Touch

February 4, 2025

Water conveys sensory information from mechanical disturbances (movements and sound) over much greater distances than air. Sharks can sense this information via a series of external mechanoreceptors. They can also sense things internally due to the presence of proprioceptors (microscopic sensory cells) found throughout the muscles, joints, digestive system and blood vessels. Sharks have a heightened sense of indirect touch via water displacement around the sharks’ body, this is accomplished by the movement of sensory hair cells which are present in the neuromasts that make up the lateral line system. This system is comprised of a series of canals or channels usually visible to the naked eye as a series of pores or lines, these run from the head all the way to the upper lobe of the tail.

This ability enables sharks to detect prey, predators, other sharks and increases their awareness of any moving object within the water column, as well as enabling the shark to determine the velocity and direction of water flow around its body. The sensory hair cells bend in response to low frequency sounds, vibrations and water movement. Signals are then sent to the medulla oblongata in the brain. The shark will also obtain an orientation on the prey item/object based on the strength of the signal received by the lateral line canals. The lateral line is also used to detect odour through a process referred to as “eddy chemotaxis” meaning the tracking of odour and turbulence simultaneously.