Researchers recently put their ears to the sea, and were surprised at what they heard. In the first instance of this officially recorded and studied, scientists have found that fish larvae produce specific sounds that could help them maintain group cohesion even while in the dark.
"Although many adult fishes produce sounds, no one has previously considered that larvae, too, may be sound producers. This is the first study to show that fish larvae have an acoustic repertoire," Claire Paris, of the University of Miami (UM) Rosenstiel School of Marine and Atmospheric Science, said in a statement. “This is a true discovery as it reveals the existence of a communication system for young fish larvae.”
According to a study authored by Paris and her colleagues and published in the journal Biology Letters, fish larvae produce what the researchers are calling “knocks” and “growls” in the range of 200-800 Hz, which is within the hearing range of most adult fish.
Interestingly, the larvae seem to produce these sounds only at night, suggesting that they use the sounds to keep together, even when visibility is low or non-existent.
"The study was setup to record ambient sounds around the drifting arena that might guide the fish larval orientation. It was a fantastic surprise to listen to the recording and hear that the larva itself was emitting sound," Paris explained. "Communication between larvae could allow them to maintain group cohesion, which is critically important for faster swimming, finding navigational signals and settlement cues, and better survival."
"This discovery has important conservation implications as well," added Erica Staaterman, lead author of the study.
Staaterman goes on to explain that as human activity continues to invade marine environments with its own noise, it’s important to understand what kinds of essential communication might be disrupted.