Everyone knows that adult fish can produce sounds, right? Well, maybe not, but trust us, they do.
But earlier this month, a team from the University of Miami's Rosenstiel School became the first ever -- ever! -- to document that fish larvae, also known as baby fish, can also make noise.
"It's really exciting," said Erica Staaterman, the Ph.D student who led the team. "It's cool to be a part of something that's happening for the first time."
The team's paper, titled, logically, "First evidence of fish larvae producing sounds," was published the journal Biology Letters. Besides Staaterman,it was co-authored by Claire Paris, an associate professor who served as the project's adviser and whose lab provided funding, as well as Andrew Kough, a graduate student.
Staaterman told Riptide that the project was borne of broader research she was doing in 2012. While keeping the fish in the ocean, Staaterman isolated baby gray snappers inside a behavior chamber, then used an audio recording device to see what other sounds were present inside the water. The idea was to explore the acoustics of the snappers' natural habitat, to see how ocean noises that might impact their migration.
"They're out there kind of swimming along," Staaterman said of her subjects. "Doing their thing."
But later, when Staaterman was alone at night in her apartment, listening to the sounds she had picked up from the chamber, she heard loud knock and growl noises that clearly weren't normal ambient ocean sounds. "Oh my gosh!" she thought. "This is really cool. It could be these baby fish."
After months of more experiments, the team was able to verify that, indeed, it was the baby fish who were producing the sounds -- the first time non-adult fish had been proved to make noise. "The knocks are like purring sounds, pretty short, chirpy," Staaterman said. "The growls are longer in duration, lower in pitch."
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Staaterman's hypothesis is that the baby fish, who only produce the noises at night, use the sounds as a way to stick together while navigating at night through the dark of the ocean. After fish eggs hatch in the summer months, Staaterman said, the baby fish can drift in the sea for up to a month, then somehow have to find their way back to the safety of the reef.
"The question is," she said, "how do they find their way back?"