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 1.5-25 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 knobbed on leading edge; less than 22 



broad and conspicuous ventral grooves, longest extending at least to navel; head covered with 

 numerous knobs; 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 knobs; from 40 to 100 fine ventral grooves, longest 



extending at least to navel; head lacks knobs 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,^ 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 massive, 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 1 1 



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 bottle- 

 nosed 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 



'Blue whale has faint lateral ridges. 



165 



