Description
E. japonica is a very large, robust baleen whale. It very closely resembles the other right whale species—the North Atlantic right whale (E. glacialis) and the southern right whale (E. australis). Indeed, without knowing which ocean an individual came from, the physical similarities are so extensive that individuals can only be identified to species by genetic analysis. Relative to the other right whale species, E. japonica may be slightly larger. Like other baleen whales, female North Pacific right whales are larger than males. Also, North Pacific brindle-colored individuals are less common than they are among southern right whales.
E. japonica is easily distinguished in the wild from other whale species in the North Pacific. North Pacific Right whales are very large and can reach from 15 to 18.3 m (49 to 60.0 ft) in length as adults, larger than the North Atlantic Right Whale. Typical body mass is from 50,000–80,000 kg (110,000–180,000 lb). There is one record of a 19.8 m (65 ft) whale. They are much larger than gray or humpback whales. Right whales are also very stout, particularly when compared to the other large baleen whales such as blue and fin whales. For 10 North Pacific right whales taken in the 1960s, their girth in front of the flippers was 0.73 of the total length of the whale.
Right whales are the only baleen whale species in the North Pacific that lack a dorsal fin altogether. Right whales are also unique in that all individuals have callosities—roughened patches of epidermis covered with aggregations of hundreds of small cyamids that cluster on the callosities. As in other species of right whales, the callosities appear on its head immediately behind the blowholes, along the rostrum to the tip which often has a large callosity, referred to by whalers as the "bonnet".
The species most similar to the North Pacific right whale in the North Pacific/Bering Sea area is the closely related bowhead whale. Both species have huge heads that constitute up to one-third of the body length, highly arched mouths, very long, fine baleen, no dorsal fin, and great breadth. However, the seasonal ranges of the two species do not overlap. The bowhead whale is found at the edge of the pack ice in more Arctic waters in the Chuckchi Sea and Beaufort Sea, and occurs in the Bering Sea only during winter. The bowhead whale is not found in the North Pacific. Bowhead whales completely lack callosities, the easiest way to distinguish the two species.
Although more than 15,000 right whales were killed by whalers in the North Pacific, there are remarkably few detailed descriptions of these whales. Most of our information about the anatomy and morphology of E. japonica comes from 13 whales killed by Japanese whalers in the 1960s and 10 whales killed by Russian whalers in the 1950s. Basic information about right whale lengths and sex are also available from coastal whaling operations in the early part of the 20th century.
Read more about this topic: North Pacific Right Whale
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