Whales, dolphins and porpoises spend their whole lives in the water, but how do you think their diving ability compares to us humans? Without scuba gear, trained humans can dive for as long as five minutes and down to about 30m (100ft) deep. Some cetaceans only dive for a similar amount of time, but with their streamlined bodies, which are made for swimming, mean that they can cover distances up to 210m (690ft) in the same time—they are around seven times faster than humans!
As they hunt and travel underwater, most whales, dolphins and porpoises can hold their breath longer than five minutes. The sperm whale can dive for over two hours and descend three kilometres deep! Humans can only travel that deeply in a diving vessel with air supply and thick steel walls. Scientists still don’t know how the sperm whale can dive so deeply and for so long.
Even though they are able to hold their breath for longer than us, cetaceans eventually have to come up to the surface to breathe air. As long as they are awake, that is no problem at all, but what do they do when they need to sleep? Imagine having to wake up every 5 to 10 minutes because you have to breathe! That wouldn’t be fun, would it? Indeed, whales, dolphins and porpoises do not wake up every few minutes to swim to the surface. Instead, they have adapted their sleeping pattern to their underwater life in a very interesting way. Their brain, just like ours, is split up into two halves. When we sleep, both halves of our brains are not conscious and we can’t actively control our body anymore. To avoid this, whales and dolphins never sleep with both halves of their brain—just one half rests at a time! This gives them the ability to continue swimming, surfacing to breathe and to keep one eye out for predators.
Whales, dolphins and porpoises produce sounds like squeaks, grunts, barks and groans for normal communication. Toothed whales have developed a special sense which they use for hunting: echolocation. Baleen whales are not able to echolocate, but they produce very deep, slow sounds. Male humpback whales are especially famous for the long, beautiful songs they sing. Scientists are not sure why they sing, although it is thought that they might use song to attract females. What we do know is that the whales in the Atlantic Ocean sing different songs to those in the Pacific Ocean. As sound travels extremely quickly in water, those songs can be heard over very long distances.
Would you like to hear a whale song?