Mussels have an incredible ability to cling to wet surfaces. It's an ability that scientists are trying to replicate for use in man-made adhesives. That adhesion can't be turned on and off as needed, however, limiting its potential applications. That's where the Northern clingfish comes in. It can suck onto rough, slimy surfaces, supporting up to 150 times its own body weight when lifted. That said, it can also just let go and swim away whenever it wants. Scientists from the University of Washington now understand how it's able to do so, and are looking at applying the principle to fields such as surgery and whale-tracking.

The clingfish is about the length of a person's finger, and is found abundantly along the North American Pacific Northwest coast. Its pelvic and pectoral fins are fused together, to form a suction cup-like disc on its underside.

One of the problems with traditional rubber suction cups, however, is that their bottom surface is very smooth and uniform. This means that when they're pressed up against rough surfaces such as rocks, they can't form a seal.

By contrast, the underside of the clingfish's disc is covered with tiny hair-like structures, arranged in layers. These flexible hairs are able reach down into minuscule nooks and crannies on uneven surfaces, finding purchase at different levels and angles. Similar to the case with gecko feet, clingfish are able to release that hold simply by relaxing the disc, which has an elastic consistency.

It is now hoped that a similar microstructure could be used to attach tracking devices to whales – such gadgets currently often have to be secured using darts that puncture the animals' skin. The technology could also be used in laparoscopic surgery to retract delicate tissues, which can be damaged when traditional clamps are used.

The research is being led by Prof. Adam Summers and postdoctoral researcher Petra Ditsche.

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