standardised keyfeatures by scientific experts. species. looking The keyfeatures usedinthecouplets have beenidentified and as verified andrayssharks that are eithernotalready orto helpdistinguishamongsimilar known, This keyhasbeendeveloped to provide asimplestandardised process for identifying separate andrays). removes ofspeciesoridentifies onefrom aselection the rest (e.g. keystep 1,below, used to year andacross therange )andclearormeasurable. Eachcouplet isabranch that either live anddeadforms andbothsexes ofthespecies),consistent (are present throughout the exclusive couplets) identifying orcontrasting features that are reliable (are always found in A dichotomous keyrelies onapathway ofsteps ofpaired alternative (mutually descriptions featuresseen external hasbeendeveloped training. for fielduseandobserver To improve identification and oftheshark ray speciesadichotomous keybasedon readily identification Key forsharkandray species key intraining willstandardise theprocess followed to identify andrays. by sharks observers illustrations in thefollowing canthenbeusedto confirm identification. section Theuseofthis pelagic andrays. sharks The keyshouldbeusedroutinely to identify speciesandthedetailed The keyfor andray shark identification has43 couplet pairsthat identify 44species of to distinguishthefinalspeciespair. species, suchasinthefamilyCarcharhinidae, identification takesup to 26steps of couplets family, identifies thespeciesfrom theothers. thekeyquickly Where there are many similar also affectsthenumberofsteps to identify aspecies. Where there isonlyonespeciesofa sharks, andtheidentification groups thespeciesintheirfamilies. The useofkey features The keycouplets identify clearfeatures for identification the andso systematicsreflect of gills onsideof head go to step 2 gills onunderside ofhead go to step 37 7 1 Key steps Step Key steps 4 3 2 8 5 gill openingsoneachsideofhead 6 gill openingsoneachsideofhead dorsal nswithoutspines dorsal nswithsmallspines Hexanchus griseus(Bluntnose sixgillshark) Zameus squamulosus (Velvet dog sh) (sometimes small) anal npresent anal nabsent 1 dorsal n 2 dorsal ns go to step 6 go to step 4 go to step 3 go to step 5 p. 25 p. 24 not -like and shorter relatively broad, lateral bladesofhead and wing-like long,very narrow lateral bladesofhead no dark collarno dark around head collardark around headat gill region dorsal nslocated well backonbody head hammer-shaped go to step 7 rst dorsalwell infront ofpelvic n (Black shark, Kite n licha(Blackshark, shark) Dalatias (Cookie-cutter shark)Isistius brasiliensis (Cookie-cutter head widthmuchlessthanhalf of total length rst dorsalover pelvic ns Eusphyra (Wingheadshark) blochii head widthalmosthalfoftotal length head nothammer-shaped go to step 10 go to step 8 p. 28 p. 27 p. 26 9 5 7 6 Key steps Step 10 Key steps 9 8 2 rst dorsal nsemi-falcate, onlymoderately high smaller thanorequalto thelengthof3 half oftotal length length ofcaudal ngreater thanorequalto half oftotal length length ofcaudal nmuchlessthan rst dorsalfalcate, tallinadults very 2 greater thanthelengthof3 10 nd nd dorsal nheight dorsal nheight Sphyrna zygaena hammerhead) (Smooth without amedianindentation anterior pro le ofhead rd rd gill slit p. 29 Sphyrna mokarran () Sphyrna hammerhead) lewini (Scalloped anterior pro le straight ofheadnearly with amedianindentation anterior pro le ofhead (slightly convex insmalljuveniles) anterior pro le ofheadconvex ... goto step 13 ... goto step 11 go to step 9 p. 31 p. 30 with orbits lateralwith orbits onhead eyes smaller, head withoutadeepgroove onto dorsal head surface onto dorsalheadsurface large,eyes very extending aroundextending eachside head withdeepgroove anks above andpelvicnsnotwhite pectoral ending below orbehindeye mouth notat front ofhead ending infront ofeye mouth at front ofhead anks above andpelvicnswhite pectoral and pelvicbases, orcloserto nbases pectoral base of rstdorsal naboutequidistant between pectoral labial furrows absent labial furrows present than to bases pectoral base of rstdorsal ncloserto pelvicbases (Bigeye superciliosus Alopias thresher) (Pelagic pelagicus Alopias thresher) no checkerboard colour pattern Alopias vulpinusAlopias shark) (Thresher (Whale shark) (Whale typus Rhincodon checkerboard colour pattern snout short head broad, snout