Ever wonder how fish know which way is up? They use several clues:

Inside a fish’s head are tiny balance organs. They contain small crystals called otoliths, which sit on hair cells. When a fish tilts or turns, gravity moves the crystals, which bends the hairs under them. The fish’s brain uses this information to tell which way is up.

Fish can look for:

Fish have a gas-filled sac called a swim bladder.

The fish’s brain uses these changes to help control depth.

Fish have a special sensing system called the lateral line that runs along both sides of their body. It can detect:

It’s like a built-in motion detector that helps fish know where they are, even in the dark!