A Field-Guide to the Crayfishes of

Obed Wild and Scenic River By Roger F. Thoma

Contents EmoryRivercrayfish............... 22Introduction.................................................. 1 Tanbackcrayfish.................24Howtoidentifyacrayfish............................ 3 Valleyflamecrayfish...........26ObedEmoryRivercrayfishkey................... 6 Triangleclawcrayfish..........28Species.accounts........................................ 10 Ambiguouscrayfish.............30 Thornytailcrayfish......................... 10 Bigclawcrayfish..................32 Uplandburrowingcrayfish............ 12 Rustycrayfish......................34 Mountainmidgetcrayfish.............. 14. . Literature.........................................36 Boxclawcrayfish........................... 16

Hairyfootcrayfish.......................... 18

ObedRivercrayfish........................ 20

Introduction:TheObedNationalWildandScenicRiv-erNationalPark,locatedontheCumberlandPlateauofTennessee,hasthirteenspeciesofcrayfishlivingwithinornearitsboarders.Thesethirteenspeciescomefromtwogenera in the familyCambaridae, a solelyNorthAmerican crayfish family. There are currently sevenfamiliesofcrayfishworldwide.

The two Obed genera are highly specious (approxi-mately 100 species each) and widespread. They areCambarus.and.Orconectes. In total thereareapproxi-mately360speciesofcrayfishintheUnitedStatesandCanada.and.approximately.80.species.are.known.to.oc-cur.in.Tennessee.

IntheObedareacrayfishcanbefoundinanysurfacewaterareaandmostareaswherethewatertableisclosetothesurface.ThreeofthespeciesfoundintheObedareaareburrowersthatspendalmostalloftheirlivesinburrows.and.are.rarely.found.out.in.open.water..Cray-fish display three basic life strategies; living in openwaterandhidingunderobjectssuchaswoodydebris

androcks,livinginshortburrowsdugintostreambanksor under large rocks, and burrowing vertically intogroundwaterthatisfoundnearthesurface.Technicalterminologyfortheselifestylesistertiary,secondary,and.primary.burrowers.respectively.

ThegeneralizedpatternofreproductioninNorthAmer-ican crayfish is normally tomate in late fall or earlyspring,layingofeggsfromearlyspringtoearlysum-mer anddispersal of young inmid summer.Crayfishmatingisreferredtoasamplexus.Femalecrayfishcarryaspermplugwiththemintheirannulusventralisuntiltheylaytheireggs.Theeggsareconsequentlycarriedby the femaleonherpleopodsasare theyounguntiltheyareoldenoughtodisperse.

Thelifespanofcrayfishcanvarybasedonthetypeofhabitataspeciesoccupies.Speciesthatliveinwarmerwatersseemtoliveforaboutthreetofouryears.Thosethatliveincolderwaterssuchassprings,burrows,andcavescanlivefromsixtotwentyplusyears.Muchworkneedstobedonewithcrayfishlifehistoriesbefore

asolidunderstandingofthecrayfish’sroleinoureco-systems.can.be.fully.understood..It.is.generally.under-stoodthatcrayfishformanimportantfactorinaquaticecosystems.processing.large.portions.of.a.systems.energy.and.biomass.as.well.as.altering.and.creating.habitat.Over260animalspeciesareknowntofeedoncrayfish.Crayfishareknowntofeedateverylevelofthefoodchain.

Specialnote:AlllinedrawingsusedinthisdocumentarederivedfromHobbs,Jr.1989,TaylorandSchuster2004.or.self.drawn.

Maps:Themapsprovidedinthisfieldguidearefo-cusedontheObedEmoryRiverarea.Themaponthispagedisplaysthedrainagebasin’sstreams,collectionsites,andthethreeecoregionsinthearea.Bluerepris-entstheSouthwesternAppalachians,greentheCentralAppalachians,andyellowtheCentralAppalachianRidgeandValleysEcoregions.Streamsareeithergreen,bluefortheEmoryRivermainsten,orredfortheObedRivermainstem.Crayfishcollectionsitesare

denotedwithblackdots.Eachcountyislabeled.

Figures:IneachspeciesaccountisalinedrawingillustrationderivedfromHobbs,Jr.1989.Forthegenera.Cambarus.and.Orconectesfromlefttorightarefiguredadorsalviewofthecarapace,innerviewfirstformmalegonopod,outerviewfirstformmalegono-pod,outerviewsecondformmalegonopod,annulusventralisoffemale,anddorsalviewofchelae1.

How to identify crayfish:ThefigureabovegivesageneralizedoutlineofthebodystructureofaNorthAmericancrayfish.ThemostimportantbodypartsfortheidentificationofObedcrayfishonthisfigurearetherostrum(betweentheeyes),cervicalspine(onthesideofthebody),areolaanditswidth(dorsalmidbody),andthechelae’spropodus,dactylandpalm.

Therostrumwilleitherhaveornothavemarginal(lateral)spines,thebodywilleitherhaveornothavecervicalspines,andthewidthoftheareolawillbewideornarrow.Notfiguredisthetuberculationofthedorsalchelaepalm.Palmertuberclescanbeinrowsorgenerallyscatteredabout.Therecanbeseveralrowsoronly.one.row.of.tubercles.and.some.rows.can.be.com-plete(runthelengthofthepalm)whileothersarein-complete.Alsonotillustratedarethetuberclesontheinnermarginsofthechelaefingers.OfspecialuseintheObedareaisthepresenceofdenticlsontheinnermarginsofthechelaefingers.Denticlesareverysmallspinelikestructuresthatlookliketinyteeth.Agroupofthreespecieshavethesesmalldenticlesrunningthefulllengthofthefingerswiththedenticlesappearingbetweenthelargertubercles.Intheotherspeciesthedenticlesdonotrunpastthemidpointofthefingerandarefoundnearthetipsordistalends.

