Claire Corlett

Fish Food, Fish Tanks, and More
A Very Sticky Fish…

A Very Sticky Fish…

(water bubbling) (relaxing hip hop beat) The ocean is a wonderful and mysterious place. The intertidal zone, the stretch of sea exposed at low tide, and covered at high tide, is home to a rich abundance of life. But imagine trying to live here yourself. As beautiful as it is, the intertidal zone is also full of scary stuff. Powerful crashing waves, slippery, jagged rocks, predators of all shapes and sizes. If you were a fish, how would you deal with these headaches? Well, the northern clingfish has evolved a clever strategy for living among the extremes of the rocky intertidal zone. Let’s just say that this is one sticky fish. The clingfish, found in the waters of the pacific northwest, is named for its adhesive disk, a sort of suction cup on its belly capable of sticking to all kinds of surfaces. Smooth or rough, clean or fouled, dry or submerged in water. You can see why the suction cup comes in handy in the turbulent, wave-swept rocky intertidal zone. Here, at the University of Washington’s Friday Harbor Laboratories, Professor Adam Summers and his colleagues have been studying the clingfish to found out just how sticky its suction cup is, and how it works. The researchers started by putting the clingfish toe-to-toe with a man-made suction cup, sticking each to different kinds of surfaces. They discovered that the artificial cup only adhered to the smoothest of surfaces, but failed to stick to anything remotely rough. The clingfish, on the other hand, stuck to all kinds of surfaces, even those as rough as the coarsest sandpaper. Strangely enough, the clingfish seemed to prefer the gritty surfaces to smooth ones. So how does this seemingly magical suction cup work? Unlike the smooth rim of an artificial suction cup, the rim of the clingfish’s disk is actually made up of grids of tiny fingers. Guess what’s on the tips of those fingers? Tinier fingers. And on the tips of those fingers? Even tinier fingers. These descending levels of tiny fingers are called microvilli, and they allow the disk to interdigitate with rough surfaces, reaching into every nook and cranny, and creating a tight seal that won’t slip. It turns out that clingfish prefer grittier surfaces because its suction system depends on friction. With less friction between the microvilli on the surface, the edge of the disk tends to buckle inward. You might be asking “How can we make our “suction cups more like the ones clingfish have?” Well, scientists have been asking the same question, and brainstorming some solutions. Imagine being able to use a clingfish suction cup for surgery, rock climbing, or whale tagging. Can you think of any cool new uses for the clingfish’s suction cup? With a talent like this, the clingfish is sure to be sticking around the intertidal for awhile.

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