Balaenoptera borealis

Scientific Name:-
Balaenoptera borealis

Common Name:-
Sei whale

Malayalam Name:-
Sei Thimingalam


Classified as "Endangered” by the IUCN. Northern Hemisphere populations are listed as CITES Appendix II, indicating they are not immediately threatened with extinction, but may become so if they are not listed. Populations in the Southern Hemisphere are listed as CITES Appendix I, indicating they are threatened with extinction if trade is not halted. Listed in Appendix I and Appendix II of the Convention on the Conservation of Migratory Species of Wild Animals (CMS). Listed in Schedule II of Indian (Wildlife) Protection Act.


The body of the Sei Whale is slim and streamlined. The narrow head is slightly arched, with a single prominent ridge from the blowholes to the tip of the snout. A few hairs are present on both jaws and the snout. They often look similar in appearance to Bryde's whales, but can be distinguished by the presence of a single ridge located on the animal's "rostrum". Bryde's whales, unlike other rorquals, have three distinct prominent longitudinal ridges on their rostrum. Sei whales have 219-410 baleen plates that are dark in color with gray/white fine inner fringes in their enormous mouths. They also have 30-65 relatively short ventral pleats that extend from below the mouth to the naval area. The number of throat grooves and baleen plates may differ depending on geographic population. The flippers are relatively small, about one-eleventh the body length, and pointed. The tail flukes are relatively small. The dorsal fin is 25 to 60 cm tall, hooked and placed slightly less than two-thirds along the back. The Sei Whale is dark grey on the back and sides, marked with light-coloured scars. These scars may give its body a metallic look. The animal is pale below. A region of the belly is greyish white. These large animals can reach lengths of about 40-60 ft (12-18 m) and weigh 45,000 kg. At sea, large, sloping dorsal fin; narrow head with single prominent ridge. The whale's name comes from the Norwegian word for pollock, a fish that appears off the coast of Norway at the same time of the year as the sei whale. Sei whales usually travel alone or in pods of up to six individuals. This species is a filter feeder, using its baleen plates to obtain its food by opening its mouth, engulfing or skimming large amounts of the water containing the food, then straining the water out through the baleen, trapping any food items inside its mouth.


There are several records of the Sei Whale in India. These include dead specimens washed ashore and live animals caught in fishing nets.


Noble & Nasser, 1992 A 9m long specimen stranded near Cochin, landed at Puthuvypu, Vypeen Island.


Sei whales have a cosmopolitan distribution and prefer subtropical to subpolar waters on the continental shelf edge and slope worldwide. They are usually observed in deeper waters of oceanic areas far from the coastline. The sei whale migrates annually from cool and subpolar waters in summer to winter in temperate and subtropical waters. It is the third-largest rorqual after the blue whale and the fin whale.


Balaena musculus Linnaeus, 1758; Balaenoptera jubartes Lacépède, 1804; Balaena borealis Fischer, 1829; Rorqualus boops F. Cuvier, 1836; Rorqualus borealis Hamilton, 1837; Physalus sibbaldii Gray, 1847; Balaenoptera gigas Reinhardt, 1857; Pterobalaena gigas Reinhardt, 1857; Balaenoptera indica Blyth, 1859; Sibbaldius borealis Gray, 1864; Physalus latirostris Flower, 1865; Sibbaldius antarcticus Burmeister, 1866; Rorqualus major Knox, 1870; Balaenoptera carolinae Malm, 1866; Rorqualus major Knox, 1870; Balaenoptera sibbaldii Flower, 1885; Pterobalaena grypus Munter, 1877; Balaenoptera sibbaldi Van Beneden, 1887; Balaenoptera miramaris Lahille, 1898; Sibbaldius musculus Kellogg, 1929


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