CrayfishinNorthAmericagothroughreproductiveseasonsorcycles.Associatedwithreproduction,malecrayfishdisplayaspecialreproductiveformreferredto

as“firstform”.Whennotinreproductiveformamaleiscalledsecondform.Associatedwitheachspeciesaccountisalinedrawingshowingtheshapeofthefirstformandsecondformmalegonopod.Onemustlearntodistinguishbetweenthetwopossibleformstobeabletodistinguishanytwospeciesinquestion.Thefirstformmalegonopodisalwaysmoredelicatelysculpturedandpartofthetipwillbeadarkerbrowncolorandisdescribedascorneous(consistingofahornysubstance).Thefigurestotherightshowafirstformmale(left)andasecondformmale(right)gono-podforthegeneraOrconectes(left)andCambarus.(right).Thegonopodlocationisillustratedinthegen-eralizedcrayfishdrawing.TheyarelabeledasPleo-podsI.FemalecrayfishlackgonopodsandbetweenPereiopodsV(fifthpairoflegs)isfoundtheannulusventralis.Thisstructureisillustratedintheindividualspecies.accounts.

Whenexaminingthechelaestructureofacrayfishallcharactersareobservedfromthedorsalsurface.Nu-meroustuberclescanbeobservedonthemesialsur-

facebelowthemovablefinger(thedactyl).Thisareaiscalledthepalmandthetuberclesarecalledpalmertubercles.Rowsoftuberclesarenumberedfromthemesialmargininwardasfirstrow,secondrow,etc.Somespeciesdonothavetheirtubercleslinedupinrowsbutscatteredrandomlyacrossthesurface,thoughontheinneredgeofthepalmtuberclescanappeartoform.a.row.

Thechelaehave“fingers”.Thefingersareformedbythedactyl(themovablefinger)andanextensionofthepropodus.Ontheopposablemargins(thepinchingsurface)ofthefingersarealsofoundtubercles.Some

ofthesearelargerthanthosesurrounding.Theloca-tionoftheseenlargedtuberclesonthefingerscanbediagnosticintheidentificationofaspecies.Asdis-cussedpreviously,somespecieshavedenticles(smallspineliketeeth)thatextendthelengthoftheoppos-ablefingermarginswhilesomehavethemhalfwayorlessdownthefingers.

Theareolaisanareaofthebodypositionedbetweenthegillcambersandislocatedonthedorsalsurfaceofthethorax.Lifehistoryhabitsareexpressedinthestateoftheareola.Thewidthoftheareola(spacebetweenthesuturelines)canaidincrayfishspeciesidentification.Speciesinlowoxygenwaterswillhavenarrowareolaswhilethosethatinhabithighoxygenwaterswillhavewideareolas.

Themandible,thelastpairofappendageslocatedatthemouth,canbeanaidinidentification.Therustycrayfish,foundatonesiteinthebasin,hasauniquemandiblethatlacksthenormaltoothedmarginandhasabladelikeedgetoitthatidentifiesthespecies.All

otherspeciesinthebasinhavemandibleswithteethextendingthetotallengthofthemandibleedge.

Obed Emory River basin crayfish key

1a)Rostrumwiththreespinesattip,2lateral(marginal)andonemiddle,carapacewithcervicalspinesonsides(fig.1a).......................................................................................2

1b)Rostrumwithoutlateralspines,onespineattip,nocervicalspines(fig.1b)............ 4

2a)Chelaewithnoticeabletuftofhairsatbaseoflateralfinger(fig.2a). ........................................................................Tanback crayfish (pg. 24)

2b)Notuftofhairsatbaseofchelae’slateralfinger........................................................3

3a)Mandiblewithteethonallofitsedge...............................Bigclaw crayfish (pg. 32)

3b)Mandiblewithbladelikemarginondistaledge...............Rusty crayfish (pg. 34)

4a)Smalltoothlikedenticlesoninnermarginsofchelaefingersextendinglengthoffin-gerandfoundbetweentuberclesnearbaseoffingers....................................................5

4b)Smalltoothlikedenticlesoninnermarginsofchelaefingersextendinghalfwayorlesslengthofinnerfingers..............................................................................................7

5a)Centralprojectionoffirstformmalegonopodwithsubappicalnotch......................6

5b)Centralprojectionoffirstformmalegonopodwithoutsubappicalnotch. .....................................................................Hairyfoot crayfish (pg. 18)

6a)Centralprojectionoffirstformmalegonopodapproximatelyaslongasmessialpro-cess(fig.5a) ..................................................................Obed River crayfish (pg. 20)

6b)Centralprojectionoffirstformmalegonopodapproximatelyhalfaslongasmessialprocess(fig.6a).............................................................. Emory River crayfish (pg. 22)

7a)Areolaclosed,nospacebetweenedgesofgillchambers(fig.7a)............................8

7b)Areolaopen,spaceforoneormorerowsofpunctationsbetweenedgesofgillcham-bers(fig.7b) ................................................................................................................9

8a)Palmofchelaewithtwodistinctrowsoftubercles,colorinlifered(fig.8b). .................................................................Valley flame crayfish (pg. 26)

8b)Palmofchelaewithmanytuberclescoveringinner,dorsal,halfandnotformingdis-tinctrows,colorinlifemainlybrowns(fig.8a)................Thornytail crayfish (pg. 10)

9a)Chelaeofmatureindividualstriangularshaped,usuallywithtworowsofeasilyseentuberclesoninnermargin,notformingafussedridgeatbase(fig.9a)...........................10

