We all learn from an early age the noises that different animals make. Cows go moo, pigs go oink, and so on. But have you ever stopped to consider why animals make sound? What purpose does it serve, and why are there so many different sounds?
Animals make sounds to communicate to others, including warnings, threats, to show dominance, and to attract a mate. Animals make two types of sound; vocal and mechanical. Vertebrates can make vocal and mechanical sounds. Invertebrates make mechanical sounds and cannot produce vocal sounds. An example of a mechanical sound would be a cricket rubbing its legs together.
Animals on land sound very different from aquatic animals, and larger animals tend to have deeper sounds. In this article, we look at how animals use different sounds on land and in the oceans.
Different Types of Sound
Each order of animals produces sound in a different way. There are two types of sound production; vocal sound and mechanical sound. Vocal sound production is performed by vertebrate animals and is produced via the respiratory system.
Invertebrates use mechanical sound, but they cannot produce vocal sounds. Mechanical sound is produced by rubbing body parts together or by making contact with an object. Many vertebrate species also create mechanical sounds.
Most mammals have vocal cords, just like humans, or a variation of vocal cords. Sound is produced when air passes through, creating vibrations. Toothed whales have phonic lips similar to a human’s sinus (air cavity surrounded by dense bone). Baleen whales replicate sound almost identically to humans, as they possess vocal folds much like we have vocal cords.
There are many different types of vocal sounds:
Many animals can create multiple types of sounds. For example, dogs can bark, growl, howl, chuff, and cry. Each sound represents a different intent. Barks can be used to warn of a perceived threat or to get attention. Howling, also used by wolves, is a form of communication used to bond a group of dogs.
Many dog owners will witness their dog howling along with emergency service vehicle sirens. To a dog, the sirens sound similar to a dog howling.
Woodpeckers do not create birdsong like other birds, but they use their strong beaks to create sound by tapping the bark of trees to create thuds like a drummer uses a stick to beat a drum.
Marine mammals use a variety of clicks and whistles to communicate. Sound travels much further in water than it does in air. A whale call can be heard more than 4000 miles away.
Rabbits and hares use vocal grunts when they feel stressed or frustrated, but they also use mechanical sounds to communicate. When they sense danger, they will stamp on the ground with their hind feet to warn other group members.
Invertebrates are not capable of creating vocal sound, so they rely on other forms of sound production. Insects like grasshoppers and crickets create sound by rubbing their legs together. Cicadas have a membrane on their abdomen that works like a dog training clicker. The membrane is contracted, which creates a clicking sound. The membrane then relaxes to produce a second, quieter click. They also have a resonating chamber that works like a speaker to amplify the sound.
Frogs create loud croaks by forcing air past their larynx. The sound is intensified thanks to an air sac under the chin, which acts like a speaker. Males are most vocal during the breeding season, as they use their calls to attracts females.
How Is Communication Beneficial?
Aquatic animals can use their tails to create mechanical sound, warning others of danger or as a display to intimidate potential predators. Whales use their large tails to slap the water surface. This creates a loud sound and a large water spray. Both are also used to startle a would-be predator.
American beavers use a similar technique to warn other beavers of potential danger. Their tails are shaped like a paddle. The wider and thicker the tail, the greater the sound.
The vocal sound is also used as a threat. Walruses can create loud booms or clangs to scare off predators, warn others of danger, and also show dominance over smaller walruses.
During courtship, many animals use sound. All bird species have their own song, a combination or pattern of chirps designed to attract a mate. Aquatic mammals also produce different sounds during the breeding season.
Female animals will often reserve a distinctive sound for their offspring. A mother can often tell her young apart from another female’s by the sounds they make. If a youngster moves too far from their mother and gets lost, the mother will produce a call or sound designed to attract the baby back to her. The infant will also produce a similar sound, much like human babies cry when they are hungry or uncomfortable.
Sound is a key form of showing dominance. A dominant dog will often growl of chuff to another dog who is challenging them. Often, this type of communication is enough to stop a physical fight and avoids the risk of injury.
Hunting is often reliant on sound. Scientists believe that sperm whales can use sound to stun their prey. This is also known as the ‘big bang hypothesis.’ A sperm whale is responsible for the loudest sound from an animal ever recorded. The click was recorded off the coast of Norway and measured 234 dB. This data is a key piece of evidence in the support the ‘big bang’ hypothesis.
Crab shrimp can create a sound wave by snapping their jaws together, creating an air bubble. The bubble creates a sound wave when it bursts, stunning nearby fish and making them easier to catch.
Many people believe that fish do not make any sounds. However, they are capable of producing a variety of sounds, especially for courtship. Some fish use their swim bladder to create sound. They use a muscle, called a sonic muscle, to contract and expand the swim bladder to create drumming sounds. Some fish create sounds more like a purr or a pulse.
Animals That Make No Sound
While most animal species can make sound, either vocally or mechanically, some species make no sound.
Animals that move will always make sound with their bodies, but this is unconscious sound production. Mechanical sounds are often made deliberately by the animal.
Species such as snails, slugs, and worms do not purposely create sound as a form of communication. The only sound they are known to produce is during movement when their bodies rub against the ground.
Aside from the snapping sounds they make during feeding, sharks are also considered silent animals. They do not growl or click, and they use body language to communicate rather than sound.
Jellyfish are another aquatic animal that does not produce sound deliberately. They can create sounds waves using their tentacles or bell as they swim, but this is unconscious sound production. Jellyfish cannot produce sound for communication as they do not have a brain capable of creating the required complex patterns of behavior to form sound.
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