Researchers have discovered that cuttlefish could play a crucial role in managing future encounters between sharks and humans.
Shark attacks are rare, but when they do occur, they often result in severe injuries. Just days ago, a woman on holiday in Turks and Caicos lost both hands to a shark after attempting to take a selfie with the animal. In 2024, the Florida Museum of Natural History’s International Shark Attack File investigated 88 alleged shark-human interactions worldwide.
Although the likelihood of a shark bite is low, the fear of such encounters remains significant for many people. Certain locations are more prone to shark attacks than others, with Florida consistently ranking as the global hotspot for incidents.
Current methods to prevent shark attacks
Various methods have been employed to reduce the risk of shark attacks, ranging from electronic deterrent armbands to protective nets along popular coastlines. However, none have proven entirely effective. Moreover, developing a solution that does not harm sharks is essential for conservation efforts.
Now, scientists might finally have found a conclusive solution to drive sharks away. Surprisingly, the answer has been hiding in plain sight in nature. The common cuttlefish (Sepia officinalis), a squid-like marine animal that feeds on small fish and crustaceans, appears to produce a natural shark repellent. Cuttlefish secrete a dark ink when threatened, which effectively deters sharks.
How cuttlefish ink repels sharks
“Sharks’ great sense of smell is also their Achilles’ heel”, explains Colleen Lawless, a researcher at University College Dublin. “Cuttlefish ink has found a way to take advantage of their limited number of smell receptors and use it against them.”
The ink contains a high concentration of melanin, which plays a crucial role in repelling sharks. Since sharks rely primarily on their sense of smell to hunt, the melanin in the ink overwhelms their olfactory system by binding to their scent receptors. As a result, sharks are forced to seek out alternative, less overwhelming waters for swimming and hunting. These findings could be instrumental in the development of natural, eco-friendly shark deterrents.
“By leveraging what we’ve discovered, it may be possible to deploy safe and targeted repellents near beaches, aquaculture signs or fishing zones, to minimise encounters between sharks and humans”, said Lawless. “These findings could also support the management of shark movements in sensitive areas. For example, synthetic analogues of cuttlefish ink compounds could be used to keep sharks away from hazardous regions, such as polluted waters or areas with heavy fishing activity, thereby improving their survival as a lot of shark species are classified as endangered.”
If this research leads to the development of effective shark deterrents, it could provide a groundbreaking solution to human-shark conflicts while ensuring the conservation of these vital marine predators.
