Mechanical factors in the excitation of clupeid lateral lines

• Published in: Proceedings of the Royal Society of London. Series B. Biological Sciences
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1983
• Subjects: Hyperoplus lanceolatus
• Online Access: http://dx.doi.org/10.1098/rspb.1983.0023; https://royalsocietypublishing.org/doi/pdf/10.1098/rspb.1983.0023

The excitation of lateral line sense organs (neuromasts) might be expected to depend on differences of movement between the liquid inside the main lateral line canals (the ones that contain the neuromasts) and the walls of these canals. We have investigated this net movement in relation to events in the water around fish. Liquid displacements inside a given part of a main lateral line canal of the sprat ( Sprattus sprattus (L.)) are, at any one frequency, linearly related to those in the medium (sea water) adjacent to this part. For the parts of the canal system studied, and below about 80 Hz, the ratio of displacement inside the canal to that in the medium falls with frequency, i. e. the displacement inside the canal follows the velocity in the medium. Sea water displacements in a given length of a main lateral line canal system are proportional to the component of the external velocity that is parallel to the canal. For this component the ratio of displacements inside and outside the lateral line approaches unity at around 80 Hz. The behaviour of a lateral line canal is close to that of a straight capillary tube of roughly the same cross sectional area. Displacements in the canal are advanced in phase relative to those in the external medium and these phase advances are a little larger than those found in capillaries. There is very little mechanical coupling between neighbouring parts of the main canals. Since the cupulae of the neuromasts of the sprat lateral line are driven by frictional forces, the stimulus to a neuromast will (below 80 Hz) be proportional to the acceleration of the medium adjacent to the lateral line. Sprats and fish of three other species ( Clupea harengus L., Hyperoplus lanceolatus (Lesauvage), and Trachurus trachurus (L.) have been shown, when suspended in sound fields emitted by pulsating and vibrating sources, to behave longitudinally as rigid bodies. Under many conditions it proved possible to calculate the longitudinal movements of fish from the differences of pressure between snout ...