Weighing only 50 grams, this creature can produce sounds louder than the roar of a jet engine.
This tiny creature is the Alpheus bellulus, commonly referred to as the pistol shrimp. This species inhabits the waters of the Indian Ocean and the western Pacific Ocean.
The pistol shrimp Alpheus bellulus, known for being one of the loudest creatures in the ocean, may be small in size, but it can generate an incredibly loud sound that stuns its prey.
Pistol shrimp Alpheus bellulus. (Photo: Aquaorinoco)
In fact, the sperm whale is known to produce the loudest sound, reaching up to 230 decibels (dB). However, in terms of size-to-sound ratio, the loudest creature on the planet is likely the pistol shrimp Alpheus bellulus.
According to experts, this shrimp only measures about 4 to 5 cm in length and weighs 50 grams, yet it can emit sounds up to 200 dB. This sound is louder than a jet engine or a gunshot. Fortunately, this crustacean lives underwater, as the human ear can only tolerate sounds up to 120 to 130 dB.
What gives this small shrimp its extraordinary ability?
The Secret Weapon of the Pistol Shrimp
Researchers reveal that the secret of the pistol shrimp lies in its oversized claw, which is longer than half its body length.
The Alpheus bellulus possesses asymmetric claws. The larger claw, dominating the other, becomes the “weapon” that enables this creature to produce extremely loud sounds to hunt its prey. Specifically, by snapping its claw at an incredibly fast speed, the larger claw creates a bubble of air that rushes forward at about 100 km/h, accompanied by a loud bang.
Experts indicate that the shockwave generated by this creature can stun small shrimp and fish within a 2-meter radius.
The asymmetric claws are the secret weapon of the Alpheus bellulus. (Photo: Newscientist)
When gathered in large groups, pistol shrimp can create sound wave disturbances that interfere with underwater communication devices.
Experts explain that when two pistol shrimp confront each other, they will suddenly snap their larger claw toward their opponent, creating a powerful jet of water at speeds of up to 30 m/s.
While the force from this strike rarely results in death, it can cause the defeated shrimp to lose its claw or suffer serious injuries. This is a result of the shockwave generated from the snapping motion of the pistol shrimp.
Scientist Phoevos Koukouvinis at the University of London and his colleagues simulated what happens after the pistol shrimp snaps its claw at various speeds. The results showed that after the claw snaps shut, the friction in the water jet causes it to burst forth quickly, creating a vortex in the surrounding water.
When this vortex spins fast enough, it creates a void in the center. Eventually, when the void collapses, it releases a powerful shockwave. Experts were amazed that this process occurs in less than half a millisecond.
The force from this strike can cause the defeated shrimp to lose its claw or suffer serious injuries.
Being only about 5 cm long, the “weapon” of the pistol shrimp is aimed at similarly sized prey. However, researcher Nancy Knowlton at the Smithsonian Institution in Washington warns against putting hands into a tank with pistol shrimp.
Researcher Nancy Knowlton states: “You won’t feel anything if you just dive near a coral reef. But if you put your hand in front of a pistol shrimp’s claw, you will feel a lot of pain from the shockwave attack.”
In 2020, scientists at the Woods Hole Oceanographic Institution conducted experiments on the noise produced by pistol shrimp in the ocean at different water temperatures.
The results concluded that as ocean temperatures rise due to climate change, pistol shrimp will produce sounds more frequently and loudly than before. This is also their response to environmental changes, making the ocean more “noisy.”
