The SNAP, CRACKLE, POP of fish sounds

Did you know, there are over 800 fish species in the world that can purposefully make sounds? Fish make sounds for many reasons, including during feeding, defending or advertising territory, finding mates, courtship and spawning. Sound is important because fishes are good at hearing. In fact, fishes can tell different sounds apart, determine the direction of the sound and, most likely, how far away the sound came from.

Fish, capable of sound production, use different methods to make sounds, including vibrating muscles across their swim bladder, rubbing body parts together (called stridulation), and even farting – scientists cleverly call this mode of sound FRT.

Swim bladder sound production

Locally, probably the best-known sound producers are members of the family Sciaenidae (sigh-EE-nih-dee). Sciaenids have the ability to produce a “croaking” or “drumming” sound and include redfish, trout, black drums, Atlantic croaker and spot. To produce the sound, sciaenids possess special red muscles called sonic muscle fibers that vibrate against the swim bladder. Drumming can be used for a variety of reasons, but most notably it is used for spawning. Other fish species that produce sound this way include toadfish, squirrelfish, searobin and some catfish.

Stidulation sound production

Several catfish species are also able to produce sound using their pectoral fins. To do this, catfish pivot and lock their pectoral fin outward within its pectoral socket (akin to our shoulder joint). The catfish then vibrate their pectoral spine using jerk movements. This produces a series of pulses, as ridges on the pectoral surface rub against the pectoral socket. This process is known as stridulation. Stridulation is used by catfish when they are grabbed by a predator, including us.

Seahorses also use stridulation to produce sound. Well, not all of them – just some of them. Certain seahorse species have two pointed bones on top of their heads – one above each eye. Seahorses rub these two unpaired bones together to produce a clicking sound. They do this during feeding and courtship.

Recently, scientists also discovered that some seahorses growl when disturbed. But scientists don’t think this sound is meant to ward off potential predators. It isn’t loud enough. Rather scientists think the vibration that accompanies the growl is meant to startle predators, giving the seahorse an opportunity to escape.

Undoubtedly, the loudest stridulating fishes in the ocean are the damselfish. These fish make sound by rubbing and snapping their teeth together. Different damselfish species are known to make different sounds. Some are popping. Others are chirping. And one species, the Ambon damselfish, produces a sound that resembles a windshield wiper.

Fast Repetitive Tick sound production

Another way some fish communicate with each other is by forcibly expelling gas from the anal area. This produces bubbles and a high-pitched sound; which scientists call a Fast Repetitive Tick (FRT). Both the Atlantic and Pacific herring produce FRTs.

These fish gulp air from the water surface and then store it in their swim bladder. At night, when they are surrounded by other herring, they release the air through their anal duct. Since herring have a good sense of hearing, scientists believe purpose of the FRT sounds may be to ensure that the fish stay close together.

Sources:
Kasumyan, A.O. Sounds and Sound Production in Fishes, Journal of Ichthyology, 2008;48:11, 981–1030.
Parmentier, Eric, Rui Diogo and Michael L Fine. Multiple exaptations leading to fish sound production, Fish and Fisheries. 2017;18, 958–966.

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