When thinking of noisy marine wildlife, your mind likely jumps to something big like a whale – and rightly so, with the sperm whale clocking in an impressive 230 decibels for their communicative clicks, which are amplified by the oil-filled spermaceti organs that give them their name. Following close behind however is a tiny crustacean whose massive claw packs an audible punch.
Snapping shrimp, also known as pistol shrimp, can create a sound louder than a gunshot, clocking at 210 decibels. Collectively they create the loudest sound in the ocean, and a recent study presented at the Ocean Sciences Meeting 2020 has discovered they’re only getting louder, spelling big problems for marine ecosystems.
As part of the family Alpheidae, they’re famed for their asymmetrical claws, one of which is huge, and there are about 119 species including The Wall-inspired Synalpheus pinkfloydi. They roam the oceans in colonies of over 300 members snapping their enormous claws as they go (sort of like the gangs in West Side Story only with fewer pirouettes) and are a nightmare for submarines.
The chorus of snapping shrimp calls to bacon lovers everywhere.
The noise they make collectively is known as the “shrimp layer” and it’s so loud it can block out a submarine’s sonar. This sound is created as a result of the speed at which they snap their claw – approximately 100 kilometers (62 miles) per hour. This high-speed click creates a vacuum that expels a searing bubble of heat that at 4,400°C (7,950°F) is almost as hot as the surface of the Sun. This high-pressure cavitation bubble collapses producing sonoluminescence, the combination of light and sound. They’re the Snap, Crackle and Pop of crustaceans.
According to new research, these rambunctious gangs of crustaceans are getting even louder and increasing ocean temperatures are to blame. The discovery was made when marine biologists Aran Mooney and Ashlee Lillis at Woods Hole Oceanographic Institution tested the effects of changing temperature on the shrimp tanks in their lab.
Listening in to the shrimp, they found that as the temperature increased so too did the frequency and volume of the snaps. As cold-blooded animals, the body temperature and activity of snapping shrimp is largely controlled by their environment, so warmer waters increase their activity. The same is seen in ants on land that move slower when it’s cold and faster when it’s hot.
"We can actually show in the field that not only does snap rate increase, but the sound levels increase as well," Mooney said. "So, the seas are actually getting louder as water [reaches] warmer temperatures."
Louder snapping shrimp potentially poses a danger to marine ecosystems where many animals use sound to communicate. If the oceans get louder, there’s a chance it could impact marine animals’ chances of finding a mate, defending their territory, and hunting for food. The existing research can’t support or deny if this is likely to happen, but Mooney notes that it’s an important avenue for future investigation.
And it’s not just fish that might suffer. Snapping shrimp are already known to interfere with sonar instruments, which are vital to fisherman searching for catch. On top of which their racket could potentially block instruments used by the Navy to detect mines, posing a threat to national defense.
The more we discover about our oceans the stranger it seems that it has a reputation for peace and tranquility. Find out about more obstreperous ocean life with singing whales, loud-mouthed fish and even a worm whose racket goes beyond the human threshold for pain.