Aerial photograph of North Atlantic right whale and calf. Photo courtesy of New England Aquarium

Right whales are located in all oceans of the world, and are found in the temperate to subpolar latitudes (between 20° and 60° in both hemispheres). These whales received their name from whalers, which considered them the "right" whale to hunt. They were good to hunt because they swim rather close to shore, float when dead, and produce a large amount of oil when harvested. Today the North Atlantic (Eubalaena glacialis) and North Pacific (Eubalaena japonica) right whales are among the most endangered of the large whales.

Right whales are typically 13-16 m (42-52 ft) in length. Right whales have an extremely large head and a body that is very rounded. Their width is often more than half of their body length. Most of the body is black. These whales have no dorsal fin. Their pectoral flippers are large and broad. The feature that stands out most on right whales is callosities on the head region. Callosities are hardened patches of chitin, the same material found in human fingernails. Callosities provide a home for large numbers of tiny crustaceans called "whale lice." Researchers are able to identify individual right whales by their callosity patterns or scars on their body and tail.

Right whale vocalizations are mostly concentrated in the lower frequencies. Moans, groans, belches, and pulses have most of their acoustic energy below 500 Hz. Some vocalizations will occasionally reach up to 4 kHz. Right whales use a variety of calls when socializing in a group. In the North Atlantic, calls lasting 0.5-2.8 seconds long, ranging in frequency from 400 to 3200 Hz, are believed to be produced by the focal female in a surface active group to attract males. Male North Atlantic right whales produce gunshot-like sounds that might function as a threat display to other males.