In May 2023, Matteo Santon was filming cuttlefish in the shallow-water reefs around Indonesia. A marine visual ecologist at Bristol University in England, he planned to document the predators’ approach to hunting from the perspective of the prey — essentially, to see what it’s like to be the crab.
He was hoping to see a particular hypnotic camouflage display cuttlefish use while attacking. But the cephalopods had their own innovations to show.
“The first time I saw these hunting displays, it was probably one of the coolest things I’ve ever seen,” Dr. Santon said.
In a series of dives over the next year, he and his team filmed more than 200 cuttlefish hunts, from crab-eye view. In a study published last month in the journal Ecology, the scientists documented four elaborate body patterns the cuttlefish used, including what appeared to be imitations of drifting leaves or corals. The cuttlefish displays may somehow hack the visual system of their prey, which may mask their movement or convince the crabs they are harmless flora and fauna, rather than wily predators soon to end their lives.
Cuttlefish are masters of deception. Much like their octopus cousins, the animals have skin filled with pigment-loaded cells and piston-like muscular pumps, which they use to alter their color and texture. They can camouflage almost instantaneously to hide from predators, blending into the seafloor, for example, or disguising themselves as rocks or algae. In laboratories, scientists have also observed some of these sophisticated behaviors as cuttlefish hunt. But this hunting ability has seldom been studied in the wild.
Using a GoPro camera, a plexiglass plate and live crabs, the researchers filmed the Broadclub cuttlefish around the islands of Kri and Mansuar in eastern Indonesia. In all instances, when within several feet of the crab, the cuttlefish took on one of four forms described in the study using names that evoke fighting techniques.
In one form, passing stripe, cuttlefish turn gray and pass rhythmic black stripes down their body, which the researchers suggest may be a nonthreatening movement to mask their looming presence.
As the leaf, cuttlefish become a pale green and twist slowly, perhaps akin to a mangrove leaf drifting in the water column.
During branching coral, they adopt coralline patterns and raise kinked arms, creating an appearance similar to staghorn coral.
For the pulse technique, the cuttlefish pull their arms upward into a cone and pulse black waves toward the tips. This may mimic something nonthreatening, the researchers suggest, such as a small fish.
The movements of the patterns may “give the cuttlefish more time as it approaches,” said Trevor Wardill, a sensory neurobiologist from the University of Minnesota. He added that he wonders “how evolution built such a system, as even young animals can do this.”
The cuttlefish used the branching coral technique 12 percent more often when hunting purple mangrove crabs, which were better armed and armored than other crabs. This hints at the possibility that they are tailoring displays to specific prey.
“The underlying question is to what extent these are innate responses, or if they’re able to flexibly mix different components of the behaviors and learn about different situations — whether it’s a higher level form of cognition,” said Daniel Osorio, a neuroscientist at the University of Sussex in England.
Sometimes the cuttlefish quickly switched between disguises — a tactic cephalopods use to deter predators. As cuttlefish must move to hunt, they expose themselves, Dr. Osorio said, and the displays may be as much to confuse predators as their prey.
“Whether or not the cuttlefish are learning to adjust their predatory displays, they still reflect an impressive degree of neural processing power,” said Rachel Blaser, a professor of neuroscience, cognition and behavior at the University of San Diego. “It represents an extremely sophisticated level of motor coordination.”
The findings also suggest cuttlefish possess a larger repertoire of displays than studied in the lab: Perhaps captive cuttlefish haven’t felt the need to hoodwink food that is already dead, Dr. Santon said.
Or perhaps they’re just a little bored.
“I’m always out in the wild,” he said. “And I think animals should be looked at in the wild.”
