Remarkably for their large size, North Atlantic right whales feed only on tiny planktonic prey, including large copepods, the size of a grain of rice; krill, a shrimp-like crustacean; tiny planktonic snails and the drifting larval stages of barnacles and other crustaceans (2). North Atlantic right whales are ‘skim feeders’, which feed by swimming forward with their mouth open, allowing water to flow into the mouth and out through the baleen (2). Tiny prey is strained from the water as it becomes caught in the fringed baleen, where it is then dislodged by the tongue and swallowed (5). Although they often feed at the ocean surface, or just below, the North Atlantic right whale is also believed to feed close to the bottom, as it has been seen surfacing after a 10 to 20 minute dive with mud on its head (2).
After feeding at northern latitudes during the summer, the North Atlantic right whale migrates south for winter. Pregnant females head for the inshore calving grounds, whilst the location of the remaining majority of the population is not known. Wherever they head, this is the time at which mating takes place (2). North Atlantic right whale females typically first calve at nine to ten years of age, and then give birth to a single young every three years. The gestation period lasts for about one year, and following birth, the mother and her young remain close until the calf is weaned at the age of one (2). During its first year of life the calf learns the location of critical feeding grounds from its mother, which it will continue to visit for the remainder of its life. The female then takes a third year to replenish her energy stores before breeding again (2).
Today, the North Atlantic right whale is a rarely seen animal, but its name refers to a time when they were more frequently observed, when they swam slowly, close to shore, thus making them an easy target for whalers. Not only did this swimming behaviour make this whale the ‘right’ one to hunt, but it also floated when dead and yielded vast quantities of valuable oil and baleen (2). Despite its bulky size, the North Atlantic right whale is able to perform acrobatic acts such as jumping out of the water, known as breaching, violently slapping the water surface with the tail and slapping the surface with a pectoral fin (2). Although the purpose of these behaviours is not fully understood, they may be used in communication. Similarly, the range of low frequency groans, moans and belches that the North Atlantic right whale makes are hypothesized to be used to communicate with other individuals, or signal aggression (2).