elongated head narrow, straight andbroadly pectoral ns curved nscurved pectoral and sharply pointedand sharply pectoral ns nearly nsnearly pectoral go to step 14 go to step 12 pointed p. 36 p. 35 p. 34 p. 33 11 11 13 12 Key steps Step Key steps 16 15 14 12 extend onto surface ofthehead ontoextend surface large gills very attened andstrongly serrated upper teeth broadly triangular, longer thanlower lobe upper lobelessthan1.5times caudal nlunate teeth minute (White shark) carcharias (White Carcharodon Cetorhinus shark) maximus (Basking and ventral surface go to step 15 p. 37 p. 38 teeth blade-like, muchlarger teeth blade-like, without serrations upper teeth long, narrow, and head orventral surface of the gills onto donotextend surface longer thanlower lobe upper lobemore than1.5times caudal nheterocercal go to step 19 go to step 17 go to step 16 rst dorsal- norigin over baseorinnermargin ns ofpectoral rst dorsal- norigin posterior to ns pectoral (subterminal) ofthehead mouth located onundersurface mouth hugeandterminal anal norigin opposite middleofsecond dorsal n anal norigin behindsecond dorsal ninsertion dorsal n free rear tipof white patch on dorsal n free rear tipof no white patch on no secondary keeloncaudalpeduncle no secondary caudal pedunclewithtwo keels preoral longerthaneye distance diameter distinctly (Megamouth shark)Megachasma (Megamouth pelagios (Short n mako) (Short n Isurus oxyrinchus Isurus paucus(Long n mako) lower jaw to extending snouttip Lamna nasus()Lamna teeth withoutsmall teeth withsmall pectoral nslonger pectoral lateral cusplets pectoral nsmuch pectoral lateral cusplets thanorequalto go to step 18 go to step 20 shorter than shorter head length head length p. 42 p. 40 p. 41 p. 39 13 17 19 18 Key steps Step Key steps 22 21 20 14 dorsal surface ofhead dorsal surface gill onto openingsextending more thanhalfthegreatest height ofsnout large,eyes very eyelids xed, notcapable ofclosingover eyes second dorsal nsmallerthanhalfheight of rstdorsal n second dorsal nhigherthanorequalto halfheight of rstdorsal n (Bigeye noronhai Odontaspis sandtiger) Pseudocarcharias kamoharai () p. 43 p. 44 onto dorsal surface ofhead onto dorsalsurface gill openingsnotextending less thanhalfthegreatest height ofsnout eyes smaller, Triaenodon tipreef shark) (White obesus eyelids capableofclosingover eye (nictitating) go to step 22 go to step 21 go to step 23 p. 45 prominent lateral keelspresent oncaudalpeduncle brilliant bluecoloration above (whenfresh) rst dorsal nmidway andpelvic nsorcloserto between pectoral ns pectoral rst dorsal nmuchcloserto ns pelvic nsthanpectoral tapering withpointedtapering tips ns rst dorsalandpectoral ns notmottledwhite; with rounded andwhite mottledtips broad nsvery rst dorsalandpectoral extending infrontextending ofeyes upper labialfurrows long, very Galeocerdo cuvier(Tiger shark)Galeocerdo p. 46 Carcharhinus longimanus (Oceanic whitetip) (weak keelspresent intheBlueshark) lateral keelsabsent from caudalpeduncle do not extend infrontdo notextend ofeyes upper labialfurrows low lateral keelsoncaudalpeduncle Prionace glauca (Blueshark) no lateral keels go to step 24 go to step 25 go to step 26 p. 47 p. 48 15 23 25 24 Key steps Step Key steps 28 27 26 16 without white tips pelvic andcaudal ns rst dorsal n,pectoral, and posterior edges with conspicuous white tips pelvic andcaudal ns rst dorsal n,pectoral, Carcharhinus brachyurus (Bronze whaler) bent, hooked, narrow cusps largest upperteeth with no blacktipon rstdorsal n(sometimeswhite tip) if caudal nposterior edgeisblackthen rstdorsal ntip p. 52 (Silvertip shark)Carcharhinus (Silvertip albimarginatus Carcharhinus amblyrhynchos () but never withbent, hookedcusps largest upperteeth variably shaped caudal nwithprominent posterior blackedge posterior blackedgesorplain caudal nwithprominent go to step 29 go to step 27 go to step 28 p. 49 p. 51 rst dorsal ntipnarrowly rounded (notpointed) rst dorsal- ntippointed rst dorsal- norigin infront oforover free pectoral rear tips rst dorsal norigin well free behindpectoral rear tips than to insertions nfreepectoral rear tips its origin closer to backonbody, rst dorsal nlocated further its origin almostopposite ninsertions pectoral rst dorsal nlocated forward onbody, no interdorsal ridge dorsal ns(interdorsal ridge) present between ofskin ridge