Why do fish have a lateral line organ?
The lateral line organ of the fish is used to perceive water movements. It consists of a long canal in the two sides of the body, usually reaching from the head to the tail. Small canals branch off to the body surface at regular intervals. These end in small holes in a fish’s skin, which can be seen in a line next to each other on either side of the fish’s body. Tiny hair-like sensory cells are located in the side canals and protrude into the main canal.
This allows fish to perceive temperature, pressure and thus also flow. If water moves past the fish on the outside, e.g. due to the swimming movements of the fish, due to currents, due to the flapping fins of another fish or due to reflections from objects, etc., the water also flows through the side channels and thus stimulates the sensory cells, in that the hair extensions from the water to be pushed aside. The hairs transmit their sensations directly to the main nerve in the back.
It is also possible for the fish to recognize a direction. Fish that have no eyes, such as the blind cave tetra, can orientate themselves very well in their surroundings and also recognize obstacles.
The lateral line organ is the most sensitive organ in fish. Disorders of this organ can cause balance problems and other symptoms.