The baleen whales, also called whalebone whales or great whales, form the Mysticeti, one of two suborders of the Cetacea (whales, dolphins, and porpoises). Baleen whales are characterized by having baleen plates for filtering food from water, rather than having teeth. This distinguishes them from the other suborder of cetaceans, the toothed whales or Odontoceti. Living species of Mysticeti have teeth only during the embryonal phase. Fossil Mysticeti had teeth before baleen evolved.
The suborder contains four extant families and 15 species.
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 can grow up to 18 m (59 ft) long and weigh up to 100 short tons (91 t; 89 long tons), significantly larger than humpbacks or grays, but smaller than blues.
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 anther. 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 on the ocean bottom. During courtship, males gather into large groups to compete for a single female, suggesting that sperm competition appears to be an important factor in mating behavior. Although the blue whale is the largest animal on the planet, the testes of the right whale are actually ten times larger than those of the blue whale – with each weighing up to 525 kilograms (1,160 lb), they are by far the largest of any animal on Earth. Gestation tends to last a year, and calves are born at 1 short ton (0.91 t; 0.89 long ton) in weight and 4–6 m (13–20 ft) in length. Weaning occurs after eight months.