9b)Chelaeofmatureindividualsmorerectangularinshape,usuallyonerowoftuberclesoninnerpalm,tuberclesformingafussedridgelikestructureatbase(fig.9b)..............11

10a)Suborbitalangleacute,areolawidewiththreeormorerowsofpunctationsinnarrowestpart(fig.10a)........................................ Triangleclaw crayfish (pg. 28)

10b)Suborbitalangleobsolete,areolanarrowwithoneortworowsofpunctationsinnarrowestpart(fig.10b)......................................Ambiguous crayfish (pg. 30)

11a)Eyessmall,inneredgeofantennalscalestraightatmidpoint(fig.11a). ........................................................ Mountain midget crayfish (pg. 14)

11b)Eyesnotsmall,inneredgeofantennalscalecurved(fig.11b)...............................12

12a)Colorationverybrightinlifehavingabundantredsandblues,areolanarrow,usu-allywithtworowsofpunctations,centralprojectionofgonopodequalinlengthtomesialprocess(fig.12a)..................................................Upland burrowing crayfish (pg. 12)

12b)Colorationbrownorgreentinlife,areolabroad,usuallywithsixormorerowsofpunctations,centralprojectionofgonopoddistinctlyshorterthanmesialprocess(fig.12b) ...................................................................... Boxclaw crayfish (pg. 16)

Thornytail crayfishCambarus (Tubericambarus) acanthura

Identification:Keycharactersareanobliteratedareolathatformsalinedowntheback,numeroustuberclesonthechelaepalmthatdonotformdistinctrows,andtwosmallmedianspinesattheendofthetailthatprojectbeyondthemarginsofthetail.

ThethornytailcrayfishisuniqueintheObedRiverarea.Nootherspe-ciesinthebasinhastwosmallspinesoverhangingthedistalmarginofthetail.Also,nootherspecieshasnumeroustuberclesthatdonotformdistinctrowscoveringthepalmofthechelae.Theuplandburrowingandambiguouscrayfishcanhaveverynarrowareolasthatcaninsomeindividualsbeobliteratedbutbothhaveonlyonedistinctrowandoc-casionallyasecondlessdevelopedrowoftuberclesontheinneredgeofthechelaepalm.

Color:Thecolorofthethornytailcray-fishisdominatedbybrowns,yellows,andgreens.Thecolorofthechelaeisvaried.Thetipsofthe“fingers”areredorreddishorangealongwithtwotuber-clesatthebaseofthemovable“finger”.Theedgesoftherostrumareredoryel-lowishorange.Tuberclesonthechelaeareusuallylightcream.Theheadandbodyarevermiculatedwithbrowns,yel-lows,andgreens.Colorationcanvarywithageandtimesincemolting.Photo by Zac Loughman.

Distribution:ThethornytailcrayfishisfoundinnorthwestGeor-gia,northeastAlabama,andsoutheastTennesseeintheTennessee,Coosa,BlackWarrior,andChattahoocheeRiverbasins.Thepopu-lationdiscoveredintheEmoryRiverbasinisthefurthestnortheverrecorded.Itappearstobeconfinedtothelowgradient,lowreliefareasofthebasin.SpecimenshaveonlybeencollectedintheEmoryRiverupstreamoftheObedRiverandtheCrookedCreekareasbutitislikelyitwillbefoundallthewaytotheconfluencewiththeTennesseeRiver.

Ecology/Life History: Thethornytailcrayfishmatesandlayseggsinthespring.Thespeciesburrowsexclusivelyinwet-landareasaroundstreams,ditches,andwooded.wetlands.and.is.rarely.found.outsideitsburrowexceptinspring.Thebest.populations.seem.to.be.from.areas.ofditchedwetlandsthoughthisislikelyanartifactoftheeaseofcollecting.Foodpreference.is.unknown.but.may.be.similar.tothecloselyrelatedlittlebrownmudbugwhichwaitsatthemouthofitsburrowandattackssmallinvertebratesthatpassby..

Upland burrowing crayfishCambarus (Jugicambarus) dubius

Identification:Keycharactersarearidgelikerowoftuberclesonin-neredgeofchelaepalm,denticalsextendinglessthathalfwaydown“fingers”ofchelae,nolateralspinesonrostrum,narrowareola,lengthofcentralprojectionofthefirstformmalegonopodusuallyequaltoornearequaltomesialprocess,lifecolorsvibrantbluesandreds.

Theuplandburrowingcrayfishissimilartotheboxclawcrayfishandmountainmidgetcrayfish.Theuplandburrowingcrayfishhassmalleyes.Boxclawandmountainmidgetcrayfishbothhavewideareolas.Otherspeciesinthebasineitherhavelateralspinesatthecervicalgrooveand/orrostralmargins,denticlesthatextendthelengthofthechelae“fingers”,ormorethanonewelldevelopedrowoftuberclesonthechelaepalm.

Color:Thecoloroftheuplandburrow-ingcrayfishisdramatic.Thespecimenpicturedhereisaredbodybluelegcolormorph.Numerouscolorvaria-tionsofthisspeciescanbefoundwithinits.range..Some.populations.are.mostly.bluewithsomereds,orblackwithor-angeorred,someareallreddishorange,whilesomearesolidblue,andmanyarevariationsoftheabovecolorthemes.Colorationwithinapopulationcanvarywithageandtimesincemolting. Photo by Zac Loughman.

