These noisy creatures like to make themselves heard, whether it’s a deafening defence system, a blaring contact call or an ear-splitting mating song
Water boatman – The aquatic insect that’s as loud as a revving car
Rather than sing sweet soliloquies with its mouth, the male water boatman serenades females with its musical genitals. It rubs them on its abdomen to create sounds, in the same way as a cricket emits its characteristic chirps by rubbing its legs. Amazingly, the lesser water boatman is able to pump out these tunes despite being only two millimetres (0.1 inches) long. Even though 99 per cent of the sound is lost when it transfers from water to air, the songs are still audible – someone walking nearby would be able to hear them singing from the riverbed. Pound for pound, the lesser boatman is the loudest animal on the planet.
A lion’s thundering roar brings home wandering cats
A lion’s roar can match the volume of a clap of thunder, and their sonic secrets lie in their vocal cords, or folds. Most animals, including humans, have triangular vocal folds that protrude into the throat, but lions and tigers have flat, square-shaped folds that respond more efficiently to passing air. The lion’s vocal cords are also extremely resilient and elastic. This lets the big cat roar loudly using low lung pressure. Interestingly, a lion’s roar and a human baby’s cry are strikingly similar in the way they are produced. Infants have gel-like vocal folds that produce rough, raspy sounds that rouse mothers in the night and set airplane passengers’ teeth on edge.
Cicada – As noisy as being on the front row at a rock show
Cicadas aren’t just the loudest insects on Earth; they also show promising musical talent. Each species has a distinctive song so that females know which one to tune into to find a suitable mate. Cornered cicadas can also use blasts of sound to repel predatory birds. Males in the same family, or brood, will even team up to make it difficult for birds to get close. Their song is actually painful for a bird to listen to, and prevents them from communicating and hunting in groups. Two ridged membranes known as ‘tymbals’ sit at the base of the belly, and are controlled by muscles in the insect’s abdomen. When the muscles contract, the membranes are drawn towards each other, and their unique sound is pumped out.
Lesser bulldog bat – Humans can’t hear the loudest winged animals
These bats emit as much sound as a police siren, and can focus it into exact beams in any direction they choose. They use echolocation to hunt, meaning they emit sounds and listen out for the resultant echo to map out their surroundings. Any unfortunate invertebrate that breaks these beams of sound is in imminent danger of becoming a bat’s breakfast. All of this noise is ultrasonic, as only high-pitched sounds can detect the minute movement of insect wings. The problem is that at such high frequencies, the sound can’t travel far. The maximum distance a lesser bulldog bat’s sonar can reach is around 12 metres (40 feet). These calls have to be slowed down ten times in order for us to hear them, and the blast is above our pain threshold. The bats squeeze their ears shut to prevent hearing damage, even from their own squeals.
Howler monkey- The primate that booms like a marching band
With deafening calls that can be heard over a distance of five kilometres (three miles), howler monkeys are the loudest animals on dry land. They produce roughly the same amount of sound as a 200-member marching band, using a bone beneath the tongue called the hyoid. It’s a hollow, bowl-shaped resonating chamber that hugely amplifies the sounds that leave the howler monkey’s mouth. The ear-splitting, guttural sounds attract female howlers at the same time as repelling competing males. The day usually starts with a territorial call, which nearby males answer with their own. This tells a male how close his competitors are and warns neighbours to keep away from his patch. Bizarrely, there is a relationship between the volume of a howler monkey’s call and the size of its testes. Those with smaller reproductive organs produce the loudest sounds and have the largest hyoid bones. It’s thought that the energy it takes to form the hyoid leaves other areas of the body with less room to grow.
Blue whale – Calls that cross continents
Ocean giants use physics to keep in contact with other whales, making the most of how fast sound travels in water. As the particles of the sea are closer together than those in air, sound travels almost five times faster through liquid than air. Blue whales are usually solitary, and even those that live in pairs can swim several kilometres apart. This has led to the development of amazing long-distance communication using low-frequency sounds. Some are so low in pitch that they are below the threshold of human hearing, but are as loud as one ton (2,000 pounds) of TNT exploding at a distance of 30 metres (100 feet).
Pistol shrimp – Sound so loud it can boil water
Rather than communicating with sound, the pistol shrimp uses it as a weapon to stun its prey. It’s hard to believe this tiny creature could drown out a rocket during take-off, but even more amazing is how it does it. Pistol shrimp are asymmetrical. One claw is a tiny pincer while the other is an enormous clamp that can grow to half the size of the its entire body. The large claw itself isn’t symmetrical either; one side has a socket while the other half has a plunger. When the claw snaps shut, the plunger is slammed into the socket and forces out a jet of water at 115 kilometres (72 miles) per hour. Tiny bubbles swell suddenly due to the low pressure this generates, then collapse again when the pressure returns to normal. This creates a loud snapping sound, and briefly generates temperatures of 4,430 degrees Celsius (8,000 degrees Fahrenheit), which is almost as hot as the surface of the Sun.
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