Sharks possess an extraordinary ability to navigate and hunt in water, largely due to their advanced auditory and sensory systems. Although they lack visible external ears, their hearing is exceptionally acute, enabling them to detect a wide range of sounds that are imperceptible to humans.
Embedded on either side of a shark’s head are two inner ears, linked by a channel to tiny openings on the surface. These ears contain the fundamental elements found in the auditory systems of most vertebrates, including humans. Central to their hearing are the maculae, clusters of nerve cells sensitive to sound vibrations.
Remarkably, sound travels much faster and farther in water than in air, and sharks are adept at picking up these sound waves. Their hearing is intricately connected to the lateral line system, a feature discussed in the context of their tactile sense. When any movement or noise occurs underwater, it generates sound waves that are swiftly detected by the sharks’ inner ear nerve cells.
Research indicates that sharks can hear frequencies ranging from 10 Hz to 800 Hz, a spectrum different from the human range of 25 Hz to 16,000 Hz. Sharks excel at detecting low-frequency sounds, such as those produced by injured or feeding fish, giving them a significant advantage in locating prey.
Apart from aiding in hunting, sharks’ auditory receptors are crucial for discerning the direction and speed of sound sources in water.
Adding to their impressive sensory repertoire is the shark’s “sixth sense” – electroreception. This ability enables sharks to perceive minute electrical fields generated by living organisms. This sixth sense is facilitated by electroreceptors called the ampullae of Lorenzini, named after the anatomist who first described them. These are jelly-filled pores located around the shark’s head and lower jaw, connected to nerves that can detect the faintest electrical signals.
All animals, including humans, emit electrical impulses through muscle activity and interaction with the Earth’s magnetic fields. While these electric currents are a normal part of daily life, they become key signals for sharks in the aquatic environment. The strength of these electric fields diminishes with distance, making the shark’s electroreceptive sense most effective at close range.
Together, these advanced hearing and electroreception capabilities make sharks one of nature’s most adept predators, finely tuned to the subtleties of their underwater world.