Field Key to Sharks Encountered in the U.S. Atlantic Bottom Longline Shark Fishery and by Recreational Anglers
How to Use this Key:
- Start with the first question. Decide whether the statement in the first box (1a) or the the second box (1b) best describes the characteristics of the shark you are trying to identify. (See this page on shark anatomy if you need help.)
- Click on the link in the row that best matches your shark. Your choice will lead you to a link to the species profile page for that shark or the next appropriate pair of questions.
- Work through the questions, each time choosing the characteristic that best matches your shark from the two choices. This will lead you to the final choice which identifies the shark.
| 1a) Body flattened dorso-ventrally, skate-like in appearance | 
Atlantic Angel Shark
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| 1b) Body round in cross section | Question 2 |
| 2a) Seven gill slits, single dorsal fin |
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| 2b) Six gill openings, single dorsal fin | Question 3 |
| 2c) Five gill openings, two dorsal fins | Question 4 |
| 3a) Snout short, blunt and broad; eye small; distance between rear base of dorsal fin and origin of caudal fun about 1.5 to 2.0 times length of dorsal fin base; lower jaw with six rows of teeth |
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| 3b) Snout more pointed and narrow; eye large; distance between rear base of dorsal fin and origin of caudal fin about 2.5 to 3 times length of dorsal fin base; lower jaw with five rows of teeth |
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| 4a) Anal fin absent | Question 5 |
| 4b) Anal fin present | Question 9 |
| 5a) No spines on dorsal fins |
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| 5b) Both dorsal fins with spines | Question 6 |
| 6a) First dorsal spine over or posterior to inner corner of pectoral fin; midpoint of base of pelvic fin much nearer to origin of second dorsal fin than to rear base of first dorsal fin | Question 7 |
| 6b) First dorsal spine almost over midpoint of inner margin of pectoral fin; midpoint of base of pelvic fin about midway between rear base of first dorsal fin and origin of second dorsal fin | Question 8 |
| 7a) First dorsal fin noticeably larger than second dorsal fin; anterior nasal flap with small and narrow secondary lobe; usually conspicuous white spots present on sides of body |
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| 7b) Second dorsal fin nearly as large as first dorsal fin; anterior nasal flap with large and broad secondary lobe, almost barbel-like; color dark without conspicuous white spots on sides of body |
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| 8a) Inner margins of pectoral fins deeply concave, inner corners acutely pointed. |
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| 8b) Inner margins of pectoral fins weakly concave, inner corners at approximately right angles |
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| 9a) Caudal peduncle with one or more keels or ridges | Question 10 |
| 9b) Caudal peduncle without keels or ridges | Question 17 |
| 10a) Two keels present, a strong keel on caudal peduncle and a short secondary keel on caudal base |
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| 10b) One keel or ridge on caudal peduncle, no secondary keel on caudal base. | Question 11 |
| 11a) Mouth located on tip of snout; coloration a series of round spots and narrow transverse stripes; three to four large ridges along back and sides | 
Whale Shark
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| 11b) Mouth inferior; color not as above; no such ridges along back and sides | Question 12 |
| 12a) Keel on caudal peduncle a weakly developed ridge | Question 13 |
| 12b) Keel on caudal peduncle well developed | Question 14 |
| 13a) Spiracle present; first dorsal fin originates even with rear bases of pectoral fins; pectoral fins moderately long; coloration irregular bands or elongated spots |
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| 13b) Spiracle absent; first dorsal fin originates well past rear bases of pectoral fins; pectoral fins very long; coloration uniformly cobalt blue |
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| 14a) Gill slits long, extending almost full height of head; teeth minute and hooked |
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| 14b) Gill slits shorter, not extending full height of head; teeth large, prominent and erect | Question 15 |
| 15a) Origin of anal fin placed well behind rear base of second dorsal fin; all teeth strongly serrated, the uppers flat and broadly triangular; black spot usually present in axils of pectoral fins; coloration dark grey above and laterally with a white belly and underside of snout |
