Why Do Fish Have a Lateral Line?

The lateral line is a highly developed sensory organ found on the lateral sides of fish and some amphibians. The lines are divided into two sections, anterior (the part located on the head) and posterior (the longer section, running the rest of length of the body).

  1. Biological Development

    • Lateral lines are a part of the evolutionary history of life on earth. They are a similar in form and function to their counterpart sensory hairs, found on insects.

    Examination

    • A magnified look at lateral line exposes the basic unit of the lateral line, millions of tiny sensitive cells, called neuromasts, (specialized hair and support cells). Scientific studies have revealed the existence of a close evolutionary relationship between the inner sensory human ear hairs and neuromasts in the lateral line.

    Pressure Waves

    • Neuromasts become polarized or hyperpolarized as they detect hydrostatic pressure differences (motion) in the water. The millions of cells work together to relay valuable information, such as temperature, pressure and physiography, about its surroundings. In some species, the cells can detect magnetic or electrical fields.

    Survival

    • The lateral line provides fish with heightened sensitivity to minute vibrations needed for hunting. It may also alert a fish of danger, thus preventing it from becoming the main item on the dinner menu of another predator. Some species of fish have adapted neuromasts and are able to detect magnetic and electrical fields, used for long-range navigation and heightened hunting abilities, respectively.

    Navigation &Schooling

    • The lateral line may work like an echo-locator to assist with navigation and schooling. Pressure waves bounce of objects and other fish creating virtual images to enable fish to swim effectively.