A fact that shows just how essential the ability to hear is to all living things on the earth is that while scientists have identified various kinds of amphibians, reptiles, fishes, and mammals who are sightless, they have been unable to find any naturally deaf species. That said, the ability to hear does not specifically require ears. Only vertebrates have ears, while invertebrates utilize various other sense organs to recognize the vibrations we know as audio waves.
Insects, for example, have tympanal organs that work as well as ears, and in fact give them far better hearing than humans; as an example, a species of fly that is a parasite to crickets can locate its prey at some distance just by hearing its song. Spiders and cockroaches have tiny hairs on their legs that they use to pick up sounds, and caterpillars have similar sound-receiving hairs on their bodies. Elephants not only have large ears, they can also hear using their feet. They are particularly attuned to low-frequency sounds, and can detect the sound of thunderstorms or the deep-voiced call of other elephants many kilometers away.
Fish are interesting too. Fish don’t have ears, but are able to perceive sounds underwater using lateral lines that run horizontally along the length of their bodies. Dolphins have external eardrums on the outsides of their bodies that are so sensitive that they have the best sense of hearing among animals, and are able to hear 14 times better than humans.
Not only do many animals have better quality hearing than humans, they can hear more sounds, detecting frequency ranges that are much higher and lower than the range that humans are capable of hearing. Among domesticated animals, cats have the sharpest hearing, and can hear frequencies between 45 Hz and 64,000 Hz (humans can hear frequencies between 64 Hz and 23,000 Hz). Birds, especially owls, have excellent hearing. Owls are particularly skilled at detecting the precise location of a sound – and detecting it very quickly. They can pin-point the origin of a mouse scurrying in under 0.01 seconds. Bats and dolphins actually extend their hearing abilities usingecholocation, a form of sonar in which they emit tiny clicks or chirps and then “see” the objects they bounce off of when the sounds return to them. This echolocation is so precise that with a single chirp, a dolphin or bat can tell the exact location, direction, size, and even the physical nature of objects in its environment. Scientists have proven that by using echolocation dolphins can detect objects the size of a small coin from over 70 meters away. And if you want a real display of hearing, bats can not only hear insects flying 30 feet away from them, they can then pursue and catch them in mid-air, all in total darkness.
Looking at the animal world is a great reminder of how vitally important hearing is.