Oct 14, 2022
A scale from the Linea Lateralis (lateral line organ)
Some fishes have a row of tiny scales on each side of their body, which works as a sensory organ, detecting vibrations in water. The little hole in the middle of the scale let the water penetrate under the scale, into a tiny canal which conducts the liquid in contact with the external structure of a sensory cells' group, connected to a nerve. The impulse that the nerve record depends on the pressure of the fluid : it can detect very low pressure variations, which allow the fish to perceive movements of other fishes around or to regulate its own swimming speed.