A fact that indicates how important the ability to hear is to living species on earth is that while researchers have identified various kinds of amphibians, reptiles, mammals, and fishes who are sightless, they have been unable to find any naturally deaf species. However, hearing does not necessarily call for ears. Only vertebrates have ears, while invertebrates use other types of sense organs in order to perceive the vibrations we know as sound waves.
In the case of insects, they have extremely sensitive tympanal organs which offer excellent hearing capabilities. Certain fly species can locate their prey exclusively via its song from a substantial distance. In some species, tiny hairs take the place of ears; in spiders and cockroaches these hairs are on the legs, while in caterpillars they are along the surface of its body. One species known for its acute hearing is the elephant. Elephants have large ears, but they can also hear through their feet. This form of hearing is so acute that elephants can detect the sound of thunderstorms or the low-frequency call of other elephants coming from many kilometers away.
Even though fish don’t have ears (they perceive sounds using lateral lines that run horizontally along their bodies), they can detect sounds that humans would not be able to hear. The dolphin is believed to have the best hearing among animals. Dolphins have no ears. Instead they have external ear drums on the outside of their body. 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 using echolocation, 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. Using echolocation, bats and dolphins can determine a great deal about objects they can’t even see, including the objects’ size, location, and even their physical nature. 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.