Buzz
At first sight, the cuttlefish appears to be an easy target—soft, compact, and seemingly vulnerable. However, this creature is far from defenseless.
Similar to octopuses and squids, the cuttlefish lacks an external shell, pushing it to develop ingenious defense mechanisms. Researchers in biology and material science are fascinated by its ability to deceive. By manipulating pigment and light-reflecting cells, it can alter its color and even produce intricate patterns on its skin. Additionally, it can change its shape, allowing it to blend seamlessly into its environment in an instant.
While these dazzling tactics work against predators that rely on vision, they are ineffective against those that hunt using scent, touch, or electrosensing.
This phenomenon is more widespread than many realize. All living organisms emit some level of electrical energy. While creatures like the electric eel generate a substantial charge, most beings, including humans, produce a subtle electrical field as they go about their daily lives.
The number of animals capable of detecting electrical fields is continually expanding, particularly among aquatic species. Sharks lead the pack, boasting electrosensing abilities 10,000 times more acute than any other known creature.
Sharks have a diverse diet, and one of their preferred meals is the cuttlefish. At first glance, the cuttlefish appears defenseless, but appearances can be misleading. Recent studies reveal that cuttlefish can suppress their electrical fields, making them almost undetectable to predators.
This discovery stems from the work of Duke University biologist Christine Bedore, who specializes in studying electrosensing in marine life. Bedore discovered that the common cuttlefish (Sepia officinalis) emits an extremely faint electrical field, approximately 75,000 times weaker than a single AAA battery. However, even this minimal field could still attract a shark’s attention.
To observe how cuttlefish react to predators, Bedore placed an iPad screen against a cuttlefish tank, displaying videos of approaching crabs, sharks, and groupers—another known predator of cuttlefish.
The crab silhouette, posing no danger, failed to alter the cuttlefish’s behavior. However, when the shapes of sharks or groupers appeared, the cuttlefish in the tank became motionless. Its breathing rate decreased, and it appeared to use its arms to shield certain parts of its body.
During the experiment, Bedore monitored the cuttlefish’s electrical emissions. See the results for yourself:
The cuttlefish’s strategy significantly reduced the intensity of its electrical field. By concealing its siphons with its arms, it managed to diminish its electrical output by up to 89 percent.
In the next stage of the research, Bedore and her team allowed real sharks to interact with a simulated cuttlefish in two states: relaxed and frozen. The relaxed cuttlefish was not only visible but also highly enticing, prompting sharks to bite the equipment. In contrast, the subdued electrical field of the frozen cuttlefish resulted in 50 percent fewer shark bites.
Bedore and her team shared their findings in the December 2 edition of the Proceedings of the Royal Society B.
