Understanding the biomechanics of clingfish could assist in designing devices and instruments to be used in surgery and even to tag and track whales in the ocean, say scientists.
The team of researchers at the University of Washington’s Friday Harbor Laboratories on San Juan Island are studying this fish to understand how it can summon such massive suction power in wet, slimy environments.
Clingfish, belonging to the Gobiesocidae family, are typically small, tadpole shaped fish which possess pelvic fins, modified into a strong suction disc. This disc allows clingfish to maintain a firm attachment to the rocky surfaces off intertidal zones, withstanding strong currents and turbulent wave action. There are about 100 species of clingfish 1 in our oceans, with the Northern clingfish being the primary focus of the team’s research.
“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 at Friday Harbor Labs. Ditsche presented her research on the sticky benefits of clingfish last month in Nashville at the Adhesive and Sealant Council’s spring convention in a talk, “Bio-inspired suction attachment from the sea.”
The specific mechanism for the strong adhesion of clingfish has been shown to result from the hierarchically structured microvilli (tiny hairs similar to those found on gecko and spider feet) around the edges of the adhesive disc. These discs have proved to exhibit stronger adhesion than man-made suction cups. When you pull on a suction cup, its sides slide inward preventing a seal being formed on rough surfaces; however, the clingfish’s microvilli induce high friction to prevent slipping, as well as the disc’s flexibility and microvilli helping seal its edges to rough surfaces, preventing liquids from leaking in and disrupting the adhesion 2.
Lead researcher Adam Summers believes the utilisation of the clingfish’s suction disc mechanism in biotechnology could prove valuable in many different fields.
“The ability to retract delicate tissues without clamping them is desirable in the field of laparoscopic surgery,” Summers said. “A clingfish-based suction cup could lead to a new way to manipulate organs in the gut cavity without risking puncture.”
The team are also interested in developing a tagging tool for whales that would allow a tag to non-invasively stick to the animal’s body instead of puncturing the skin with a dart, which is often used for longer-term tagging.
It is true that there are a variety of marine animals that posses the ability to adhere firmly to underwater surfaces including starfish, mussels, barnacles, limpets and anemones, to name a few. Scientists are already trying to replicate the adhesion mechanisms of mussels for use in man-made adhesives, however this form of adhesion can’t be turned on and off as needed, limiting its potential applications. It is the rapid adhesion and release exhibited by clingfish that makes them a unique and exciting prospect for biotech, in addition to their impressive strength of adhesion – being able to support up to 150 times their own body weight when lifted 3.
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. They also want to understand why bigger clingfish can stick better than smaller ones, and what implications that could have on developing materials based on their properties.
Photo Header Credit: Northern Clinfish’s suction disc – Petra Ditsche, UW