Distribution:Theuplandburrowingcrayfishisawidelydistrib-utedspeciesintheAppalachianMountains.Itisfoundfromwest-ernPennsylvaniasouththroughWestVirginia,southwestVirginia,easternKentucky,easternTennessee,andnorthwesternNorthCarolina.Thespeciesshowsnospecialassociationwithdrainagesasitisknowntotraveloverlandduringwetspringnights.WithintheObed/Emorybasinitisfoundthroughouttheareawheresuit-ablehabitatcanbefound.Muchofthebasinisdominatedbysandstonewhichlimitssuitablespringsandseeps.

Ecology/Life History: Theuplandbur-rowingcrayfishmatesinspringandfall.Eggproductionoccursinthespringandearlysummer.Thisspeciesburrowsintospringsandseepsonhillsidesandmoun-taintops.Thebestpopulationsarefromareasofextensiveforestcoverthoughlikethepictureabove,atthetypelocality,healthypopulationscanbefoundinfields.Food.preference.appears.to.be.vegetation.andinvertebrateanimals.Numerousbur-rowshavebeenobservedwithleaflitter,mossesandotherplantsstoredinthem.

Mountain midget crayfishCambarus (Jugicambarus) parvoculus

Identification:Keycharactersareridgelikerowoftuberclesonin-neredgeofchelaepalm,denticalsextendinglessthathalfwaydown“fingers”ofchelae,nolateralspinesonrostrum,wideareola,lengthofcentralprojectionofthefirstformmalegonopodequaltomesialprocess,antennalscalestraightedgedoninnermargin.

Themountainmidgetcrayfishissimilartotheboxclawcrayfishanduplandburrowingcrayfish.Theboxclawanduplandburrowingcrayfishhavelargereyesandroundedantennalscalemargins.Otherspeciesinthebasineitherhavelateralspinesatthecervicalgroove,denticlesthatextendthelengthofthechelae“fingers”,ormorethanonewelldevelopedrowoftuberclesonthechelaepalm.

Color:Thecolorofthemountainmidgetcrayfishisusuallybrown.Thespecimenpicturedhereisabluecolorphaseindividual.Normally,thebody,chelae,andabdomenareasolidbrown.Thelegsarealwayssomeshadeofblue.Tuberclesonthechelaefingersarelightercoloredthanthebackgroundandareusuallyayellowishorcreamcolor.Older,un-moltedindividualscanbe.very.dark.to.black.due.to.staining.by.organic.matter.

Distribution:ThemountainmidgetcrayfishisawidelydistributedspeciesontheCumberlandPlateauandcanbefoundinsoutheast-ernKentuckyintheCumberlandbasin,easternTennesseeintheTennesseeandCumberlandRiverbasins,andthenortherncornersofGeorgiaandAlabamaintheSandMountainareaoftheTennes-seebasin.WithintheObed/Emorybasinitisfoundthroughoutthearea.

Ecology/Life History: Themountainmidgetcrayfishappearstomatefromspringtofall.Eggproductionoccursinthespring.Thisspecieslivesinsmallsizedstreamsandspringswithrockysubstrateswheretheyburrowunderaquaticmosscoveredrocksandintorockybanks.Thebestpopulationsarefromstreamswithanextensiveforestcover,especiallythosedominatedbyhemlockandrhododendron.Food.preferences.as.well.as.life.span.are.unknown.

Boxclaw crayfishCambarus (Jugicambarus) distans

Identification:Keycharactersarearidgelikerowoftuberclesonin-neredgeofchelaepalm,denticalsextendinglessthathalfwaydown“fingers”ofchelae,nolateralspinesonrostrum,wideareola,lengthofcentralprojectionofthefirstformmalegonopodlessthanequaltomesial.process.

Theboxclawcrayfishissimilartothemountainmidgetcrayfishanduplandburrowingcrayfish.Themountainmidgetcrayfishhassmallereyesandtheuplandburrowingcrayfishisusuallyverycolorfulwithintenseredsandblues.Otherspeciesinthebasineitherhavelateralspinesatthecervicalgroove,denticlesthatextendthelengthofthechelae“fingers”,ormorethanonewelldevelopedrowoftuberclesonthechelaepalm.

Color:Thecoloroftheboxclawcray-fishisusuallybrown.Thebodyandabdomen.are.a.solid.brown.or.brown-green.Thechelaearebrownbutcanhaveanorangetint.Thespeciescanbelightincolor.Thelegsarealwaysbrownishtocreamcoloredandneverblue.Tuberclesonthechelaefingersarelightercoloredthanthebackgroundandareusuallyayellowishorcreamcolor.Older,individualscanbeverydarktoblack.due.to.staining.by.organic.matter..Photo by Chris Lukhaup.

Distribution:TheboxclawcrayfishisawidelydistributedspeciesandcanbefoundinsoutheasternKentuckyintheCumberlandandKentuckyRiverbasins,easternTennesseeintheTennesseeandCumberlandRiverbasins,andthenortherncornersofGeorgiaandAlabamaintheSandMountainareaoftheTennesseebasin.WithintheObed/Emorybasinitisfoundthroughoutthearea.

Ecology/Life History: Very.little.is.knownaboutthisspecie’slifehistory.Reproduction.may.take.place.from.spring.tofall.Eggproductionhasneverbeenobserved.Boxclawcrayfishliveinsmallsizedstreamswithrockysubstrateswheretheyburrowunderrocksandintothebanks.Thebestpopulationsarefromstreamswithextensiveforestcover.Foodpreferences.as.well.as.life.span.are.un-known.Theydonotappeartorequireascoldofwaterasthemountainmidgetcrayfish.

Hairyfoot crayfishCambarus (Jugicambarus) crinipesIdentification:Keycharactersaredenticalsextendinglengthofchelae“fingers”,nolateralspinesonrostrum,onerowoftuberclesonthepalm,wideareola,lengthofcentralprojectionofthefirstformmalegonopodequaltomesialprocessandlackingasubappicalnotch.

