When it comes to the loudest inhabitants of the world ocean, many immediately think of the blue whale, which is capable of making sounds heard hundreds of kilometers away. However, contrary to expectations, the loudest natural noise in the marine environment is not made by whales, but by tiny shrimp known as snapping shrimp (pistol shrimp or alpheid shrimp).
Blue whale vs. snapping shrimp: an unexpected rivalry
Blue whales are certainly impressive in their scale and capabilities. Their thunderous songs reach 188 decibels and serve for communication over vast distances. However, the collective noise produced by trillions of snapping shrimp surpasses even these levels, reaching an astonishing 246 decibels underwater. This is equivalent to 160 decibels in the air, which far exceeds the noise level of a jet taking off (about 140 decibels) and the human pain threshold.
The "shrimp layer" phenomenon and its impact on technology
The so-called "shrimp layer" represents dense clusters of snapping shrimp creating a constant sound background in the ocean. This noise is so intense that it can "blind" submarine sonars, making them useless in areas inhabited by these shrimp. Hydroacousticians located under this layer cannot distinguish sounds coming from above, and vice versa. The only way to overcome this sound "blockade" is to physically raise the mast through the shrimp layer to receive signals directly.
Sound mechanics: how snapping shrimp create their noise
The source of this incredible noise lies in the unique anatomy of snapping shrimp, representatives of the genera Alpheus and Synalpheus. These small shrimp, measuring only 3–6 centimeters long, have asymmetrical claws, one of which is significantly larger than the other and can be either right or left. The large claw is equipped with a special mechanism: a small protrusion on one side enters a recess on the other, creating a powerful hydrodynamic effect when snapping shut.
Cavitation: a physical marvel in miniature
When the claw snaps shut at lightning speed, water is expelled at an incredible speed, reaching 100 kilometers per hour. This leads to the formation of vapor bubbles in a process known as cavitation. The bubbles rapidly expand and then collapse, causing a sharp sound shock, a flash of light, and even a brief temperature rise of up to 7700 °C. For comparison, the surface temperature of the Sun is about 5500 °C. This phenomenon, called sonoluminescence, represents the conversion of sound energy into light and is still a subject of scientific research.
Hunting with sound: the snapping shrimp's strategy
Snapping shrimp use their powerful clicks not only for communication but also for hunting. Hiding in their burrows or under rocks, they stalk their prey using their sensitive antennae. Once the potential victim is within reach, the shrimp quickly pounces, pulls back its large claw, and makes a "shot". The powerful shockwave stuns or even kills small fish or other crustaceans, after which the shrimp drags the prey into its hideout.
Communication and social behavior
In addition to hunting, the clicks of snapping shrimp are used for communication within the species. They help establish social connections, define territory, and find mates. In some cases, shrimp form complex colonies with role distribution, which indicates a high level of social organization.
Impact on human activity
The intense noise created by snapping shrimp has significant consequences for marine navigation and military technology. It can interfere with sonar systems used to detect submarines and other objects. In areas of mass shrimp habitation, sonar becomes practically useless, which can be used in anti-submarine warfare tactics.
Moreover, cavitation effects caused by mass clicking can create micro-damage on the surface of ship propellers and other underwater structures. Although this damage is usually minor, over time it can lead to reduced equipment efficiency and require additional maintenance.
Distribution and ecological role
Snapping shrimp are widespread in the warm waters of tropical and subtropical regions around the world. They inhabit shallow waters, coral reefs, mangroves, and sandy bottoms. These shrimp play an important role in the ecosystem, participating in food chains and contributing to soil aeration through their burrowing activities.
Symbiosis with other species
Some species of snapping shrimp engage in mutually beneficial relationships with goby fish. The shrimp provide the fish with shelter in their burrow, while the gobies, with better vision, warn the shrimp of danger. This symbiosis is a striking example of coevolution and complex interactions between different species.
Interesting facts and scientific research
- Sound uniqueness: Each species of snapping shrimp produces clicks with unique acoustic characteristics, which allows scientists to use them to study biodiversity and monitor marine ecosystems.
- Medical potential: Research into the cavitation effects created by snapping shrimp may have applications in medical technologies, such as ultrasound therapy and targeted drug delivery.
- Robotics: The shrimp’s snapping mechanism has inspired engineers to develop micromechanical devices and new types of underwater robotic systems.
Snapping shrimp, these tiny but incredibly powerful inhabitants of the ocean, demonstrate just how amazing and diverse the underwater world is. Their ability to create noise that surpasses the loudest sounds made by large marine animals is not only an interesting biological phenomenon but also has practical implications for humans. Studying these shrimp continues to reveal new aspects of physics, biology, and ecology, reminding us that even the smallest creatures can have a huge impact.
For those who want to see this amazing process with their own eyes, we recommend watching the video below, where you can observe the moment of bubble collapse and its accompanying effects in detail.