Whales, dolphins and porpoises are large mammals called cetaceans that live mostly in the seas and oceans. Dolphins and porpoises are small whales.
Like all mammals, whales have lungs – this means they have to come to the surface to breathe every 10 minutes or so, although they can stay down for up to 40 minutes. A sperm whale can hold its breath for 2 hours.
Whales breathe through blowholes on top of their head. When a whale breathes out, it spouts out water vapor and mucus. When it breathes in, it sucks in about 2,000 liters of air within about 2 seconds.
Like land mammals, whales nurse their babies with their own milk. Whale milk is so rich that babies grow incredibly fast. Blue whale babies are over 7 m long when they are born and gain an extra 100 kg or so a day for about 7 months.
Killer whales or orcas are big deep-sea predators, growing to as long as 9 m and weighing up to 10 tons. They feed on fish, seals, penguins and dolphins.
Humpback whales live together in groups called pods and keep in touch with their own `dialect’ of noises.
Toothed whales, such as the sperm whale and the orca or killer whale, have teeth and prey on large fish and seals. The six groups of toothed whale are sperm whales, beaked whales, belugas and narwhals, dolphins, porpoises, and river dolphins.
Baleen whales, such as the humpback and blue, have a comb of thin plates called baleen in place of teeth. They feed by straining small, shrimp-like creatures called krill through their baleen. There are five baleen whale groups, including right whales, grey whales and rorquals. Rorquals have grooves on their throats and include humpback, minke and blue whales.
The blue whale is the largest creature that ever lived. Blue whales grow to be over 30 m long and weigh more than 150 tons. In summer, they eat over 4 tons of krill every day – that is 4 million krill.
Whales keep in touch with sounds called phonations. Large baleen whales make sounds which are too low for humans to hear, but they can be heard by other whales at least 80 km away.
Most baleen whales live alone or in small groups, but toothed whales – especially dolphins – often swim in groups called pods Male humpbacks make elaborate ‘songs’ lasting or schools.