TheHairyfootcrayfishlooksliketheObedRiverandEmoryRivercrayfishes.Theonlysurewaytoreliablytellthisspeciesfromtheothertwoistoexaminethefirstformmalegonopod.ObedRivercray-fishhaveasubappicalnotchonthecentralprojectionandEmoryRivercrayfishhaveacentralprojectionhalfthelengthtothemesialprocess.Otherspeciesinthebasinhavelateralspinesontherostrumoraros-trumthatisnotaccuminatebutsharplyangledneartheend,havetwodistinctrowsoftuberclesontheinneredgeofthechelae’spalm,ordonothavedenticalsextendingthelengthofthechelae“fingers”.

Color:Thecolorofthehairyfootcray-fishisratherdrab.Thebody,legs,che-lae,andabdomenareusuallyamottledbrown,brownishgreen,orbrownishor-ange.Shadingcanbeverydarkandthespeciesisrarelylightincolor.Recentlymoltedindividualsmayhaveorangeorredfingertips.Tuberclesontheche-laefingersarelightercoloredthanthebackgroundandareusuallyayellowishorcreamcolor.Older,un-moltedindi-viduals.can.be.very.dark.to.black.due.to.staining.by.organic.matter.

Distribution:ThehairyfootcrayfishiswidelydistributedinTen-nesseeandcanbefoundintheObey,Emory,andBigSouthForkCumberlandRiverbasinsinCumberland,Fentress,Morgan,Over-ton,Putnam,andScottCountiesofTennessee.WithintheObed/EmorybasinitisconfinedtoClearCreek.

Ecology/Life History: Very.little.is.knownaboutthisspecie’slifehistory.Itisknownthatreproductiontakesplaceinthefall.and.possibly.spring..Egg.production.is.lowastheeggsarelargeandfewinnum-ber.Hairyfootcrayfishliveinsmallandmidsizedstreamswithrockysubstrateswheretheyhideunderrocks.Inhighgra-dientareas,whereflowsarestrong,theyarefoundbothatthestreamedgesandmidstreamwheretheyburrowunderrocks.Inlowgradientstreamstheycanbefoundintheopenstreamandunderrocks.

Obed River crayfishCambarus (Jugicambarus) species.A

Identification:Keycharactersaredenticalsextendinglengthofchelae“fingers”,nolateralspinesonrostrum,onerowoftuberclesonthepalm,wideareola,asubappicalnotchonthecentralprojectionofthefirstformmalegonopod,andastronglydefectedmesialprocess.

TheObedRivercrayfishlooksliketheEmoryRivercrayfishandhairyfootcrayfish.Theonlysurewaytotellthisspeciesfromtheothertwoistoexaminethefirstformmalegonopod.ObedRivercrayfishhaveasubappicalnotchonthecentralprojection,hairyfootcrayfishdonot,andEmoryRivercrayfishhaveacentralprojectionshorterthanthemesial.Otherspeciesinthebasinhavelateralspinesontheros-trum,twodistinctrowsoftuberclesontheinneredgeofthechelae’spalm,ordenticlesextendingpartwaydownthechelae“fingers”.

Color:ThecoloroftheObedRivercrayfishisalsoratherdrab.Thebody,legs,chelae,andabdomenareusuallyamottledbrown,brownishgreen,orolivegreen.Shadingcanbeverydarktomoderatedark.Itisrarelylightincolor.Recentlymoltedindividualswillhaveorangeorredfingertips.Tuberclesonthechelaefingersarelightercoloredandareusuallyayellowishcolor.Olderindividuals.can.be.very.dark.to.black.due.to.staining.by.organic.matter..Photo by Zac Loughman.

Emory River crayfishCambarus (Jugicambarus) species.B

Identification:Keycharactersaredenticalsextendinglengthofchelae“fingers”,nolateralspinesonrostrum,onerowoftuberclesonthepalm,wideareola,centralprojectionofthefirstformmalegonopodhalfthelengthofmesialprocessandwithasubappicalnotch.

TheEmoryRivercrayfishalsolookslikethehairyfootcrayfishandObedRivercrayfish.Theonlysurewaytotellthisspeciesfromtheothertwoistoexaminethefirstformmalegonopod.ObedRiverandhairyfootcrayfishhaveacentralprojectionequalinlengthtothemesialprocess.Otherspeciesinthebasineitherhavelateralspinesontherostrum,twodistinctrowsoftuberclesontheinneredgeofthechelae’spalm,ordenticlesextendingonlypartwaydownthechelae“fingers”.

Color:ThecoloroftheEmoryRivercrayfishisratherdrab.Thebody,legs,chelae,andabdomenareamottledbrown,brownishgreen,orolivegreen.Shadingcanbedarktomoderatedark.Shadingisrarelylightincolor.Recentlymoltedindividualsmayhaveorangeorredfingertips.Tuberclesonthechelaefingersarelightercoloredthantheback-groundandareayellowishorcreamcolor.Older,individualscanbeverydark.to.black.from.staining.by.organic.matter..Photo by Zac Loughman.

Tanback crayfishCambarus (Hiaticambarus) girardianus

Identification:Keycharactersareadistincttuftofhairsatbaseofimmovable“finger”,smallspinesoncarapacesidesatcervicalgrooveandlateraledgesofrostrum,wideareola,andwidelygapingchelae“fingers”.

