Whales are the largest animals on the planet. They come from the order Cetacea, an order which also includes the dolphins and porpoises. Under Cetacea there are two sub-orders, the Mysticeti and the Odontoceti. From these two sub-orders, whale species are spread. The sub-order Mysticeti or Baleen Whales refers to whale species without teeth but which has characteristics of a baleen, a filtering structure in the upper jaw made of keratin used to strain plankton from water. The sub-order Odonticeti or Toothed Whales are easily identified from the first order because of teeth structures. The blue whales are among the largest of the baleen whales. They were difficult to measure considering their size and during capture in the past with whale hunters, they were usually cut in parts to be conveniently transported that actual measurement had become an approximation. The nearest approximation of a captured specimen was at 32.9 meters (108 feet) in length and 172 metric tons (190 short tons) or more in weight. They are the largest animal to have ever existed even bigger that most dinosaur fossils unearthed. Below are some of the most common baleen whale species for your consideration, however grand in size, they feed upon the smallest planktons and schools of fish and continued to be threatened by the most lethal of all creatures in the animal kingdom barely 1/15 of its largest size (by length), humans. (by weight, imagine an average 90 kg human being against an average 172,000 kgs)

Baleen , the filtering structure in baleen whales

Bowhead Whale  – or   Balaena mysticetus are also known as Greenland Right Whale or Arctic Whale. This baleen whale belongs to the right whale family Balaenidae, characterized by a stocky dark-colored body without the dorsal fin. It is estimated to grow up to 20 meters (66 feet) in length and attains weight up to 136 tons. This type of whales confines its life only in Arctic waters and do not migrate for feeding or reproduction. They were touted to have the largest mouth in the world.

North Pacific Right Whale – Eubalaena japonica is another baleen whale characterized by large robust body structure, which is common sight in the Northern Pacific until 1840 when whaling has radically reduced their numbers. This species frequent the southeastern Bering Sea, North Atlantic, Kuril and Sakhalin islands in Russia. Lately this species had been placed among the most endangered species in the planet. Adult sizes ranges from 18.3 meters (60 feet) in length.

North Atlantic Right Whale-  Eubalaena glacialis is a baleen whale, one of three right whale species under the genus Eubalaena. An approximated 400 whales of this type thrives in the North Atlantic Ocean. This whale migrates within the waters of Gulf of Maine to Georgia and Florida for feeding grounds and giving birth to their young. Adult whales of this type ranges at  11-17 meters (35-55 feet) with the largest at 18 meters (60 feet) long with weights reaching 117 tons (106,500 kg). Calves are within 4 – 4.6 meters (13-15 feet) long at birth. They have an average life span of fifty years.

Southern Right Whale -  Eubalaena australis is the last of the three species known as Right Whales under the genus Eubalaena. These whales thrive within the Southern Hemisphere and were averaged at 12,000 spread along this area. Characterized by growth of “Whale Lice” parasitic cyamid crustaceans attached by their skin, they are easily identified among other whale species. They are seen in summer at far Southern Ocean close to Antarctica and in the winter migrates to Argentina,Australia, Brazil, Chile, Namibia, Peru, Uruguay, New Zealand and South Africa to breed.  Adult females could reach size up to 18.5 meters (61 feet) in length.

Sei Whale  -  Balaenoptera borealis is a baleen whale found extending from Southern Europe to Northwestern Africa to Norway in the Eastern North Atlantic and from Southern US to Greenland in the western. Although difficulty of distinction to their close relatives, the Bryde’s Whales and Fin Whales owing to similarity, they were known to avoid polar and tropical waters and semi-enclosed bodies of water. This type of whale is the third largest rorqual  (term referring to largest family of baleen whales, Balaenopteridae) after the Blue Whale and the Fin Whale. Adults could reach lengths of 20 meters (66 feet) and weights up to 50 tons. They are also among the fastest in the order reaching speeds of 27 knots ( 50 km/hr).

Fin Whale  – Balaenoptera physalus  is also called Finback Whale,Razorback or Common Rorqual. It is the second largest whale and the second largest animal after the Blue Whale reaching lengths of up to 27 meters (88 feet). It is mostly found in most major oceans with two distinct subspecies, the Northern Fin Whale of the North Atlantic and the larger Antarctic Fin Whale of the Southern Ocean. This species is endangered owing to subject of heavy hunting. It thrives on schools of fish, squids, crustaceans and krill.  

Blue Whale -  Balaenoptera musculus is the largest of the whale species and the largest animal to have lived. Characterized by a long and slender body structure, its size had been often hard to measure where hunted and caught specimens were often cut to manageable pieces before they could even be weighed or measured as a whole. The loss of body fluids during the decapitation have rendered inaccurate measurements but sizes of 32.9 meters (108 feet) in length and 172 metric tons (190 short tons) weight is the average. Three subspecies were identified B.m. musculus of the North Atlantic and North Pacific, B.m. intermedia of the Southern Ocean and the B.m. brevicauda (Pygmy Blue Whale) of the Indian Ocean and South Pacific Ocean.

Bryde’s Whale -  is the least known and considered unusual among the rorquals. It was named after Johan Bryde, a Norwegian consul to Africa who helped established the first whaling station in Durban, South Africa in 1908. This whale is considered small among other rorquals reaching only weights of 25 tons and lengths of 15 meters. It prefers coastal areas feeding on schools of fish like anchovy, herring and sardines.

Humpback Whale  – Megaptera novaeangliae is another baleen whale. Considered one of the larger rorquals, Humpbacks range from 12-16 meters (40-50 feet) in length and reaches an approximated 36,000 kgs (79,000 lbs) in weight. It has a distinctive body shape with unusually long pectoral fins. It is an acrobatic animal and could be easily identified throwing 2/3 or more of its body out of the water and splashing down on its back performing a “back flip”. Humpback males are also known to be musical animals producing that typical whale squeal lasting from 10-20 minutes which is suspected to have a role in mating. Estimated at 80,000 scattered worldwide, they feed on krill and fish and live an average 50-60 years.  

Minke Whale – is also called Lesser Rorqual and belongs to the sub order baleen whales under which two distinct species are identified, the Northern Minke Whale (Balaenoptera acutorostrata)and the Antarctic Minke Whale (Balaenoptera bonaerensis). The Minke is the second smaller of the baleen whales after the Pygmy Right Whale. Sizes range from 9.1-10.7 meters (28′ 10″ -35′ 1″) in length and an average of 5-14 tons weight for both male and female matured Minke Whales. Life span is at 30-50 years.

Gray Whale  -  Eschrichtius robustus is a baleen whale which has been known to travel  between feeding and breeding grounds yearly. It is the sole species under the genus Eschrichtius.  It reaches size of up to 16 meters (52 feet) in length and weighs an average of 36 tons with a life span of 50-60 years. Due to their fighting behavior when hunted, they earned the name Devil Fish. The Gray Whale thrives within the eastern north Pacific (US) and western north Pacific (Asia) with the population scattered in the area.

Note: Research Sourced from wikipedia