An odd little fish that attaches tightly to rocks could play a role in developing underwater suction cups that won’t let go even under the harshest conditions. I found the video amusing, but there is a serious side to this discussion as well.
University of Washington scientists studying biological attachment say the northern clingfish can hold up to 150 times its own weight, thanks to a growth on its underside that works like a suction cup. Unlike a standard suction cup, however, the clingfish’s sucker works even better on rough surfaces. The researchers are just beginning to imagine the possible applications for humans.
One idea is to develop a super suction cup that could attach a satellite transmitter to a killer whale or other marine mammal. The current method for long-term attachment is to use a sharp barb to penetrate the skin. Standard suction cups are commonly used for short-term monitoring with small instruments, but they tend to fall off quickly.
Suction-cup attachments could be developed for laparoscopic surgery, allowing doctors to move organs around without risk of puncture. Other applications could be anywhere a temporary tight bond is needed under wet conditions, such as the wall of a shower or swimming pool.
“Northern clingfish’s attachment abilities are very desirable for technical applications, and this fish can provide an excellent model for strongly and reversibly attaching to rough, fouled surfaces in wet environments,” said Petra Ditsche, a postdoctoral researcher working with Adam Summers and his team at Friday Harbor Labs in the San Juan Islands. (See UW news release.)
In April, Ditsche found an interested audience at a meeting of the Adhesive and Sealant Council, which studies, promotes and markets various forms of attachment.
So how are clingfish able to hold on so tightly? The secret lies in the tiny hairlike structures called microvilli formed in layers around the suction-cup growth on their bellies. The microvilli help form a tight seal on rough surfaces, and they flex to maintain the seal even when wiggled back and forth. A standard rubber or plastic suction cup can rapidly lose its seal from distortion or movement, which allows air or water to seep underneath.
For a detailed discussion about biological attachment of all sorts, check out a paper by Ditsche and Summers called “Aquatic versus terrestrial attachment: Water makes a difference” in the Beilstein Journal of Nanotechnology.
About 110 species of clingfish have been identified, and the northern clingfish is found from Mexico to Alaska.