is a family
of mysticete whales
that contains two living genera. Commonly called the right whales as it contains mainly right whale
species. This name can be confusing, however, since one of the species is the Bowhead Whale
, which is different from the right whales
Balaenids are large whales, with an average adult length of 15 to 17 metres (45-50 feet), and weighing 50-80 tonnes. Their principle distinguishing feature is their narrow, arched, upper jaw, which gives the animals a deeply curved jawline. This shape allows for especially long baleen
plates. The animals utilise these by floating at or near the surface, and straining food from the water, which they then scrape off the baleen with their tongues - a feeding method that contrasts with those of the rorquals
and the Gray Whale
. Their diet consists of small crustaceans
, primarily copepods
, although some species also eat a significant amount of krill
Balaenids are also robustly built by comparison with the rorquals, and lack the grooves along the throat that are distinctive of those animals. They have exceptionally large heads in comparison with their bodies, reaching 40% of the total length in the case of the Bowhead Whale. They have short, broad, flippers, and lack a dorsal fin.
All species are at least somewhat migratory, moving into warmer waters during the winter, during which they both mate and give birth. Gestation lasts 10-11 months, results in the birth of a single young, and typically occurs once every three years.