of fish, which are not accustomed to crayfish fighting them back.<ref name="Hein, 2006">{{cite journal|title=Fish Predation and Trapping for Rusty Crayfish (''Orconectes rusticus'') Control: A Whole-lake Experiment|journal=Canadian Journal of Fisheries and Aquatic Sciences|volume=63|issue=2|page=383|doi=10.1139/f05-229|year=2006|last1=Hein|first1=Catherine L|last2=Roth|first2=Brian M|last3=Ives|first3=Anthony R|last4=Zanden|first4=M Jake Vander |bibcode=2006CJFAS..63..383H }}</ref> Instead of running away like the native crayfish species do when they come in contact with a predator, the rusty crayfish will take an attack stance with its claws raised above its head, which will generally scare away most predatory fish. Additionally, adult rusty crayfish can be too large for some fish to consume.<ref name="Wisconsin Aquatic Invasive Species, 2008">[http://limnology.wisc.edu/personnel/jakevz/ais/rustycrayfish.html "Wisconsin Aquatic Invasive Species."] wisc.edu</ref> Because the rusty crayfish are able to avoid predators fairly well, their population in these new aquatic ecosystems was able to grow extremely quickly and within twenty years the rusty crayfish population had exploded and become an invasive species in the Northern United States and parts of Canada.<ref name="Olden et. all, 2006">{{cite journal|doi=10.1007/s10530-005-7854-2|title=The rapid spread of rusty crayfish (''Orconectes rusticus'') with observations on native crayfish declines in Wisconsin (U.S.A.) over the past 130 years|journal=Biological Invasions|volume=8|issue=8|page=1621|year=2006|last1=Olden|first1=Julian D.|last2=McCarthy|first2=Julia M.|last3=Maxted|first3=Jeffrey T.|last4=Fetzer|first4=William W.|last5=Vander Zanden|first5=M. Jake|bibcode=2006BiInv...8.1621O |citeseerx=10.1.1.546.4281|s2cid=11304533 }}</ref> Because these rusty crayfish populations have basically taken over the natives species' habitats and forced them out of their homes, many populations of native crayfish have experienced drastic decline over the past fifty years and the rusty crayfish has become the dominant species in much of the Midwestern United States.<ref name="Pintor 2009"/>
===Control efforts=== While chemicals that kill crayfish exist, none are specific to rusty crayfish.<ref name="in.gov">[http://www.in.gov/dnr/files/RUSTY_CRAYFISH.pdf "Rusty Crayfish."] in.gov. {{webarchive|url=https://web.archive.org/web/20190610170515/http://www.in.gov/dnr/files/RUSTY_CRAYFISH.pdf|date=10 June 2019}}</ref> Harvesting for consumption is expected to solely impact the adult population.<ref name="in.gov"/> Once a population of rusty crayfish is introduced to a body of water, it may be very difficult to completely eradicate them. Therefore, the best control strategy is to try to prevent any further spread of the rusty crayfish. The best methods to prevent spread of invasive species are to learn to identify them, and to avoid using invasive species as bait or to otherwise transport them to bodies of water where they are not already present.<ref name="Minnesota Sea Grant"/>
In the European Union, it is included in the list of invasive alien species of Union concern and hence cannot be imported, bred, transported, commercialized, or intentionally released into the environment in any of its member states.<ref>{{Cite web |title=List of Invasive Alien Species of Union concern |url=https://eur-lex.europa.eu/legal-content/EN/TXT/HTML/?uri=CELEX:02016R1141-20250807 |date=7 August 2025 |access-date=8 May 2026|website=eur-lex.europa.eu}}</ref><ref>{{Cite web |title=Regulation No. 1143/2014 of the European parliament and of the council of 22 October 2014 on the prevention and management of the introduction and spread of invasive alien species |url=https://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32014R1143&from=EN |publisher=European Union |date=2014-11-04 |location=Strasbourg |access-date=2026-05-08 |archive-date=2017-03-03 |archive-url=https://web.archive.org/web/20170303185733/http://eur-lex.europa.eu/legal-content/EN/TXT/PDF/?uri=CELEX:32014R1143&from=EN |url-status=live }}</ref>
==References== {{Reflist|refs= <ref name=crandall2017>{{cite journal|author-link1=Keith A. Crandall |last1=Crandall |first1=Keith |last2=De Grave |first2=Sammy |title=An updated classification of the freshwater crayfishes (Decapoda: Astacidea) of the world, with a complete species list |journal=Journal of Crustacean Biology |date=2017 |volume=37 |issue=5 |pages=615–653 |doi=10.1093/jcbiol/rux070|doi-access=free }}</ref> <ref name=gisd>[http://www.iucngisd.org/gisd/species.php?sc=217 Global Invasive Species Database]</ref> <ref name=invading>[http://www.invadingspecies.com/rusty-crayfish/ www.invadingspecies.com] Partnership between the Ontario Ministry of Natural Resources and the Ontario Federation of Anglers and Hunters</ref> <ref name=invspinfo>[https://www.invasivespeciesinfo.gov/profile/rusty-crayfish Species Profile - Rusty Crayfish (''Orconectes rusticus'')], National Invasive Species Information Center, United States National Agricultural Library</ref> <ref name=iucn>{{Cite iucn |author=S. Adams |author2=G. A. Schuster |author3=C. A. Taylor |name-list-style=amp |title=''Orconectes rusticus'' |volume=2010 |article-number=e.T153835A4551760 |date=2010 |doi=10.2305/IUCN.UK.2010-3.RLTS.T153835A4551760.en|access-date=15 September 2023}}</ref> <ref name=olden2009>{{cite journal|author1=Olden, Julian D.|author2=Adams, Jeffrey W.|author3=Larson, Eric R.|name-list-style=amp|year=2009|title=First record of ''Orconectes rusticus'' (Girard, 1852) (Decapoda, Cambaridae) west of the Great Continental Divide in North America |journal=Crustaceana |volume=82 |issue=10 |pages=1347–1351 |doi=10.1163/156854009X448934 |bibcode=2009Crust..82.1347O |url=http://www.fish.washington.edu/research/oldenlab/pdf/2009/Crustaceana_2009.pdf |archive-url=https://web.archive.org/web/20100702084044/http://fish.washington.edu/research/oldenlab/pdf/2009/Crustaceana_2009.pdf |archive-date=2010-07-02 }}</ref> <ref name=taylor1996>{{cite journal |last1=Taylor |first1=Christopher A. |last2=Redmer |first2=Michael |title=Dispersal of the Crayfish ''Orconectes rusticus'' in Illinois, with Notes on Species Displacement and Habitat Preference |journal=Journal of Crustacean Biology |date=1996 |volume=16 |issue=3 |pages=547–551 |doi=10.2307/1548745 |jstor=1548745 |bibcode=1996JCBio..16..547T |issn=0278-0372}}</ref> }}
{{Taxonbar|from1=Q59712751|from2=Q3933598}}
Category:Cambaridae Category:Freshwater crustaceans of North America Category:Crustaceans described in 1852 Category:Endemic crustaceans of the United States Category:Taxobox binomials not recognized by IUCN Category:Least concern biota of the United States Category:Taxa named by Charles Frédéric Girard <!-- Faxonius rusticus -->