Right whales are three species of large baleen whales of the genus Eubalaena: the North Atlantic right whale (E. glacialis), the North Pacific right whale (E. japonica) and the southern right whale (E. australis). They are classified in the family Balaenidae with the bowhead whale. Right whales have rotund bodies with arching rostrums, V-shaped blowholes and dark gray or black skin. The most distinguishing feature of a right whale is the rough patches of skin on its head, which appear white due to parasitism by whale lice. Right whales are typically 13–17 m (43–56 ft) long and weigh up to 100 short tons (91 t; 89 long tons) or more. All three species are migratory, moving seasonally to feed or give birth. The warm equatorial waters form a barrier that isolates the northern and southern species from one another although the southern species, at least, has been known to cross the equator. In the Northern Hemisphere, right whales tend to avoid open waters and stay close to peninsulas and bays and on continental shelves, as these areas offer greater shelter and an abundance of their preferred foods. In the Southern Hemisphere, right whales feed far offshore in summer, but a large portion of the population occur in near-shore waters in winter. Right whales feed mainly on copepods but also consume krill and pteropods. They may forage the surface, underwater or even the ocean bottom. During courtship, males gather into large groups to compete for a single female, suggesting that sperm competition is an important factor in mating behavior. Gestation tends to last a year, and calves are weaned at eight months old. Right whales were a preferred target for whalers because of their docile nature, their slow surface-skimming feeding behaviors, their tendency to stay close to the coast, and their high blubber content (which makes them float when they are killed and which produced high yields of whale oil). Although the whales no longer face pressure from commercial whaling, humans remain by far the greatest threat to these species: the two leading causes of death are being struck by ships and entanglement in fishing gear. Today, the North Atlantic and North Pacific right whales are among the most endangered whales in the world.
Naming A common explanation for the name right whales is that they were regarded as the right ones to hunt, as they float when killed and often swim within sight of shore. They are quite docile and do not tend to shy away from approaching boats. As a result, they were hunted nearly to extinction during the active years of the whaling industry. However, this origin is questionable: in his history of American whaling, Eric Jay Dolin writes:
Despite this highly plausible rationale, nobody actually knows how the right whale got its name. The earliest references to the right whale offer no indication why it was called that, and some who have studied the issue point out that the word "right" in this context might just as likely be intended "to connote 'true' or 'proper,' meaning typical of the group." For the scientific names, the generic name Eubalaena means "good or true whales", and specific names include glacialis ("ice") for North Atlantic species, australis ("southern") for Southern Hemisphere species, and japonica ("Japanese") for North Pacific species.
Taxonomy
The right whales were first classified in the genus Balaena in 1758 by Carl Linnaeus, who at the time considered all of the right whales (including the bowhead) as a single species. Through the 19th and 20th centuries, in fact, the family Balaenidae has been 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. In the early whaling days, they were all thought to be a single species: Balaena mysticetus. Eventually, it was recognized that bowheads and right whales were in fact different, and John Edward Gray proposed the genus Eubalaena for the right whale in 1864. Later, morphological factors such as differences in the skull shape of northern and southern right whales indicated at least two species of right whale – one in the Northern Hemisphere, the other in the Southern Ocean. As recently as 1998, Rice, in his comprehensive and otherwise authoritative classification listed just two species: Balaena glacialis (the right whales) and Balaena mysticetus (the bowheads).
In 2000, two studies of DNA samples from each of the whale populations concluded that the northern and southern populations of right whale should be considered separate species. What some scientists found more surprising was the discovery that the North Pacific and North Atlantic populations are also distinct, and that the North Pacific species is more closely related to the southern right whale than to the North Atlantic right whale. The authors of one of these studies concluded that these species have not interbred for between 3 million and 12 million years. In 2001, Brownell et al. reevaluated the conservation status of the North Pacific right whale as a distinct species, and in 2002, the Scientific Committee of the International Whaling Commission (IWC) accepted Rosenbaum's findings, and recommended that the Eubalaena nomenclature be retained for this genus. A 2007 study by Churchill provided further evidence to conclude that the three different living right whale species constitute a distinct phylogenetic lineage from the bowhead, and properly belong to a separate genus. The following cladogram of the family Balaenidae serves to illustrate the current scientific consensus as to the relationships between the three right whales and the bowhead whale.
A cladogram is a tool for visualizing and comparing the evolutionary relationships between taxa; the point where each node branches is analogous to an evolutionary branching – the diagram can be read left-to-right, much like a timeline.
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