Scientists divide baleen whales into three groups. These groups are: (1) right whales; (2) gray whales; and (3) rorquals.
Right whales
have a thick, solid body and a huge head. The head of most right whales makes up about a third of the total body length. Right whales swim slowly, averaging about 3 miles (4.8 kilometers) per hour. They feed by swimming into a mass of plankton with their mouths open. Water flows through the baleen, and plankton becomes entangled in the baleen fibers. There are three main kinds: (1) bowhead whales; (2) black right whales; and (3) pygmy right whales.
Gray whales
live in the North Pacific Ocean. Their skin is gray, with white blotches, some of which are shellfish called barnacles. Gray whales have a series of low humps on the lower back. The animals may measure up to 43 feet (13 meters) long. Gray whales eat small animals that live on the sandy ocean bottom. The whales suck up sand and mud and use their coarse, relatively short baleen to strain out the animals. They also feed on plankton and small fish.
Rorquals
are baleen whales that have long grooves on the throat and chest. These grooves may number from 10 to 100 and are 1 to 2 inches (2.5 to 5 centimeters) deep. They enable a rorqual to open its mouth extremely wide and gulp enormous quantities of food and water. Rorquals lunge quickly forward into their prey. As the whale closes its mouth, its tongue forces the water out of the mouth through the baleen. The food becomes trapped inside the baleen and is swallowed.
All rorquals have a dorsal, or back, fin, and so are sometimes called finback whales. Most have a long, streamlined shape and can swim faster than other whales.