TheTanbackcrayfishissimilaringeneralappearancetothebigclawandrustycrayfish,twospeciesintheObed/Emorybasinthatarefromadifferentgenus.Allthreespeciespreferlargerstreamsandriversandareadaptedtothattypeofenvironment.Thetanbackcrayfishistheonlyspeciesinthebasinthathasadistincttuffofhairsatthebaseoftheimmovable“finger”ofthechelae.Inaddition,maletanbackcray-fishhaveagonopodwithtwoelementsrecurvedata900.angle.instead.ofpointinginlinewiththemainshaft.

Color:Thecolorofthetanbackcray-fishisshadesofbrownandgreen.Twodarkbrownsaddlesrunacrosstheback,oneatthecervicalgrooveandoneattheposteriormargin.Therostralmar-ginsarereddishbrownandtuberclesonthechelae“fingers”areyellow.Somelarge.individuals.take.on.a.metallic.blue.sheenonthechelae.Colorpatternsontheabdomencreateascallopedappear-ance.Afewbluephaseindividualshavebeen.observed.

Distribution:ThetanbackcrayfishiswidelydistributedintheTen-nesseeRiveranditstributariesfromnortheastMississippitoKnox-villeTennessee.IntheObedareathebestpopulationsarefoundinthelargerriverportionsoftheEmoryRivermainstemdownstreamoftheObedRiverconfluence.PopulationshavealsobeenrecordedfromtheLittleEmoryRiver,DaddysCreek,andupperObedRiver.Agooddealofvariationisseeninthephysicalappearanceandhabitatpreferencesofthisspecieswithinitswiderange.

Ecology/Life History:IntheObedEmoryRiversystemthetanbackcrayfishprefersthelargerwaterbodiesofthemainstemwhereitlivesunderthelargerflatrocksinthevicinityofrifflesandrapids.Itisnotfounddirectlyintherapidsandrifflesbutattheheadandfootofsuchareaswhereitburrowsunderrocks.Thefoodofthisspecies.is.unknown..Mating.appears.to.oc-curinthespringandfallwitheggproduc-tioninspring.Thespecie’slifespanmaybethreetofouryearsaccordingtoH.H.HobbsJr.

Valley flame crayfishCambarus (Depresicambarus) deweesae

Identification:Keycharactersareanobliteratedareola,suborbitalangleobsolete,tworowsoftuberclesonchelaepalm,nolateralspinesonrostrumorcervicalgroove,centralprojectionoffirstformmalegonopodwithoutsubapicalnotchandshorterthanmesialprocess.

Thevalleyflamecrayfishiscloselyrelatedtoandphysicallysimilartothetriangleclawandambiguouscrayfish.Allthreecanhavetworowsofpalmertubercles.Thetriangleclawcrayfishhasawide,openareolaandtheambiguouscrayfishhasanarrowareolathatisusuallynarrowlyopenthoughsomeindividualshaveshownclosedobliter-atedareolas.Valleyflamecrayfishcanbedistinguishedfromthornytailcrayfishbytheabsenceofoverhangingspinesonthetailandonlytwowellorganizedrowsoftuberclesonthechelaepalm.

Color:Thecolorofthevalleyflamecrayfishisratherstraightforward.Allbody.parts.and.appendages.are.some.shadeofred.Tuberclesandthemarginsofjointsareusuallyalighterredororange.InKentucky,somepopulationshavebeenrecordedthathaveanoverallbluebodyandappendageswithredtu-bercles,jointmargins,androstrumandpostorbitalridges.ThiscolormorphhasnotbeenobservedinthesmallTennes-see.populations.

Distribution:ThevalleyflamecrayfishisfoundonlyintheRidgeandValleyProvinceofthelowerEmoryRiverdrainagebasinintheLittleEmoryRiverarea.CurrentlythereareonlyafewsitesfromwhichthisspecieshasbeencollectedinTennessee.TwelvelocalitiesfromfourdifferentareasofKentuckyhavebeenreportedbyTaylorandSchuster.Itislikelythatthisspeciesismuchmoreabundantthatpresentlyknown.OnepopulationnearOakRidgenumberedinthehundredsofburrowsinlessthanaoneacrearea.

Ecology/Life History: Thisspeciesisaprimaryburrowerandhasneverbeenobserved.outside.its.burrow.in.standing.water.Ithasbeenseenabovegroundonrainyspringnightsmovingabout.Burrowsare.located.in.wetland.like.areas.associ-atedwithspringsorseepssuchaspicturedabove.Theburrowsaresimplewithoneortwoentrances,asingelargechamberaboutonefootdeep,andmayhavesmallersidechambersortunnels.Foodpreferencesandlife.span.are.unknown..One.gravid.female.hasbeenobservedinspring.

Triangleclaw crayfishCambarus (Depresicambarus) sphenoides

Identification:Keycharacteristicsareopenareola,tworowsoftuber-clesonchelaepalm,nolateralspinesonrostrumorcervicalgroove,suborbital.angle.acute.

ThisisoneofthethreeObedareacrayfishspecieswithtriangularshapedchelae.Allthreespecieshavetworowsoftuberclesonthechelaepalmandnolateralspinesontherostrumorcervicalgroove.Withinthisgroup,thetriangleclawcrayfishistheonlyonewithanacutesuborbitalangle.Italsohasthewidestareola.Thevalleyflameandambiguouscrayfishbothhaveverynarroworobliteratedareola.Othercrayfishspeciesinthebasinhaveonlyonerowofpalmertu-bercles,atuftofhairatthebaseoftheouterchelaefinger,orlateralspinesontheendoftherostrum.

Color:Thetriangleclawcrayfishisalmostalwayssomeshadeofbrown,green,orgreenishbrown.Thetipsofthechelaefingersarefrequentlyor-angetored.Tuberclesonthechelaearealighterbrownorcreamcolor.Theabdomenisusuallydarkercoloredthanthebodyandsometimeshasagreen-ishhue.Youngerindividualsmaybemottledontheheadandbodyandcanhaveabandedpatterntotheabdomenwithapairofdarkdorsalbandsrunningthelengthofthetail.

