Field Key to Sharks Encountered in the U.S. Atlantic Bottom Longline Shark Fishery and by Recreational Anglers

How to Use this Key:

  1. 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.)
  2. 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.
  3. 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 Angelshark. Photo courtesy Virginia Institute of Marine Science Atlantic Angel Shark
1b) Body round in cross section Question 2

 

2a) Seven gill slits, single dorsal fin

The sharpnose sevengill shark has a narrow head with large eyes. Photo © George Burgess

Sharpnose Sevengill Shark

2b) Six gill openings, single dorsal fin Question 3
2b) Six gill openings, single dorsal fin 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

Bluntnose sixgill shark (Hexanchus griseus) being landed by shark fishing boat. Photo © Florida Museum

Bluntnose Sixgill Shark

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

Bigeye sixgill shark head view: notice the large eyes and six gill slits. Photo © John Morrissey

Bigeye Sixgill Shark

 

4a) Anal fin absent Question 5
4b) Anal fin present Question 9

 

5a) No spines on dorsal fins

Bramble shark. Image courtesy FAO

Bramble Shark

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

Spiny dogfish. Photo courtesy NOAA

Spiny Dogfish

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

Roughskin dogfish. Photo © George Burgess

Roughskin Dogfish

 

8a) Inner margins of pectoral fins deeply concave, inner corners acutely pointed.

Cuban dogfish reach a maximum total length of approximately 43.3 inches. Photo © George Burgess

Cuban Dogfish

8b) Inner margins of pectoral fins weakly concave, inner corners at approximately right angles

The longnose spurdog (above) is sometimes confused with the Cuban dogfish. Photo © George Burgess

Longnose Spurdog

 

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

Porbeagle head, also notice the white free rear tip of the dorsal fin. Photo courtesy NOAA

Porbeagle

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 Whale Shark
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

Tiger Shark. Photo © Jeremy Stafford-Deitsch

Tiger Shark

13b) Spiracle absent; first dorsal fin originates well past rear bases of pectoral fins; pectoral fins very long; coloration uniformly cobalt blue

Blue shark. Photo © Jeremy Stafford-Deitsch

Blue Shark

 

14a) Gill slits long, extending almost full height of head; teeth minute and hooked

Basking shark (Cetorhinus maximus) underwater. Photo © Dan Burton

Basking Shark

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

White sharks feed on the Pacific angelshark. Photo © Jeremy Stafford-Deitsch

White Shark

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

Shortfin Mako. Photo © Jeremy Stafford-Deitsch

Shortfin Mako

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

Longfin mako. Photo courtesy National Marine Fisheries Service

Longfin Mako

 

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

Bonnethead. Photo courtesy Virginia Institute of Marine Science

Bonnethead

18b) Head hammer-shaped Question 19

 

19a) Head margin broadly convex without a noticeable indentation at tip of snout

Smooth hammerhead. Photo © George Burgess

Smooth Hammerhead

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

Near-term scalloped hammerhead embryo, dorsal and ventral view. Photo © FLMNH

Scalloped Hammerhead

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

Great hammerhead in the Bahamas. Photo © Jeremy Stafford-Deitsch

Great Hammerhead

 

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

Bigeye thresher. Photo © George Burgess

Bigeye Thresher

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

Thresher shark. Photo courtesy NOAA

Thresher

 

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

Narrowfin smoothhound (Mustelus norrisi) specimen. Photo © George Burgess

Narrowfin Smoothhound

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

Smooth dogfish with gray coloration along the body and a white underside. Photo © George Burgess

Smooth Dogfish

 

26a) Head pointed; large pointed and recurved teeth protrude from mouth

A pair of sand tiger sharks. Image © Doug Perrine

Sand Tiger Shark

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

Nurse Shark

Nurse Shark

27b) No barbel on margin of each nostril; precaudal pit present; teeth erect with serrations on larger individuals, smooth on young

A lemon shark with two bull sharks in background - all predators of the nurse shark. Photo © Klaus Jost

Lemon Shark

 

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

Oceanic whitetip shark (Carcharhinus longimanus) underwater. Photo © Doug Perrine

Oceanic Whitetip Shark

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

Atlantic sharpnose shark: A) head, B) ventral view of mouth and snout. Image © George Burgess

Atlantic Sharpnose Shark

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

Silky shark (Carcharhinus falciformis) specimen. Photo © George Burgess

Silky Shark

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 37

 

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

Night Shark. Photo © George Burgess

Night Shark

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

Sandbar sharks lives in shallow coastal waters. Photo © Doug Perrine

Sandbar Shark

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

Bignose Shark. Photo © H.W. Pratt

Bignose Shark

 

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

Caribbean reef shark: predator of the great barracuda. Photo © David Snyder

Caribbean Reef Shark

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

Galapagos shark (Carcharhinus galapagensis) underwater. Photo © Doug Perrine

Galapagos Shark

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

Dusky shark caught on a commercial longline set. Photo © George Burgess

Dusky Shark

 

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 Bullshark Bull Shark
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

Juvenile blacknose shark showing the distinctive black spot under the tip of the snout. Photo © George Burgess

Blacknose Shark

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

Finetooth Shark. Photo © George Burgess

Finetooth Shark

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

Spinner shark. Photo © George Burgess

Spinner Shark

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

Blacktip reef shark. Photo © Pasquale Pascullo

Blacktip Shark