How do fish hear?

Have you ever wondered why you have to keep very quiet if you want to catch a fish? They don’t have any ears!

Actually, fish can hear quite well. Instead of ears opening to the outside of their heads like we have, fish have ear bones called otoliths inside their heads. When a sound wave passes though the water, the vibrations from the sound wave hit the fish and make the otoliths vibrate so that the fish can hear!

Otoliths aren’t just good for hearing, too. As the fish gets older, the otoliths get bigger, and grow in layers just like the rings on a tree. By counting the layers on an otolith, you can tell how old a fish was!

Fish also have another way of sensing what’s going on around them. If you look closely at the side of a fish, you can see a line travelling all the way down the side. That’s called a lateral line, and it helps the fish to sense vibrations in the water. It can tell a fish where its food it, and warn it if any predators are coming its way. Some are so sensitive that fish deep in the water can sense if a tasty insect lands on the surface. They can even sense noise coming from above the water!

So if you ever want to see a fish in a lake or a stream, the key is to sit very still without making a sound. If you do it long enough, a fish might just come by to say hello!