North Pacific right whales are massive creatures with heads that can be almost one-third of their total body length. Males are generally measure between 14 and 17 m in length, and females are longer than males. Adults weigh between 70 and 100 tons. Newborn right whales are generally 4 to 6 m long. The skin of north Pacific right whales is largely black, although individuals may have white patches on their undersides. They are marked by large callosities, large patches of raised tissue, on the rostrum, near the blowholes and eyes, and on the chin and lower lip. The largest callosity, on the top of the rostrum, is referred to as a "bonnet." These callosities harbor barnacles (Cirripedia) and whale lice (Cyamidae), which make the callosities appear white, yellow, or pink. Callosities emerge after birth, but a pattern of callosities is not established for 7 to 10 months. Callosities may grow upwards and even break off, but their placement on a whale's head generally does not change.
North Pacific right whales are stocky baleen whales with broad rounded flippers, no dorsal fin or ridge, and lacking a grooved throat. The tail of a right whale is all black, broad, and is deeply notched in the center with a smooth trailing edge. Their flippers are broad and fan-shaped. Right whales are slow swimmers, only achieving speeds up to 5 knots (just over 9 km/hr) and averaging 2 knots (3.7 km/hr). Their head and jaws are massive, making up almost 1/3 of the length of these whales. Baleen plates are brownish-gray in color, range from 200 to 270 in number on each side of the mouth, and can reach 3 m in length. Their blowholes are separated on their dorsal surface and exhalations result in a large, V-shaped blows up to 5 m high. Their 7 cervical vertebrae are fused into a single unit. These whales got their name for being the "right" whales to catch. Once killed, their large amounts of blubber cause them to float at the surface and result in huge yields of oil. Their blubber can be up to 71 cm thick and make up to 45% of their body mass.
North Pacific right whales may be confused with bowhead whales, but are distinguishable by the presence of callosities on their body and white patches on their undersides. They are also closely related to southern right whales, though north Pacific right whales have larger and wider flippers than their southern counterparts. North Pacific right whales were, until recently, considered the same species as north Atlantic right whales. The species were separated because of genetic evidence
Range mass: 63,500 to 72,574 kg.
Average mass: 90,718 kg.
Range length: 13.7 to 17 m.
Average length: 15 m.
Sexual Dimorphism: female larger