Scientists try to mimic fish’s suction power

The biomechanics of clingfish could be helpful in designing surgical devices.

Scooting around in the shallow, coastal waters of Puget Sound is one of the world’s best suction cups. It’s called the Northern clingfish, and its small, finger-sized body uses suction forces to hold up to 150 times its own body weight.

These fish actually hold on better to rough surfaces than to smooth ones, putting to shame industrial suction devices that give way with the slightest uneven surface. Clingfish have a disc on their bellies that is key to their tenacious hold. The rim of the disc is covered with layers of micro-sized, hairlike structures. This layered effect allows the fish to stick to surfaces with different amounts of roughness. Many marine animals can stick strongly to underwater surfaces—sea stars, mussels and anemones, to name a few—but few can release as fast as the clingfish, particularly after generating so much sticking power.

Clingfish’s unique ability to hold with great force on wet, often slimy surfaces makes them particularly intriguing to study for biomedical applications. Imagine a bio-inspired device that could stick to organs or tissues without harming the patient. Researchers are also interested in developing a tagging tool for whales that would allow a tag to noninvasively stick to the animal’s body instead of puncturing the skin with a dart, which is often used for longer-term tagging.

Now that they have measured the strength of the suction on different surfaces, the researchers plan to look next at how long clingfish can stick to a surface and why bigger clingfish can stick better than smaller ones.