The lateral line appears as a faint line of scales on each side of a fish that extends from the gills to the tail.
The lateral line senses vibrations that allow a fish to detect movement and pressure changes. This helps fish locate predators and prey, orient themselves in water currents, and avoid collisions.
The lateral line contains mechanoreceptors, called neuromasts, that are made up of a group of hair cells that are similar to those found within the inner ear of vertebrates. They are most often arranged in rows on or just below the surface of the skin.
In many fish, the neuromasts are embedded in a mucus-filled structure called the lateral-line canal. The canal is located just below the skin, and only the neuromast receptors extend into the canal.
The nature of a fish's lateral-line system depends on the circumstances of its life. Fish that are active swimmers often have more neuromasts in canals than on the surface. The lateral-line is also important for fish with little or no eyesight because it allows them to locate food.
Article Written By Richard Hansen
Richard Hansen grew up and currently resides in Minnesota. He graduated from Dartmouth College and has traveled extensively in Africa and South America, including the Amazon jungle. He has worked as a wilderness guide in Yellowstone and northern Minnesota, and written for Fur-Fish-Game, Dartmouth Alumni Magazine and RascalHansen.com.