The baleen whales are usually divided into 3 families:

---The Right Whales (Balaenidae)

Picture: Bowhead Whale.

These are bulky, slow moving whales without a dorsal fin. They have a strongly curved large mouth and large baleen plates. To this group belong the Northern and Southern right whales, the bowhead whale and the pygmy right whale. The pygmy right whale is small and has a small dorsal fin. It is sometime put in a family of its own, the Neobalaenidae.

---The Fin Whales or Rorquals (Balaenopteridae)

These are large, relatively slender whales, with a straight mouth and relatively short baleen plates. They have obvious grooves on the throat, which makes it possible to scoop up large amounts of water with food and then push it out through the baleen plates. This family includes the blue whale, the fin whale, the Bryde's whale, the sei whale and the humpback whale.

---Gray Whales (Eschrichtiidae)

These whales have no dorsal fin, but have a number of small humps on the back, a slightly curved mouth with short baleen plates. This family includes only one species: the gray whale.

---Distribution

Baleen whales can be found in all oceans and seas, from the Arctic, through the tropics, all the way to the Antarctic. However, some species are restricted to only some areas. See the species descriptions for more details.

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---Appearance

The Giants of the Seas

Baleen whales are truly the giants of the seas. The actual maximum size varies per species. The largest species, and actually the largest animal that ever roamed the earth, is the blue whale, which can grow to a length of more that 30 m. and weigh more than 100.000 kg. The smallest baleen whale is the pygmy right whale, which grows to "only" 6 m. and 4,500 kg.

In many mammal species, males are larger than females. In baleen whales however, the female is usually larger than the male. For baleen whales, their size is important. First of all, it gives them an edge against predators, although killer whales do occasionally attack even adult blue whales.

In addition, the large size, combined with their general rounded physique, gives them a a better opportunity to maintain their body temperature: the ratio between body surface area and body volume is smaller so the heat loss is (relatively) less than in smaller animals.
Also, the large body gives them a large fat storage, which means they can go without food for extended periods of time. The fat or blubber layer in larger whales can be quite thick. In the right whales, the blubber accounts for 36-46% of the total body weight.

Although baleen whales are enormous animals, it does not mean they are clumsy animals. On the contrary, most baleen whale species are graceful swimmers and can make impressive jumps.

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