THE WASHINGTON POST — Summer is coming, and soon the beaches will be full of the sounds of people having fun: splashing in the waves, hitting kadima balls, pounding castle-shaped sand.
If you can find a quieter place in the ocean and put your ears underwater, you might hear many other sounds made by the fish.
People have known that fish make sounds since ancient Greece; that’s why they gave fish names like red drum, pigfish or croaker. “They’re based on the sounds these fish make,” said Audrey Looby, a fish sound researcher at the University of Florida. So far, about 1,000 species of fish have been recorded emitting sounds. You can listen to some of them on a website called FishSounds, which Looby will be contributing to soon. His favorite fish is the Gulf toad.
Unlike birds, which make sounds the same way, Looby said fish have evolved to make sounds multiple times in their lifetime. This means that they produce sounds in different ways.
“Basically, they use whatever mechanism works best for them,” she said.
Fish do not have vocal cords, larynx or specialized vocal folds. Thus, one of the most common ways they make sounds is through tribulation – by rubbing two pieces of bony structure together, “like chattering their teeth or rubbing their pectoral fins against other structures to make cricket sounds” , said Looby.
Many others make noise with their swim bladder, which they use primarily to stay buoyant and level in the water. But, Looby said, “some fish have some sort of sound organ attached to that swim bladder, so they can (bang) on it and it sounds like a drum.”
Scientists don’t know how many fish make sounds, but some estimate there could be as many as 22,000 types, or two-thirds of the approximately 34,000 known species. And those are just the sounds fish make on purpose – to call their mates, to let other fish know they’re in trouble, or to communicate that “this is my reef area, listen how hard I sound so why don’t you just swim,” Looby said.
Fish also make passive sounds, such as chewing noises when nibbling on seagrass or seaweed.
According to Looby, active and passive sounds are important because they “convey a lot of information about what’s going on” to fish and researchers. Chewing sounds, for example, let anyone listening know that there is a food source available. And the mating and warning sounds of certain species of fish give scientists information such as “how much diversity is on a reef, where are invasive species, where are endangered species”, a said Looby.
With climate change causing parts of the ocean to warm and become uninhabitable for fish, researchers say fish sounds could help them preserve and restore habitats. For example, there are projects investigating whether broadcasting sounds from a healthy reef into a dying one might encourage fish to come back and populate it. Learning fish sounds “allows us to learn more about (underwater) environments and hopefully deal with them at the same time,” Looby said.