| What is a lateral line in fish? | | | | nerve impulses is either increased or decreased, |
| The lateral line is a sense organ that consists of a | | | | depending on the direction of bending. A swimming |
| row of scales that most fish have along their sides, | | | | fish sets up a pressure wave in the water that is |
| extending from their head to tail. Under these scales | | | | detectable by the lateral line systems of other fishes. |
| are a system of fluid-filled canals and specialized cells | | | | It also sets up a bow wave in front of itself, the |
| which transmit vibrations to the brain of the fish. The | | | | pressure of which is higher than that of the wave |
| lateral line helps fish to detect movement and | | | | flow along its sides. These near-field differences are |
| vibration in the surrounding water including predators | | | | registered by its own lateral line system. As the fish |
| and prey. | | | | approaches an object, such as a rock or the glass |
| The lateral line or similar organs in fish such as blind | | | | wall of an aquarium, the pressure waves around its |
| cavefish (which has rows of neuromasts on their | | | | body are distorted, and these changes are quickly |
| heads) are used precisely to locate food without the | | | | detected by the lateral line system, enabling the fish |
| use of sight. Killifish can sense ripples caused by | | | | to turn or to take other actions. Because sound |
| insects struggling on the surface of the water. | | | | waves are waves of pressure, the lateral line system |
| Scientific experiments with Pollack Fish have shown | | | | is also able to detect very low-frequency sounds of |
| that the lateral line is also used for schooling behavior. | | | | about 100 Hz or less. |
| Identification: | | | | An adaptation of the pressure-sensitive systems is |
| Lateral lines are usually visible as faint lines running | | | | seen in the modified groups of neuromasts called the |
| lengthwise down each side, from the area around the | | | | Ampullae of Lorenzini (special sensing organs, forming |
| gill covers to the area near the base of the tail. | | | | a network of jelly-filled canals), which are found in |
| Sometimes parts of the lateral line are modified into | | | | sharks, rays and a few bony fishes. The Ampullae of |
| electro-receptors (biological ability to receive and | | | | Lorenzini are able to detect electrical charges, or |
| make use of electrical impulses), which are organs | | | | fields, in the water. Most animals, including humans, |
| used to detect electrical impulses. | | | | emit a DC (Direct Current) field when in seawater. |
| How the Lateral Line Works: | | | | This is thought to be caused by electrical potential |
| There are receptors in the line, called neuromasts, | | | | differences between body fluids and seawater and |
| each consist of a group of hair cells, these cell hairs | | | | between different parts of the body. An AC field is |
| are surrounded by a protruding cupula (an organ that | | | | also set up by muscular contractions. A wound, even |
| gives an animal a sense of balance). Neuromasts may | | | | a scratch, can alter these electrical fields. |
| occur singly, in small groups called pit organs, or in | | | | Diseases of the Lateral Line: |
| rows within grooves or canals, when they are | | | | Often the lateral line in fish (marine in particular) will |
| referred to as the lateral line system. The lateral line | | | | get infections or degenerate from water conditions. |
| system runs along the sides of the body onto the | | | | Vitamin deficiencies such as Vitamin C and possibly |
| head, where it divides into three branches, two to | | | | Vitamin B complex are one cause of degeneration. |
| the snout and one to the lower jaw. These | | | | Proper feeding of foods high in these vitamins such |
| neuromasts are usually at the bottom of a pit or | | | | as found in Spirulina Algae will help in this case. |
| groove in the fish, which is large enough to be visible. | | | | Proper lighting is another (or lack thereof) is another |
| Skates, rays and sharks usually have lateral-line | | | | parameter for a healthy lateral line in fish. Full |
| canals, in which the neuromasts are not directly | | | | spectrum lighting such as a combination 10,000 K or |
| exposed to the environment, but communicate with | | | | 20,000 K bulb and Actinic (UVA) bulb will help with |
| it via canal pores. The hair cells in the lateral line are | | | | this. The thought is that full spectrum lighting aids in |
| similar to the hair cells inside the others vertebrates | | | | the assimilation of certain vitamins, much as in |
| inner ear (such as the cupula in humans where hair | | | | humans and Vitamin D. |
| cells within the cupula sense rotational acceleration), | | | | An un-grounded aquarium can cause electrical fields |
| indicating that the lateral line and the inner ear share a | | | | that both interfere and degenerate the lateral line in |
| common origin. Some active fish that are constantly | | | | fish. You can test this by using a pocket multi-meter |
| swimming tend to have more neuromasts in canals | | | | on AC volts with a probe in the wall ground and a |
| than on the surface, and the lateral line will be further | | | | probe in the water. To remedy this, you can run a |
| away from pectoral fins, to reduce the noise | | | | wire from your tank or electrical aquarium equipment |
| generated by fin motion. | | | | to a ground in the wall, or simply by running a wire |
| The lateral line system, found in many fishes, is | | | | into a nail or spike driven into the ground outside |
| sensitive to differences in water pressure. These | | | | your home. If connecting directly to the tank, I |
| differences are thought to be due to changes in | | | | recommend using a titanium probe in the aquarium. |
| depth or to the current like waves caused by | | | | For my full article please visit: |
| approaching objects. When pressure waves cause | | | | What is a Lateral Line in fish? The functions and |
| the gelatinous caps of the neuromasts to move, | | | | diseases of the lateral line. |
| bending the enclosed hairs, the frequency of the | | | | |