The ability to hear is important to just about all living creatures; even though scientists have discovered many species of blind fishes, amphibians, reptiles, and mammals, no deaf vertebrate species have been identified. That said, hearing doesn’t necessarily call for ears. Only vertebrate animals have ears, whereas invertebrate animals utilize various other sense organs in order to recognize the vibrations we know as audio 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. 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. 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.
Sound travels both faster and farther through water than it does through the air, and even though fish don’t have ears, they can effectively detect sounds using lateral lines that run horizontally on the sides of their bodies. 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. Many animals not only hear better than we do, they hear more sounds, easily detecting sounds in frequency ranges far below or above the frequencies that we humans can hear. 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). Owls also have phenomenal hearing, both in terms of acuity and reaction time; they can detect the exact location of a scurrying mouse in less than 0.01 seconds.
Some species, such as bats and dolphins, extend their hearing abilities by using a form of sonar called echolocation, in which they emit ultrasonic chirps or clicks, and then interpret the sound waves as they return from objects the waves strike. Echolocation is extremely precise. It only takes one chirp to determine an objects’ size and location. Dolphins can use echolocation to detect objects the size of a small coin 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.