Distribution:ThetriangleclawcrayfishisfoundthroughouttheSouthwesternAppalachianecoregion(bluecoloredareaofmap)oftheObedEmoryRiverbasin.ItdoesnotappeartoinhabittheRidgeandValleyarea(yellowarea)ortheCentralAppalachianecoregionareas(greenarea).OutsideoftheimmediateareaitisfoundontheCumberlandPlateauofKentuckyandTennesseeintheKentucky,Cumberland,andTennesseeRiverbasins.

Ecology/Life History: Thetriangleclawcrayfishdisplaystwobasiclifestyles.Oneistoburrowintostreambanks(especiallythoseofclay)insmalltomediumsizedstreams.Theotheristoliveinmidstreamburrowingunderrocks.Insuchstreamswater.temperatures.must.remain.cool.to.coldsuchaswouldbefoundinaspringfedstream.Thespeciesistolerantofmildenvironmental.disturbance..Mating.occurs.inthespringandfallandeggproductionhasbeenobservedinspring.Foodprefer-encesareunknownalongwithlifespan.

Ambiguous crayfishCambarus (Depresicambarus) striatus

Identification:Keycharacteristicsareanobsoletesuborbitalangle,anarrowareola(notnormallyobliterated),tworowsofpalmertuber-cles,nocervicalorrostrumlateralspines.

Asimpliedbyitscommonname,thisspeciesishighlyvariable.TherearefewpopulationsintheObedareasovariationisnotaprobleminthebasin.Withinthebasinthisistheonlyspecieswithanarrowareolathatisnotcompletelyclosed,twoeasilyseenrowsoftuberclesonthechelaepalm,andnolateralspinesontherostrum.Thethornytailcrayfishdiffersfromthisspeciesbutwithitsspinesthatoverhangthetail’smarginandlargenumberoftuberclesonthechelaepalm.Thetriangleclawcrayfishhasawiderareolaandacutesuborbitalangleandthevalleyflamecrayfishhasanobliteratedareola.

Color:Theambiguouscrayfishisauni-formbrowntobrownishgreeninadults.Youngindividuals(likethetrianglecrayfish)candisplaytwobarkbrowntoblack-brownstripesontheabdomen.Thechelaetipswillbereddishtoorangeandthetubercleslightorangetocream.Somecanhaveamottledappearance.Thelegswillbealightbrown,lightgreen.or.cream.color..Rostral.margins.areusuallyalightercolorthanthebodyandmaybeorange,red,orlightbrown.Photo G.W. Stocker.

Distribution: Theambiguouscrayfishisfoundinthelowereleva-tionsoftheSouthwesternAppalachiansEcoregiononthebanksoftheEmoryandObedRiversandClearCreek.Thereareonlyfourcollectionssitesforthisspeciesinthebasinbutitislikelythatitismuchmorecommon.Itcanbeadifficultspeciestocollectbecauseof.its.excellent.digging.abilities.and.is.likely.under.represented..FurthercollectinginthebasinwillresultinmorerecordsfortheambiguouscrayfishanditwilllikelybefoundthroughouttheSouthwesternAppalachianEcoregion.

Ecology/Life History: Theambiguouscrayfishisalmostalwaysfoundinabur-row.Itsburrowsarefoundontheedgesofstreamsandriversusuallywheresomegroundwaterisseepingintothestream.Inotherpartsofitsrangeithasbeenreportedin.open.stream.environments.from.under.rocks.and.logs.or.burrowing.in.wetland.habitats.Femaleswitheggshavebeencollected.in.August.and.October..Firstform.maleshavebeenreportedforallmonthsexceptJuneandAugust.Foodandlifespan.are.unknown.

Bigclaw crayfishOrconectes (Procericambarus) placidus

Identification:Keycharactersaretwolateralspinesatdistalendofrostrum,cervicalspinesonsideofcarapacejustposteriortocervicalgroove,mandiblewithteeththroughoutlength.

TherearetwospeciesofOrconectesintheObedEmoryRiverbasin,bothofwhichareintroducedinvasivespecies.Bothspecieshavelateralspinesontherostrumandcervicalgroove.Oneotherspeciesinthebasin,thetanbackcrayfish,candisplaysuchspinesbutthisspecieshasatuftofhairsatthebaseofitsoutsidechelaefinger.Thebigclawcrayfishcanbedistinguishedfromtherustycrayfishbyexaminingthemandible(theinnermostmouthpart).Thebigclawcrayfishhasteethonallofthemandible’sedgewhiletherustycrayfishhasabladelikeedgeonthedistalhalfandthuslacksteeththere.

Color:.Background.coloration.is.some.shadeofbrownorgreen.Therearetwodarkbrowntoblacksaddles,atthecer-vicalgrooveandthebackofthecara-pace.Thechelaehaveorangeorredtipswithablackbandjustbehind.Chelaetuberclesandspinesonthebodyandappendagesarelighttanorcream.Thelegsarealightercolorofthecarapacebackgroundcolor.Theabdomenispat-ternedwithrowsofdarkmarkingsandreddishbandsateachsegment’sposte-rior.edge..Photo by G.W. Stocker.

Distribution:CurrentlythebigclawcrayfishisconfinedtothelowergradientwatersoftheupperObedRiver.Thespeciesisnotnativetothebasin.In1974collections(madebyDr.D.H.Stans-bury)onlyObedRivercrayfishwererecordedintheupperObed.ThisworkfoundthatallObedRivercrayfishhadbeenreplacedbybigclawcrayfishinupperObedmainstemwaters.Itisnotknownifthisspecieswillcontinuetoexpanditsrangeinthebasin.InitsnativerangeitisfoundinthelowerandmiddleCumberlandandTennesseeRiverbasinsnorthandwestoftheObedRiver.

