Wild Rays Deliver Electric Jolts to Sharks, Issuing "Back Off" Warnings for the First Time on Record
A groundbreaking study, published in the journal Ethology, has shed light on the defensive mechanisms of electric rays, revealing that they may be particularly effective at deterring large predators such as sharks. The research, initially focused on white sharks' social hunting behaviors, unexpectedly uncovered the electric rays' defensive strategy.
The study, led by Assistant Professor Yannis Papastamatiou from Florida International University, found that electric rays can generate powerful electric shocks as a means of repelling sharks and other potential threats. These shocks, which can reach up to 50 volts, are sufficient to startle and dissuade even large shark predators.
Direct field observations and biologging data, notably from studies around Guadalupe Island, Mexico, have shown that when a large shark (such as a white shark) approaches an electric ray, the ray’s electric discharge causes the shark to suddenly flee. For instance, in one case, a tagged white shark rapidly ascended 20 meters after encountering an electric ray at 50 meters depth, and later, when it returned, it avoided the ray altogether.
The electric discharge appears to be a highly effective natural shark deterrent, significantly reducing predation risk from large sharks and allowing these rays to thrive in high-risk environments. The discovery showcases the incredible defensive traits some animals possess and offers fresh insights into the evolution of defensive traits in marine animals.
The discovery was made during a study on white sharks' social hunting behaviours, but the team's discovery of the electric rays' defensive mechanism was a significant finding. Professor Papastamatiou was surprised by the discovery and waited for more evidence before confirming it, including tiger shark footage. He noted that defensive traits like camouflage, venom, barbs, and spines often do not deter large sharks from eating other species of rays.
The discovery of the electric rays' defensive mechanism is particularly interesting because it provides a unique and effective strategy for some species of rays to thrive in dangerous waters. For example, the Gulf torpedo ray was observed using its nictitating membrane as a defensive strategy against a tiger shark.
The team's findings were supported by footage of the behaviour, which demonstrated the electric rays' ability to deter sharks. The deployment of Customized Animal Tracking Solutions (CATS) biologgers attached to white sharks revealed intriguing data about the electric rays' behaviour, further confirming the effectiveness of their electric discharges as a deterrent.
In summary, the electric discharge of electric rays appears to be one of the most effective natural shark deterrents, significantly reducing predation risk from large sharks and allowing these rays to thrive in high-risk environments. The study offers fresh insights into the evolution of defensive traits in marine animals and highlights the incredible defensive traits some animals possess.
- Assistant Professor Yannis Papastamatiou's study, published in Ethology, found that the electric discharge of electric rays, which can reach up to 50 volts, is a powerful defensive mechanism that deters not only sharks but also other potential threats.
- The study, which initially focused on white sharks' social hunting behaviors, unexpectedly uncovered that electric rays' electric discharge is a strategy that causes larger sharks to flee, as exhibited in the case of a tagged white shark that rapidly ascended 20 meters after encountering an electric ray.
- The discovery of electric rays' defensive strategy offers new insights into the evolution of defensive traits in marine animals, shedding light on the remarkable defensive mechanisms some animals possess, such as the Gulf torpedo ray's use of its nictitating membrane as a defensive strategy.
