168 



KEY TO MARINE MAMMALS (Cont.) 



17 Throat and belly smooth, without longitudinal grooves; no dorsal 



fin. (RIGHT WHALES) 18 



17' Longitudinal grooves present on belly and throat, or only on throat 

 (Fig. 27); fin or at least a bumpy ridge present on back. 



(GRAY WHALES) 19 



18 Skull narrow and long, a regular semicircular arch; head about one- 

 third of total body length; mouth slit arch-shaped; upper margin 



of lower lip bordered by a smooth curved line, without scallop like 

 outgrowths; no outgrowth on upper side of snout, between its tip and 

 the blowhole; average number of baleen plates 330 per side, length 

 in the middle of the jaw up to 3.5 m, black in color. BOWHEAD 



18' Skull narrow and long, an arch with the posterior region noticeably 

 steeper than the anterior; head about one-fourth the total length; 

 mouth slit S-shaped; upper margin of lower lip scalloped; a thick 

 outgrowth (bonnet, see Fig. 27) on top of snout between its tip and 

 the blowhole; average number of baleen plates 250 per side, length 

 up to 2 m, usually black in color. NORTHERN RIGHT WHALE 



19 Two to four longitudinal grooves on throat, slightly diverging 

 posteriorly; no dorsal fin but only a low hump on the back, followed 

 by a ridge of bumps extending nearly to the flukes; about 180 baleen 

 plates per side, each plate yellowish, up to 20-40 cm in length, and 

 with coarse bristles; baleen on left and right sides do not meet in 

 front; outer edges of baleen rounded; body color, mottled gray even 



in young. CALIFORNIA GRAY WHALE 



19' More than 11-12 parallel grooves on the belly and throat (count 

 grooves between flippers; do not include grooves on sides above 

 flippers, or on side of head); dorsal fin well developed; more 

 than 220 baleen plates per side, connected in front of jaw by 

 shaft-like formations; outer edges of baleen sharp. 



(RORQUALS) 20 



20 Flippers very long and with scalloped rear edges, greater than one- 

 fourth the animal's total length; longitudinal grooves on belly and 

 throat deep and broad (8-10 cm), totalling less than 40 (usually 

 12-36); dorsal fin relatively low and thick, usually increasing in 

 size toward the rear in a step-like configuration; numerous knobs, 

 resembling orange (the fruit) halves in size and shape, on head and 

 lower jaws; baleen short, less than 61 cm long, blackish to olive 

 brown, with 10-35 grayish white bristles per cm, 270-400 plates per 

 side. HUMPBACK WHALE 