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| 15b) Origin of anal fin placed at mid or rear base of the second dorsal fin; teeth smooth-edged, not greatly flattened, narrowly triangular and blade-like; black axil spot always lacking; coloration cobalt blue above and laterally with belly and underside of snout white | Question 16 |
| 16a) Snout greatly pointed; pectoral fins much shorter than head; anal fin origin under mid base of second dorsal fin; symphysial teeth of both jaws recurved; eyes small |
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| 16b) Snout bluntly pointed; pectoral fins as long as head; anal fin origin under rear base of second dorsal fin; symphysial teeth straight or only slightly recurved; eye large |
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| 17a) Head flattened dorso-ventrally and expanded laterally, hammer- or spade-shaped | Question 18 |
| 17b) Head not dorso-ventrally flattened and expanded laterally | Question 21 |
| 18a) Head margin rounded, spade-shaped |
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| 18b) Head hammer-shaped | Question 19 |
| 19a) Head margin broadly convex without a noticeable indentation at tip of snout |
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| 19b) Head margin broadly convex to straight with noticeable indentation at tip of snout | Question 20 |
| 20a) Second dorsal fin small, free rear tip about twice the vertical height of fin; first dorsal fin tall, narrowly pointed, posterior margin strongly falcate; pelvic fin margin straight to weakly falcate |
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| 20b) Second dorsal fin large, free rear tip,shorter or equal to vertical height of fin; first dorsal broadly triangular, posterior margin nearly straight to slightly falcate; pelvic fin margin strongly falcate |
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| 21a) Dorsal lobe of caudal fin greatly elongated, being nearly as long as the distance from tip of snout to precaudal pit | Question 22 |
| 21b) Dorsal lobe of caudal fin not elongated, being much shorter than the distance from tip of snout to precaudal pit. | Question 23 |
| 22a) Head flattened between eyes with a pronounced, deep groove on nape above gill slits; eyes very large, horizontal diameter is less than vertical diameter, with orbits extending onto top of head; rear tip first dorsal fin origin lies midway between rear pectoral fin base and terminates anterior to origin of pelvic fins |
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| 22b) Head arched between eyes, no grooves present on nape above gill slits; eEye smaller, horizontal diameter is approximately equal to vertical diameter, not extending onto top of head; rear tip first dorsal fin origin lies much closer to rear pectoral fin base than toterminates over or beyond origin of pelvic fins |
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| 23a) First and second dorsal fins of about equal in size | Question 24 |
| 23b) The two dorsal fins unequal in size, the first noticeably larger than the second | Question 28 |
| 24a) A low dermal ridge present on midline of dorsal surface between first and second dorsal fins | Question 25 |
| 24b) No low dorsal dermal ridge present on midline of dorsal surface between first and second dorsal fins | Question 26 |
| 25a) Upper labial furrows shorter than lower labial furrows; corner of lower lobe of caudal fin pointed and directed rearward; distal margin of pectoral fin deeply concave |
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| 25b) Upper labial furrows slightly longer than lower labial furrows; corner of lower lobe of caudal fin broadly rounded; distal margin of pectoral fin nearly straight |
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| 26a) Head pointed; large pointed and recurved teeth protrude from mouth |
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| 26b) Head blunt; teeth pointed but not recurved or protruding from mouth | Question 27 |
| 27a) Large and obvious barbel present on margin of each nostril; no precaudal pit; teeth pavement-like with central ridge |
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| 27b) No barbel on margin of each nostril; precaudal pit present; teeth erect with serrations on larger individuals, smooth on young |
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| 28a) Dorsal, pectoral, and caudal fins tipped with white (black tipped in juveniles); first dorsal fin broadly rounded; pectoral fins large, paddle-shaped with rounded tips |
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| 28b) Fins not white tipped, first dorsal and pectoral fins not broadly rounded | Question 29 |
| 29a) Anal fin origin anterior to second dorsal fin origin; larger individuals with white lateral spotting; pectoral fins with white margins |
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| 29b) Anal fin origin posterior to or even with second dorsal fin origin; lateral white spotting lacking at all sizes | Question 30 |
