SEI WHALE (B)
Balaenoptera borealis Lesson 1828
Other Common Names
Pollack whale, sardine whale, Rudolphi's rorqual.
Description
Sei (pronounced "say") whales have been reported to reach 62 feet (19 m).
The snout is less acutely pointed than that of the fin whale but when viewed from the side appears slightly arched. In general, the head is intermediate in shape between that of the blue whale and that of the fin whale. The dorsal fin, which is from 10 to 24 inches (25.4 to 61 cm) tall and strongly falcate in adult animals, is located about two-thirds of the way back on the back, farther forward than that of the blue or fin whales. Sei whales are dark steel gray on the back and sides, and on the posterior portion of the ventral surface. The body often has a galvanized appearance due to scars possibly resulting from lamprey bites inflicted during migrations into warmer waters. These scars may be dark gray to almost white in color. On the belly there is a region of grayish white that is confined to the area of the ventral grooves. Neither the flippers nor the tail flukes are white underneath. The right lower lip and the mouth cavity, unlike those of the fin whale, are uniformly gray. The baleen plates are uniformly grayish black with fine grayish-white fringes. (A small number of sei whales have been noted to have a few half-white plates near the front of the mouth, a feature which might result in their confusion with fin whales.)
Natural History Notes
The blow of sei whales is an inverted cone rarely taller than 15 feet (4.6 m).