a distinct (longer in the Dusky shark) (longer intheDusky thansecond dorsal nheight usually shorter second dorsalfree rear tipshorter, longer thanheight ofsecond dorsal n second dorsalfree long, rear tipvery usually Carcharhinus falciformis shark) (Silky go to step 34 go to step 30 go to step 33 go to step 32 go to step 31 p. 53 17 29 31 30 Key steps Step Key steps 34 33 32 lower rst dorsaln high very rst dorsaln 18 body lessstocky body very stocky body very rst dorsal nhigher rst dorsal nlower pectoral nsrelativelypectoral straight pectoral nscurved pectoral interdorsal distinct high,very ridge interdorsal low, ridge lessdistinct Carcharhinus galapagensis (Galapagos shark) (Sandbar shark) Carcharhinus (Sandbar plumbeus Carcharhinus altimus (Bignoseshark) Carcharhinus shark) obscurus(Dusky largest upperteeth broad, triangular Carcharhinus leucas (Bullshark) largest upper teeth narrow and sometimesserrated upper teeth relatively low andinconspicuous broad andoblique relatively narrow upper teeth high andtriangular anterior nasal aps anterior nasal aps and serrated go to step 35 p. 58 p. 55 p. 54 p. 57 p. 56 rst dorsal nmay ormay nothave blacktipAND blacktipAND distinct rst dorsal nwithavery forward ninsertions ofpectoral rst dorsal norigin over orjust (height <2.2 timesininterdorsal space) rst dorsal ntaller freebehind pectoral rear tips rst dorsal norigin over orjust (height >2.2 timesininterdorsal space) rst dorsal nrelatively low elongate lobeson each sideofhead snout modi edinto apairof head notelevated above disc that joins black marking alongtheposterior margin that joinsblackmarking onlower lobe blackmarking ...caudal nwithstriking that joins the black marking onthelowerthat lobe joinstheblackmarking ...caudal ndoesnothave blackposterior margin go to step 38 Carcharhinus melanopterus(Blacktipreef shark) Carcharhinus (Common limbatus blacktipshark) lobe-like process or pairofrounded lobes lobe-like snout formed asasingle, convex, head elevated above disc Carcharhinus brevipinna (Spinnershark) usually shorter thandistance between teeth usually shorter usually tallerthandistance between teeth teeth size, ofnormal teeth inmiddlerows teeth very short, teeth inmiddlerows short, teeth very largest upperteeth without largest upperteeth with coarse basalserrations coarse basalserrations go to step 43 go to step 36 p. 59 p. 61 p. 60 19 35 37 36 Key steps Step Key steps 40 39 38 20 embedded spinepresent behinddorsal n calci ed masscontaining an present behinddorsal n no calci edmassofspine large animals, reaching well over 2mdiscwidth mouth terminal onhead dorsal to ns theplaneofpectoral spiracles long, slit-like and emanating gill from slits bothofthe fth emanating gill from slits bothofthe fth a large, black, semi-circular spot a large, semi-circular black, a small black semi-circular spot a smallblacksemi-circular go to step 39 go to step 41 mouth subterminal on ventral surface ofhead mouth subterminal onventral surface small animals, not reaching 2mdiscwidth ventral to ns theplaneofpectoral spiracles small, subcircular and Mobula birostris(Giant manta) (Reefmanta)Mobula alfredi shoulderpatches parallel anterior margin ofwhite anterior margin ofwhite curving posteriorly curving withfront ofhead shoulder patches go to step 40 go to step 42 p. 62 p. 63 by adeepnotch snout withapairofbroad lobesseparated dorsal nplain disc greyish, base oftaildepressed Rhinoptera javanica (Javan cownose ray) tail base located nearthe a smallcaudalsting double curvature anterior margin nswith ofpectoral strongly falcate ns pectoral Mobula tarapacana (Chilean devilray) Mobula thurstoni (Bent ndevilray) strong bony ridge on dorsalmidline no caudalspine dorsal n a single p. 68 p. 64 p. 66 Pteroplatytrygon violacea (PelagicPteroplatytrygon stingray) prominent white tip dorsal nwith disc blackish, down thetail spine, located farther a large caudal sting ns pectoral not separated from snout withsingleconvex rostral lobe, base oftailquadrangular moderately falcate ns pectoral or slightly convex anterior margin nstraight ofpectoral (GiantMobula mobular devilray) (Short n devilray)Mobula kuhlii (Short n usually present behind serrated caudalspine no dorsal n or withoutwhite tip on dorsalmidline weak bony ridge dorsal nwith dorsal n p. 65 p. 67 p. 69 21 41 43 42 Key steps Step