The most surprising fact about fishes is that you cannot hear them but they can certainly hear you. Fishes are very well equipped with hearing organs. They do not have a pair of ears projecting outwards as in humans, but there are tiny holes on either side of their head, leading to the inner ear. Since there is no external ear to direct the sound, these ears are probably not as effective as our own. But the fishes have other ways of picking up sounds of vibrations in the water. Along each side of the fish’s body is a line of little holes or pores, which can also pick up vibrations and changes in water pressure and pass on the message to the brain. This line of pores is called the lateral line, and can be seen quite easily. By using this lateral line, a fish can avoid all obstacles when it is extremely sensitive to pressure changes caused by the vibrations of another fish or other objects. A fish’s lateral line contains sensory cells, which provide the fish with all the information in respect of activities going on around it. Teleost fishes such as the catfish that lives in rather muddy water have barbels– long sensitive feelers – on the sides of their mouths. Members of the ‘carp’ family have tiny bones in the head, which are linked to the swim bladder. The swim bladder keeps the fish upright in water and also acts as a sounding board, which can pick up and magnify the feeble vibrations, and then pass them along the bones directly to the inner ear. Now you know how it is possible for the fish to pick up even the feeblest sounds around them.