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The bowhead whale (Balaena mysticetus) is a species of baleen whale belonging to the family Balaenidae and is the only living representative of the genus Balaena. It is the only baleen whale endemic to the Arctic and subarctic waters, and is named after its characteristic massive triangular skull, which it uses to break through Arctic ice. Other common names of the species included the Greenland right whale, Arctic whale, steeple-top, and polar whale. Bowheads have the largest mouth of any animal representing almost one-third of the length of the body, the longest baleen plates with a maximum length of 4 metres (13 feet), and may be the longest-lived mammals, with the ability to reach an age of more than 200 years. The bowhead was an early whaling target. Their population was severely reduced before a 1966 moratorium was passed to protect the species. Of the five stocks of bowhead populations, three are listed as "endangered", one as "vulnerable", and one as "lower risk, conservation dependent" according to the IUCN Red List. The global population is assessed as of least concern. Taxonomy Carl Linnaeus named this species in the tenth edition of his Systema Naturae (1758). It was seemingly identical to its relatives in the North Atlantic, North Pacific, and Southern Oceans, and as such they were all thought to be a single species, collectively known as the "right whale", and given the binomial name Balaena mysticetus. Today, the bowhead whale occupies a monotypic genus, separate from the right whales, as proposed by the work of John Edward Gray in 1821. For the next 180 years, the family Balaenidae was the subject of great taxonometric debate. Authorities have repeatedly recategorized the three populations of right whale plus the bowhead whale, as one, two, three or four species, either in a single genus or in two separate genera. Eventually, it was recognized that bowheads and right whales were different, but there was still no strong consensus as to whether they shared a single genus or two. As recently as 1998, Dale Rice listed just two species – B. glacialis (the right whales) and B. mysticetus (the bowheads) – in his comprehensive and otherwise authoritative classification. Studies in the 2000s finally provided clear evidence that the three living right whale species comprise a phylogenetic lineage, distinct from the bowhead, and that the bowhead and the right whales are rightly classified into two separate genera. The right whales were thus confirmed to be in a separate genus, Eubalaena. The relationship is shown in the cladogram below: The earlier fossil record shows no related cetacean after Morenocetus, found in a South American deposit dating back 23 million years. An unknown species of right whale, the so-called "Swedenborg whale", which was proposed by Emanuel Swedenborg in the 18th century, was once thought to be a North Atlantic right whale. Based on later DNA analysis, those fossil bones claimed to be from Swedenborg whales were confirmed to be from bowhead whales. Description The bowhead whale has a large, robust, dark-coloured body and a white chin. It has a massive triangular skull, which it uses to break through the Arctic ice to breathe. Inuit hunters have reported bowheads surfacing through 60 cm (24 in) of ice. It also possesses a strongly bowed lower jaw and a narrow upper jaw. Its baleen is the longest of that of any whale, at 3 m (10 ft), and is used to strain tiny prey from the water. The bowhead whale has paired blowholes at the highest point of the head, which can spout a blow 6.1 m (20 ft 0 in) high. The bowhead's blubber is the thickest of any animal's, with a maximum of 43–50 cm (17–19+1⁄2 in). Unlike most cetaceans, the bowhead does not have a dorsal fin—an adaptation for spending much time under sea-surface ice. Like the sperm whale and other cetaceans, the bowhead whale has a vestigial pelvis that is not connected to the spine. Bowhead whales are comparable in size to the three species of right whales. According to whaling captain William Scoresby Jr., the longest bowhead he measured was 17.7 m (58 ft 1 in) long, while the longest measurement he had ever heard of was of a 20.4 m (66 ft 11 in) whale caught at Godhavn, Greenland, in early 1813. He also spoke of one, caught near Spitsbergen around 1800, that was allegedly nearly 21.3 m (69 ft 11 in) long. In 1850, an American vessel claimed to have caught a 24.54 m (80 ft 6 in) individual in the Western Arctic. Whether these lengths were actually measured is questionable. The longest reliably measured were a male of 16.2 m (53 ft 2 in) and a female of 18 m (59 ft), both landed in Alaska. On average, female bowheads are larger than males. The adults would have likely measured 19 metres (62 ft) in length and 80 metric tons (88 short tons) in body mass, but larger individuals (like the one claimed in 1850) may weigh up to 100 metric tons (110 short tons). Analysis of hundreds of DNA samples from living whales and from baleen used in vessels, toys, and housing material has shown that Arctic bowhead whales have lost a significant portion of their genetic diversity in the past 500 years. Bowheads originally crossed ice-covered inlets and straits to exchange genes between Atlantic and Pacific populations. This conclusion was derived from analyzing maternal lineage using mitochondrial DNA. Whaling and climatic cooling during the Little Ice Age, from the 16th century to the 19th, is supposed to have reduced the whales' summer habitats, which explains the loss of genetic diversity. A 2013 discovery has clarified the function of the bowhead's large palatal retial organ. The bulbous ridge of highly vascularized tissue, the corpus cavernosum maxillaris, extends along the centre of the hard plate, forming two large lobes at the rostral palate. The tissue is histologically similar to that of the corpus cavernosum of the mammalian penis. This organ is thought to provide a mechanism of cooling for the whale (which is normally protected from the cold Arctic waters by 40 cm or 16 in or more of fat). During physical exertion, the whale must cool itself to prevent hyperthermia (and ultimately brain damage). This organ becomes engorged with blood, and as the whale opens its mouth cold seawater flows over the organ, thus cooling the blood. Behaviour Swimming The bowhead whale is not a social animal, typically travelling alone or in small pods of up to six. It is able to dive and remain submerged under water for up to an hour. The time spent under water in a single dive is usually limited to 9–18 minutes. The bowhead is not thought to be a deep diver, but can reach a depth down to 150 m (500 ft). It is a slow swimmer, normally travelling around 2–5 km/h (1–3 mph) [0.55–1.39 m/s]. When fleeing from danger, it can travel at a speed of 10 km/h (6.2 mph) [2.78 m/s (9 ft/s)]. During periods of feeding, the average swim speed is increased to 1.1–2.5 m/s (4.0–9.0 km/h). Feeding The head of the bowhead.... Discover the Gary W Miller popular books. Find the top 100 most popular Gary W Miller books.