An interesting observation that indicates just how essential hearing is to all living things on the earth is that while researchers have identified various kinds of reptiles, amphibians, mammals, and fishes who are blind, they’ve been unable to find any naturally deaf species. However, hearing doesn’t specifically call for ears. Only vertebrates have ears, whereas invertebrates use various other sense organs in order to recognize the vibrations we all know as sound 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. Hair can also be used to detect sounds. In spiders, cockroaches and caterpillars, tiny hair cells play the role of ears. The spiders and cockroaches have the hairs on their legs, while the caterpillar has them along its body. 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.

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. Cats have the most acute hearing among animals we have domesticated as pets; while humans can only hear sounds between 64 and 23,000 Hz, cats can hear sounds between 45 and 64,000 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. Dolphins can use echolocation to detect objects the size of a small coin over 70 meters away. A bat can detect an insect 30 feet away in complete darkness.

A quick look around the animal world is a great way to remind ourselves how vital hearing is.