The Bowhead Whale is a baleen whale of the right whale family Balaenidae in suborder Mysticeti. A stocky dark-colored whale without a dorsal fin, it can grow to 20 m (66 ft) in length. This thick-bodied species can weigh 75 tonnes (74 long tons; 83 short tons) to 100 tonnes (98 long tons; 110 short tons), second only to the blue whale, although the bowhead's maximum length is less than several other whales. It lives entirely in fertile Arctic and sub-Arctic waters, unlike other whales that migrate to feed or reproduce to low latitude waters. It is also known as Green land right whale or Arctic whale. American whalemen called it the steeple-top, polar whale, or Russia or Russian wahle. The bowhead is perhaps the longest-living mammal, and has the largest mouth of any animal.
The bowhead was an early whaling target. Its population was severely reduced before a 1966 moratorium. The population is estimated to be over 24,900 worldwide, down from an estimated 50,000 before whaling.
The bowhead whale has a robust, dark-colored body, no dorsal fin and a strongly bowed lower jaw and narrow upper jaw. Its baleen, the longest of any whale at 3 m (9.8 ft), strains tiny prey from the water. The whale has a massive bony skull which it uses to break through the Arctic ice to breathe. Inuit hunters have reported them surfacing through 60 cm (24 in) of ice. The bowhead may grow up to 14–18 m (46–59 ft) and weigh from 30,000 to 60,000 kg (66,000 to 130,000 lb) in adulthood. It is of comparable size to the three species of right whale. The largest bowhead yet reported was 21.2 m (70 ft) for a giant caught off Spitsbergen, Norway. This specimen was later estimated to have weighed approximately 133 t (290,000 lb). Females are larger than males. Its blubber is the thickest of any animal, averaging 43–50 cm (17–20 in).
The bowhead whale is the only baleen whale to spend its entire life in and around Arctic waters. The Alaskan population spends the winter months in the southwestern Bering Sea. The group migrates northward in the spring, following openings in the pack ice, into the Chukchi and Beaufort Seas.
Unlike most other baleen whales, which primarily feed on concentrated shoals of prey species, it feeds in a manner similar to the basking shark by swimming forward with its mouth wide open, continuously filtering water through its baleen plates. Thus, it specializes in much smaller prey, such as copepods. Its mouth has a large upturning lip on the lower jaw that helps to reinforce and contain the baleen plates within its mouth, and prevents buckling or breakage of the plates due to the pressure of the water passing through them as it advances.
This is in contrast to the rorquals, which have distendable ventral pleats that they fill with prey-laden water, then expel the water while filtering out the prey through their baleen plates.