The murky ink from cuttlefish (Sepia officinalis) could help deter sharks from hunting near where people are swimming. After a team at University College Dublin created models of the olfactory systems of several species of sharks, they found that the bioluminescent cephalopod’s ink might overwhelm the sharks’ heightened sensitivity to odors. The findings are detailed in a study recently published in the journal G3: Genes, Genomes, Genetics.
“Understanding how prey species like cuttlefish have evolved to exploit specific vulnerabilities in predators like sharks enriches not only our understanding of marine ecosystems but provides inspiration for conservation tools rooted in natural processes,” study co-author and biologist Colleen Lawless said in a statement.
Sharks are top predators, in large part due to their six highly refined senses: electromagnetism, sight, touch, taste, hearing, and smell. Many species can smell blood from up to a quarter mile away and once they detect the source of the blood, they can use their impressive jaws and muscles to rip their prey apart. However, their heightened sensitivity to smells might be their Achilles’ heel.
In the new study, a team recreated a three-dimensional model of a cloudy catshark’s (Scyliorhinus torazame) and great white shark’s (Carcharodon carcharias) olfactory system in a lab. When they tested it against cuttlefish ink, the team found that melanin–its major component–has a molecular structure that allows it to latch onto the smell receptors. The melanin disrupts the sharks’ sensory perception and could cause them to avoid an area of where the ink has been dispersed. This binding effect also could extend to all shark species, since they generally have the same set of smell receptors.
[ Related: Cuttlefish have amazing eyes, so robot-makers are copying them. ]
According to the team, the effectiveness of cuttlefish ink as a natural shark deterrent suggests it could be used in conservation, marine management, and human-shark coexistence. Some of the current non-lethal methods for keeping sharks away from beaches are gill nets and drumlines. These methods are invasive and not only catch large sharks, but their ropes will often trap rays, dolphins, turtles, and whales.
“By leveraging what we’ve discovered, it may be possible to deploy safe and targeted repellents near beaches, aquaculture sites, or fishing zones to minimize encounters between sharks and humans,” said Lawless. “These findings could also support the management of shark movements in sensitive areas.”
According to Lawless, synthetic cuttlefish ink compounds could be made and distributed in water to keep sharks away from hazardous places. These include areas with heavy fishing activity or polluted waters, which could help protect shark species that are threatened or endangered by keeping them out of harm’s way.
