There are two types of whale; baleen and toothed. The key difference between them is the way they feed and what they have inside their mouth.
Baleen whales have baleen plates, or sheets, which sieve prey from seawater. Toothed whales have teeth and they actively hunt fish, squid and other sea creatures. Dolphins and porpoises all have teeth and rather confusingly are known as ‘toothed whales’ too!
Another obvious difference between baleen and toothed whales is the number of blowholes on top of their head; baleen whales have two whereas toothed whales have one. There are only 15 baleen whale species and they are generally larger than the 77 species of toothed whales – except for the mighty sperm whale, the largest toothed whale.
Baleen whales are generally huge; the largest is the biggest creature to have ever lived on Earth - the blue whale. Baleen whales are aptly nick-named the ‘great whales’ yet they survive on the teeniest (and most abundant) animals in the ocean; they are filter feeding specialists and target shoals of small fish or clouds of zooplankton and krill in the sea. Their baleen plates or ‘whale bones’ are made from a material similar to human fingernails and animal horns; they are strong, flexible and feathered at the edges, rather like bristles on a brush. Huge volumes of seawater are strained through the baleen plates which sieve and retain little sea creatures in huge quantities.
Right whales and bowheads are skimmers or grazers and gather food by swimming slowly, open-mouthed through dense patches of it. Humpbacks, blue whales and fin whales are gulpers; their throats are expandable and enable them to take enormous mouthfuls of seawater and sieve out their prey; gray whales are bottom feeders and sift prey from mouthfuls of mud on the seabed.
Most baleen whales are migratory and tend to follow the same basic migratory pattern. Some, such as humpbacks and gray whales make very long, seasonal migrations. Our understanding of why they do this is that they face a dilemma; there is much more whale food available in cold polar oceans but these environments are risky and challenging for vulnerable newborn whales who thrive in warmer seas. The baleen whale solution to this is to feed in cold water feeding areas for as long as possible in the summer months and then swim to warm, calm water nursery areas. Not all baleen whales migrate; Bryde's whale, the bowhead whale and sei whale are all non-migratory.
Baleen whales do not echolocate but they do make sounds to communicate with one another, display and attract mates, repel rivals and establish territories. Different baleen whales use a variety of sounds including singing, moans and short pulses.
Baleen whale group sizes are generally small; they often appear to be alone but are found to be in acoustic contact with others. Large groups of baleen whales are generally uncommon.
Baleen whales are grouped into four families: rorqual; right; gray; and pygmy right whale. However, the exact number of species (currently 14) and their relationships to one another are still matters of hot debate as scientists are finding what they believe to be new species within species.
Baleen whales - quick facts
- Consist of four families: rorqual; right; gray; and pygmy right whale.
- Usually found alone or in in small groups
- Do not echolocate
Did you know?
Rorqual is derived from the Norwegian word röyrkval which means "furrow whale". This is thought to refer to the long folds of skin in the lower jaw.
Right whale and bowhead whale family
The right whale and bowhead whale family is made up of three right whale species and the bowhead whale. They are enormous, rotund, stocky whales who can grow up to 20m and weigh 90 tonnes (90,000kg). They have huge heads measuring up to a third of the total length and their backs are smooth with no dorsal fin or ridge. Right whales and bowhead whales are slow swimmers; they skim feed or graze using their impressively long baleen plates to filter food from seawater. These whales were intensively hunted during the commercial whaling years and are struggling to recover; in fact both the North Atlantic right whale and the North Pacific right whale are endangered and continue to decline in numbers, the southern right whale is slowly recovering. Subsistence whaling of bowhead whales is still practised by Alaskan and Greenlandic aboriginal subsistence whalers.
Gray whale family
The gray whale family only has one member – the gray whale. Gray whales are the most coastal of all baleen whales as they live in shallow water where they feed on the seafloor. They swim on their sides, close to the seabed and suck muddy sediments into their mouth and sieve out their prey using short, course baleen plates in their mouths.
Gray whales grow up to 15.2m (50ft) long. Their skin is very mottled and this is caused by patches of whale lice and parasitic barnacles living on them. They have a bumpy dorsal ridge and no dorsal fin. Gray whales undertake the longest migrations by a mammal species.
Pygmy right whale family
The pygmy right whale family like the gray whale, has a single member! As the name suggests, this is a relatively small whale by baleen whale standards (up to 6.5m long and 3,400kg) and is the most mysterious one too. There is very little known about the pygmy right whale as they are rarely seen at sea. Pygmy right whales are found only in the southern hemisphere and their exact range is unknown.
The rorqual family is the biggest baleen family with nine members, including the blue, fin, humpback, Bryde’s, sei, and minke whales. Rorquals are sleek, slender, streamlined whales, with pointed heads and flippers. They are lunge-feeders and have deep ‘throat grooves’ extending from the mouth to their belly button. Throat grooves are long folds in the skin which expand when they feed. As the whale gulps huge quantities of seawater, the throat bulges like a giant balloon. Rorquals vary in size from the smallest minke whale 8.8m (29ft) long to the blue whale who can reach 33m (108ft) long.
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