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The Incredible Snapping Shrimp:
Uncovering the hidden secrets of the noisiest animal in the sea
What do you hear when you put your head in the ocean? Chances are you've heard the sounds produced by a specialized type of shrimp and not even known it! One of the most common and amazing sounds in most temperate to tropical seas is the crackling produced by tiny shrimp with a specialized claw. No, not the kind of shrimp people eat, but a type of crustacean called the snapping, or pistol, shrimp! Their sizzling sound, sometimes described as "frying fat", "burning twigs", or "pop rocks" is so prolific and persistent that it can even interfere with human sonar and influence the navigation of whales, fish, and microscopic plankton!
At Sound Ocean Science, we are dedicated to big thinking about ocean ecosystems and to uncovering mysteries of the sea that don't get a lot of attention. This includes novel research to increase our knowledge of tiny but supersonic creatures like the snapping shrimp, a topic we are pursuing globally. Our work measuring soundscapes is also improving habitat monitoring efforts and bettering our understanding of biodiversity.
Find out more about these amazing creatures in the sections below!
Listen to a selection of snapping shrimp symphonies we have recorded around the world
Sounds within offshore tuna shoal in Mozambique
Shallow seagrass soundscape
Shallow peat reef soundscape
What are snapping shrimp?
Snapping shrimp, also known as pistol shrimp, are a hyperdiverse group of caridean shrimp species easily recognized by their oversized "snapping claw".
A huge number of these noisy creatures live in shallow seafloor ecosystems, including reefs, rocky shores, kelp forests, and seagrass. Hundreds of different species of this type of shrimp live in colonies hidden within in coral reefs, oyster beds, kelp forests, and rocky shores, where they make quite the audible racket.
The snapping shrimp group represent an incredible diversity of species with different colour patterns, life histories, symbioses, and adaptations. New species continue to be described (over a thousand so far), and we still know little about the majority of their habits, lifestyles, or even what all that snapping is about!
How loud can a shrimp snap?
A single snap produced by a snapping shrimp may only last less than a millisecond but can reach up to 210 dB - this rivals the loudest biological sounds in the sea!
How do shrimp make such a sound?
These tiny organisms range from a few millimeters to centimeters in length, yet pack a huge punch (and sound)! So how exactly do they do it?
All snapping shrimp possess a giant claw (also known as the large major chela) which can grow up to half the size of their body. When rapidly snapped shut, the chela causes the collapse of a cavitation bubble in-between the pincers producing a loud sound.
ADD link to videos on shrimp sound production.
Snaps heard around the world
The sound produced by snapping shrimp has been identified in many areas of the globe primarily in tropical, sub-tropical and warmer temperate oceans. However, recently a study identified sound dominated by snapping shrimp as far North as Scotland. This is the coldest region snapping shrimp have ever been recorded but that’s not to say they may be found in even the poles!
History of the discovery of the snap
To the human ear, the snapping these shrimp produce is identified as a distinct crackling sound. Throughout history, this ocean noise was posited to be a combination of phenomena including shipworms, volcano activity, and rolling pebbles. However, after analysing underwater audio recordings during WWII it was later discovered that the sound was in fact produced by dense populations of snapping shrimp.
Why do they snap?
The snapping noise is considered to have multiple roles in the shrimps habitat including intra- and inter- specific communication. This communication can be used in fights to defend territory/burrow against competitors or predators and to stun or catch prey. However, it is also believed that snapping shrimp can be an important indicator of reef health. This indicator may further influence a range of animal dependent activities including navigation, habitat selection by settlement-stage larvae and perhaps even function as an auditory cue for migrating cetaceans to avoid shallow shorelines.
Snapping shrimp symbioses: Partners in crime
Although these crustaceans are generally found in large aggregations, free-living they have also been shown to exhibit strong symbioses with a variety of other marine organisms. An example of this is the mutualism between the alpheid shrimp Alpheus armatus and the sea anemone Bartholomea annulata situated in the Caribbean sea. This mutualism is based on protection and shelter for the shrimp whilst defending the anemone against predatory fireworm.
Many species of snapping shrimp have also been found to dwell in the intricate canal systems of marine sponges and hard coral. These provide extremely effective protection for the shrimp from predatory fish. In return, the shrimp have been observed to defend their hosts from predatory star stars such as the crown-of-thrones.
Another unusual but well studied mutualism is the partnership formed between the snapping shrimp and different species of goby fish. This cross-species communication is first formed when shrimp construct burrows in sand or rubble, which are colonized by gobies. In exchange, the goby acts as a guard, observing and warning the shrimp of approaching fish or other predators using a series of delicately timed tail flicks or other specialized behaviours. While outside the burrow, the shrimp will maintain constant antennal contact with the goby which allows for fast, effective signalling.