Ecology/Life History:.In.its.native.range.thebigclawcrayfishisfoundinallsizesofstreams.Itseemstoavoidhighgradientwaters.IntheObed,itcurrentlyoccupieslowgradientstreamsshowingsignsofnutrientenrichmentwhereitlivesamongstandunderrocks.Howfarthespecieswillexpanditsrangeinthebasinisunknown.Itispossiblethat80to90percentofthebasin.could.be.invaded.by.bigclaw.cray-fishwhichcouldresultintheextinctionofEmoryandObedRivercrayfishes.Thebigclaw.likely.arrived.via.bait.bucket.

Rusty crayfishOrconectes (Procericambarus) rusticus

Identification:Keycharactersaretwolateralspinesatdistalendofrostrum,cervicalspinesonsideofcarapacejustposteriortocervicalgroove,mandiblewithbladelikeedgeondistalend.

ThisisanotherintroducedinvasivespeciesintheObedEmorybasin.Therustycrayfishalsohaslateralspinesontherostrumandcervi-calgroove.Oneotherspeciesinthebasin,thetanbackcrayfish,candisplaysuchspinesbutthetanbackhasatuftofhairsatthebaseofitsoutsidechelaefinger.Therustycrayfishcanbedistinguishedfromthebigclawcrayfishbyexaminingthemandible(theinnermostmouthpart).Thebigclawcrayfishhasteethonallofthemandible’sedgeandtherustycrayfishhasabladelikeedgeonthedistalhalfandthuslacksteeththere.

Color:Rustycrayfishhavechelaecol-orationsimilartobigclawcrayfishwithanorangeorredtipandanadjacentblackbandandlightcoloredtubercles.Thebodylacksthecervicalsaddlebandbutfrequentlyhasthebandatthepos-teriorcarapaceedge.Italsohaslateralrustycoloredblotchesontheposteriorcarapace..Background.coloration.is.brown,green,orrustyred.Thelegsarenormallybluishorgreen.Somepopula-tionshavestrongbluishtintstotheiroverall.body.coloration.

Distribution:OnlyonespecimenoftherustycrayfishhasbeencollectedintheObedEmoryRiverbasinfromLaurelBranchattheOakdaleCityPark.Itisnotknownifthisspecimenrepresentsanestablishedpopulation.OtheradjacentcollectingsitesintheEmoryRivermainstemfailedtoyieldrustycrayfish.Itislikelythatapop-ulationexistsomewhereintheLaurelBranchbasinpossiblyinoneofthelocalponds.TherustycrayfishhasbeenwidelyintroducedinNorthAmericaandhasproventobeanaggressiveinvader.Ifitbecomesestablisheditwillspreadwidelyinthebasin.

Ecology/Life History:Therustycrayfishpreferslowergradient,nutrientenrichedstreamsandlakesandponds.Thespecieshasdramaticnegativeimpactsonaquaticvegetationandhasbeenknowntoelimi-nateplantcommunities.Suchecologicalchangesinvariablyhavenegativeeffectsontheothermembersoftheecosystem,especiallyfish.Rustycrayfishareknowntoeliminatenativecrayfishpopulations.Theyappeartoconsumeaquaticplantsaswellasinsectsandotherbenthicorgan-isms.Theyreproduceprolifically.

HelpfulCrayfishLiterature

The Crayfishes of Kentucky.C.A.TaylorandG.A.Schuster.2004.PublishedbytheIllinoisNaturalHistorySurvey,SpecialPublicationnumber28.ThisbookisstillavailablefromtheIllinoisNaturalHistorySurveyfor$20.00.ItcontainsagreatdealofinformationonmanyofthecrayfishspeciesfoundintheObedRiverarea.

The Crayfishes of Georgia.H.H.HobbsJr.1981.PublishedbySmithsonianInstitutionPress,SmithsonianContributionstoZoologynumber318.ThisbookisnolongeravailablebutmaybefoundatUniversityandCollegelibraries.Itcontainsextensive,detailedinformationonsomeoftheObedspeciesandmanyTennesseespecies.

The Crayfishes of West Virginia.R.F.Jezerinac,G.W.Stocker,&D.C.Tarter.1995.PublishedbytheOhioBiologicalSurvey,BulletinoftheOhioBiologicalSurveyNewSeriesVol.10number1.Thisbookisstillavail-ablefromtheOhioBiologicalSurveyforabout$10.Itcontainsagreatdealofmorphometricinformation.

An Illustrated Checklist of the American Crayfishes.H.H.HobbsJr.1989.PublishedbySmithsonianIn-stitutionPress,SmithsonianContributionstoZoologynumber480.ThisbookisnolongeravailablebutmaybefoundatUniversityandCollegelibraries.ItcontainssomeinformationonhabitatanddistributionwithlinedrawingsofeveryspeciesknownfromNorthandSouthAmerica.IthasmostTennesseespecieslistedinitthatweredescribedpriorto1990.

Conservation status of crayfishes of the United States and Canada.C.A.Tayloretal.1996.PublishedbytheAmericanFisheriesSocietyinFisheries,Volume21,number4.ItmaybefoundatUniversityandCollegelibraries.ThepapercontainsinformationonallspeciesnorthofMexicoincludingtheirgeneraldistributionandconservationstatus(orrarity)anddiscussesthosethingsthatthreatentheirexistence.IthasbeenrevisedandwillbepublishedagaininFisheriesin2007.