Maximum size is less than that of fin and blue whales. Dorsal fin is decidedly taller, more falcate, and located farther forward (a little more than one-third the body length forward from the fluke notch) than in other large baleen whales. Differs from the Bryde's whale in having a taller, less sharply pointed dorsal fin and a single dorsal rostral ridge rather than three ridges. Differs from the fin whale in the more upward-angled dorsal fin (located farther forward on the body), the lack of asymmetrical lower lip coloration, lack of whitish dorsal chevrons, lack of mixed color baleen, and fewer throat grooves (32-60 vs. 56-100); dorsal fin of sei whale tends to surface simultaneously with the head, rather than later as in the fin whale. Differs from the blue whale in the less U-shaped snout and much larger and more anterior dorsal fin. (Leatherwood and Reeves 1983).