Some Fish Hear with Their Bones and Communicate in an Unusual Way

We love to scratch the ears of our pets, and when we think of animal ears, we think of fur-covered appendages that are small, large, pointy, or floppy. However, animals that live in water have (necessarily) adapted our concept of ears to fit their hearing and communication needs.

Meet the Clupeidae family of fish—herrings, sardines, and shads. Fish, in general, don’t have outer ears but do have inner ears. Most fish receive sounds underwater that vibrate their inner ears. But the Clupeidae do things a little differently. They use their swim bladder, an air-filled organ that helps them float. Their swim bladder is connected to their inner ears via tiny bones, making their sound detection superior. This connection between the swim bladder and the inner ears amplifies and focuses on sound underwater, giving them an advantage in detecting their predators and communicating with one another, even over long distances.

The Clupeidae fish have a unique way of communicating with one another. They use their swim bladder to release controlled gas, which is high pitched. Scientists refer to this behavior as “Fast Repetitive Ticks” (FRTs). Only other fish with this unique hearing system can detect these gas bubbles.

Unfortunately, the oceans are becoming noisier and the Clupeidae, with their supreme hearing systems, are distressed. Migration, school formation, predator detection, and more are all being affected. Protecting them ensures a food source for larger fish, whales, sea birds, and humans. But this tiny fish is so much more than food. They help maintain a balance in ocean food, hear with pinpoint accuracy with a unique system, and communicate with others underwater- with sounds humans cannot hear.

Reference

Secret. (2025, October 7). The Fish That Hears with Its Bones. Earth.