2. a. Ventral grooves present; dorsal fin present; viewed in profile, upper jaw relatively flat and broad.

(Balaenopterine whale) Go to 3

b. Ventral grooves absent; dorsal fin absent; viewed in profile, upper jaw and lower lips strongly arched; upper jaw very narrow.

(Right whale) Go to 8

3. a. Ventral grooves end before navel.[18] Go to 4

b. Ventral grooves extend to or beyond navel Go to 5

4. a. 50-70 ventral grooves, longest often ending between flippers; baleen less than 8 inches (20.3 cm), mostly white or yellowish white (some posterior plates may be dark) with 15-25 white bristles per centimeter; 300-325 plates per side.

Minke whale, p. 63

b. 38-56 ventral grooves, longest ending well short of navel; baleen less than 31 inches (78.7 cm), black (some anteriormost plates may be white) and with 35-60 fine silky white bristles per centimeter; 318 340 plates per side.

Sei whale, p. 32

5. a. Flippers one-fourth to one-third length of the body length and k.n.o.bbed on leading edge; less than 22 broad and conspicuous ventral grooves, longest extending at least to navel; head covered with numerous k.n.o.bs; baleen less than 24 inches (61 cm), ash black to olive brown (sometimes whitish) with 10-35 grayish white bristles per centimeter; 270-400 plates per side.

Humpback whale, p. 40

b. Flippers less than one-fifth body length; no k.n.o.bs; from 40 to 100 fine ventral grooves, longest extending at least to navel; head lacks k.n.o.bs Go to 6

6. a. Three ridges on head, one from blowholes, forward towards tip of snout, one auxiliary groove along each side of main ridge; 40-50 ventral grooves; 250-300 slate-gray baleen plates with 15-35 dirty gray bristles per centimeter.

Bryde's whale, p. 37

b. Only one prominent ridge on head,[19] from just in front of blowholes forward towards tip of snout; 55-100 ventral grooves Go to 7

7. a. Head broad and U-shaped; dorsal fin less than 13 inches (33 cm) and very far back on tail stock; baleen all black with 10-30 black bristles per centimeter; plates extremely broad relative to length.

Blue whale, p. 19

b. Head broad at gape but sharply pointed on tip; dorsal fin to 24 inches (61 cm) and slightly more than one-third forward from tail; right front one-fifth to one-third of baleen ivory white to yellowish white, remainder dark gray to bluish gray streaked with yellowish white; plates have 10-35 gray or white bristles per centimeter and are narrow relative to length.

Fin whale, p. 26

8. a. Top of snout not covered with callosities; 325-360 baleen plates per side, longest reaching 14 feet (4.3 m); plates black with black bristles (anterior portion of some plates may be whitish).

Bowhead whale, p. 49

b. Top of snout covered with callosities, often including lice and/or barnacles; 250-390 baleen plates per side, longest reaching 7.2 feet (2.2 m); plates dirty or yellowish gray (some anterior plates all or part white and some posterior plates brown or black) with 35-70 bristles per centimeter.

Right whale, p. 52

9. a. Upper part of head extending appreciably past tip of lower jaw; lower jaw markedly undershot and considerably narrower than upper jaw Go to 10

b. Upper part of head not extending appreciably past tip of lower jaw; lower jaw approximately same width as upper jaw Go to 12

10. a. Body more than 13 feet (4.0 m); head ma.s.sive, to one-third of body length; blowhole located far forward of eyes and to left front of head; dorsal fin low, triangular or rounded followed by series of knuckles or crenulations; 18-25 teeth in each lower jaw fit into sockets in upper jaw (10-16 upper teeth rarely emerge).

Sperm whale, p. 57

b. Body less than 13 feet (4.0 m); head considerably less than one-third body length; blowhole located approximately even with eyes on top of head, slightly displaced to left but not on left front of head; conspicuous dorsal fin present; 8-16 teeth in each lower jaw fitting into sockets in upper jaw Go to 11

11. a. No creases on throat; dorsal fin small and located in latter third of back; 12-16 teeth (rarely 10-11) in each lower jaw.

Pygmy sperm whale, p. 144

b. Inconspicuous creases on throat; dorsal fin tall and falcate, resembling that of the Atlantic bottlenosed dolphin, and located near middle of back; 8-11 (rarely 13) extremely sharp teeth in each lower jaw; rarely 1-3 teeth in each upper jaw.

Dwarf sperm whale, p. 148

12. a. Two conspicuous grooves on outer surface of throat forming V-shape pointed forward; notch absent or inconspicuous in flukes.

(Beaked whale) Go to 13

b. No conspicuous grooves on outer surface of throat; deep median notch on rear margin of tail flukes Go to 18

13. a. A pair of teeth located at the tip of the lower jaw (erupted only in adult males, concealed in females and immature animals) Go to 14

b. No teeth at the tip of the lower jaw Go to 16

NOTE: Immature individuals of the species covered in paragraphs 14 and 15 may not be readily identifiable without museum preparation and examination.

14. a. Two well-developed teeth, erupted or hidden beneath the gum, are compressed so they appear elliptical in cross section; body to 16 feet (4.9 m); united portion of the lower jaws[20] more than one-fourth the length of the entire lower jaw.

True's beaked whale, p. 77

b. Two well-developed teeth substantially less flattened so that they appear more nearly rounded in cross section Go to 15

15. a. Distinct elongated beak; p.r.o.nounced bulge to forehead; blowhole located in lateral crease behind bulge; body to 32 feet (9.8 m); sometimes second pair of teeth behind first in lower jaw.

Northern bottlenosed whale, p. 67

b. No distinct beak; forehead slightly concave in front of blowhole, increasing in concavity with increasing size; body to 23 feet (7.0 m); united portion of lower jaw less than one-fourth the length of the entire lower jaw; head of adult males all white.

Goosebeaked whale, p. 70

16. a. A single pair of teeth in the united portion of the lower jaw, at the suture of the mandible (about one-third of the way from the tip of the snout to the gape); length to 22 feet (6.7 m); flukes less than one-fifth the body length.

Antillean beaked whale, p. 78

b. A single pair of teeth back of united portion of lower jaw; body less than 17 feet (5.2 m) Go to 17

17. a. Teeth not exceptionally large and located immediately back of united portion of lower jaw, about half way from the tip of the snout to the gape.

North Sea beaked whale, p. 82

b. Teeth exceptionally large, located on bony prominences near the corner of the mouth, and oriented backwards; corners of mouth, particularly in adult males, have high-arching contour; flukes to one-sixth or one-fifth of the body length.

Dense-beaked whale, p. 80

18. a. Rostrum, if present, not sharply demarcated from forehead Go to 19

b. Head has a distinct, though sometimes short rostrum separated from the forehead by a distinct crease angle Go to 30

19. a. Teeth spade-shaped, laterally compressed and relatively small; body to only about 5 feet (1.5 m); 22-28 teeth in each upper and lower jaw.

Harbor porpoise, p. 150

b. Teeth conical and sharply pointed (in cross section circular, or slightly flattened anteroposteriorly) Go to 20

20. a. No distinct dorsal fin; back marked instead with small dorsal ridge near midpoint of back. Go to 21

b. Distinct dorsal fin, in middle or forward third of the back Go to 22