Look closely at a cuttlefish's suction cup and you'll see something strange: hundreds of tiny pillars lining its rim, like the bristles of a brush. Scientists always thought suction cups needed smooth edges to form a tight seal. But the common cuttlefish, Sepia officinalis, is covered in these structures — called papillae — and that's exactly why it grips its slippery prey so well.
A team at Wageningen University & Research in the Netherlands set out to understand how cuttlefish stick to rough, uneven prey. It started, senior author Guillermo Javier Amador told Phys.org, with a simple curiosity: "This study came about from looking at a cuttlefish's suction cup under the microscope, where we noticed it had these microscopic pillars all over the suction cup rim." Cuttlefish mostly eat crabs, shrimp and fish — prey with rough skins — so the team suspected the papillae help the sucker hold on where a smooth rim would fail.
That matters beyond the ocean. Cuttlefish suckers actually generate stronger suction pressures than octopus suckers, and understanding them could lead to better suction cups for real-world tools, from robotics to medical devices.
To test their idea, the researchers bought freshly caught cuttlefish from local fisheries and dissected their arms. They glued each arm to a glass slide and placed it in a small water tank with the suckers facing up. Then they used an automated, custom-built machine called an indenter — a motorized plate with a force sensor — to press against the suckers and measure how hard they hold on. The team made artificial surfaces with different roughness levels and softness, mimicking what cuttlefish attach to in the wild.
Their results were clear: the suckers stuck much better to stiffer surfaces than softer ones, and the papillae played a key role in gripping rough terrain. The researchers even built a mathematical model that predicted how water leaks across the sucker's rim, and it matched their experiments.
Co-first author Brett Klaassen van Oorschot notes that most sucker research has focused on octopuses and clingfish. "We learned from earlier work that cuttlefish suckers worked via a totally different mechanism," he said, adding that in the wild, cuttlefish "could adhere extremely fast to a variety of different prey surfaces."
The study, published in the Journal of the Royal Society Interface, points toward new bio-inspired designs — suction technology that finally works on bumpy, uneven surfaces. For a soft-bodied creature with no hands, the cuttlefish has a grip we're only beginning to understand.