Animal superglue decoded

An international team of researchers led by Prof. Dr. Georg Mayer, head of the Department of Zoology, and his collaborator Alexander Bär has deciphered the function and structure of the glandular secretion of an Australian stump-footed species. Onychophores, a stump-footed species that is more than 300 million years old, catch their prey with the help of a fast and extremely sticky mucus that the animals shoot from paired, specialized nozzles on their heads.

According to the research, the mucus of the stump-footed species Euperipatoides rowelli consists oftiny, uniformly sized, spherical fat-protein structures. When the mucus is touched, these nanospheres deform due to shear forces and stiffen into microfibers consisting of a tensile protein core and a sticky surface. As a result, the secretion adheres strongly and in seconds to almost any surface. However, if the bio-adhesive is exposed to water for a longer period of time, the polymers dissolve again. As the original nanospheres recede, the secretion could be reused.

"So, to our surprise, we found a kind of reusable animal glue," Mayer sums up. "Our study provides important clues about how recyclable polymers are formed in nature in a previously unknown way. If we understand even better how these physicochemical processes take place, this will open up interesting perspectives, especially in the field of surgical medicine, but also for sustainable industrial polymer production, for example." The researchers' next goal is now to synthetically reproduce the bio-second glue.

The onychophores, translated as claw-bearers, are invertebrates and resemble worm-shaped caterpillars with short legs and paired antennae. From two openings on the so-called mucus papillae next to the mouth, the animals, some of which are up to 22 cm in size, eject a strongly adhesive defensive secretion that is used for defense and to catch prey. They live mainly in the southern hemisphere and around the equator. About 200 species are known and registered so far, but there are probably several thousand. The stump-footed animals live mainly in dead wood or in the chaff layer of the forest floor.