| 30a) Low ridge present between first and second dorsal fins | Question 31 |
| 30b) Low ridge absent between first and second dorsal fins | Question 37 |
| 31a) Length of fin near tip of second dorsal fin more than two times the vertical height of the fin; first dorsal fin short with rounded tip |
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| 31b) Length of free tip of second dorsal fin in two times or less vertical height of the fin; first dorsal fin taller and not notably rounded | Question 32 |
| 32a) Snout long and pointed, distance between nostrils on underside of snout is 0.5-0.6 the length of the snout; eyes large and green in life |
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| 32b) Snout shorter and broader, distance between nostrils on underside of snout is greater than 0.6 the length of the snout (tip of snout to mouth); eyes smaller and never green in life | Question 33 |
| 33a) First dorsal fin located forward on body, its origin over or anterior to pectoral fin axil (or at least closer to the axil than to its free rear tip) | Question 34 |
| 33b) First dorsal fin located farther back on body, its origin over or posterior to the free rear tip of the pectoral fin (or at least closer to free rear tip than to axil) | Question 35 |
| 34a) First dorsal fin large, vertical height greater than 10% of total length; snout moderately long and rounded, its length about half the height of the first dorsal fin |
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| 34b) First dorsal fin smaller, vertical height less than 10% of total length; snout longer and rounded or bluntly pointed, its length almost the same as the height of the first dorsal fin |
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| 35a) Free rear tip of second dorsal fin short, its length about equal to the height of the fin; color grayish brown to olive gray in life with pronounced dark edging on margins of caudal fin, especially the lower lobe, and on tips of anal and second; snout short and broadly rounded; upper teeth with narrow cusps, 13 upper teeth and 12 lower teeth on each side of the jaw |
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| 35b) Free rear tip of second dorsal fin longer, its length nearly 1.5 the height of the fin; color grayish brown to gray in life without pronounced dark edging on margins of caudal fin, especially the lower lobe, and on tips of anal and second dorsal fin;dorsal fin; snout moderately long; upper teeth with narrow cusps, 13 upper teeth and 12 lower teeth on each side of the jaw | Question 36 |
| 36a) First dorsal fin high with nearly straight anterior margin and pointed tip, snout length about 3/4 or less of the fin height in all sizes; second dorsal fin somewhat larger, length of its free rear tip 1.3-1.7 times its height |
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| 36b) First dorsal fin lower with a rounded anterior margin and slightly rounded tip, snout length about equal to or greater than the fin height in all but large adults; size of second dorsal fin somewhat smaller, length of its free rear tip 1.6-2.1 times its height |
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| 37a) Snout short and broadly rounded,length of snout much shorter than width of mouth; upper teeth broadly triangular and serrated, without notches on outer margins | 
Bull Shark
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| 37b) Snout longer, length of snout equal to or longer than width of mouth; upper teeth erect and smooth or with fine serrations, or with narrow, oblique cusps and serrated edges | Question 38 |
| 38a) Black or dusky spot on tip of snout, more prominent in young and more diffuse in larger individuals; coloration yellowish green to brownish in life, fading to grey after death; teeth with narrow, oblique cusps and serrated edges |
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| 38b) No black or dusky spot on tip of snout; teeth erect and smooth or with fine serrations | Question 39 |
| 39a) No black or dusky tips on fins; teeth erect, narrow, and smooth |
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| 39b) Black or dusky tips on fins; teeth with broader base and fine serrations | Question 40 |
| 40a) Anal fin with black tip except in young (less than 70 cm total length); first dorsal fin origin lies at level of or behind free tip of pectoral fin; snout long; height of first dorsal fin less than length of snout except in large adults, when it become about the same or slightly larger; eye small, horizontal diameter is one-fourth or less than the length of first gill opening |
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| 40b) Snout shorter; height of first dorsal fin always greater than length of snout, snout about 2/3 of first dorsal fin height in large adults; eye larger, horizontal diameter one third greater than length of first gill opening |
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