Cilia allow mussels to stick and release quickly

The way in which mussels attach themselves to surfaces has been studied extensively, because the mechanism could yield an adhesive for wet conditions. That research focused primarily on the chemical bonding mechanism of mussel glue, but the connections between living mussel tissue and the threads with sticky ends that the mussel uses to anchor itself have thus far received less attention. However, mussels are not only capable of adhering firmly – they can also detach rapidly. A group of Canadian researchers now shows in Science how the dynamic interface between the mussel and the glue works.

A large frictional surface area

Mussel glue is a biopolymer secreted by mussels. To anchor itself, a mussel produces a large number of threads from that polymer, all of which are attached to a single main thread, the so-called stem. At the attachment point with living tissue, the mussels have cilia, which they can cause to vibrate via neurons. Because there are so many of these hairs, there is also a very large frictional surface area. This allows the mussel to anchor itself without the need for strong covalent bonds. You could compare it to two brushes being pushed together – they do not simply come apart. But when the mussel sets all those cilia vibrating, the entire connection can release in one go.

‘I am impressed by the work – it is difficult to visualise such a dynamic process, especially in such small creatures,’ says Marleen Kamperman, Professor of Polymer Science at the University of Groningen. ‘We just don’t yet know whether we can do anything with it. It is part of the broader search for adhesives that can release on command. We have been studying how the mussel makes its attachment thread for decades, but the mechanism of detachment is new.’

J. Sivasundarampillai, L. Youssef et al. (2023) Science ‘A strong quick-release biointerface in mussels mediated by serotonergic cilia-based adhesion’ https://doi.org/10.1126/science.adi7401