Why is it kids have such a hard time pulling mussels from the rocky shorelines of holiday resorts the world over? Jonathan Wilker and his colleagues at Purdue University reckon the sticky subject is due to the fact that these shellfish pump iron to make their amazingly strong protein adhesives. The findings could have applications in medicine and industry.

Common blue mussel hanging five (or more) after a night adhering to otherwise non-stick Teflon

The deep-blue saltwater shellfish Mytilus edulis, commonly known as the mussel, has intrigued people for many years not least because of its gastronomic talents but because getting them off the rocks is just so tough. Wilker's team have now found what makes mussels stick - they use iron to produce their super-strong natural glue. The discovery represents the first time a transition metal has been found assisting in the formation of an amorphous biomaterial. According to Wilker's findings, the gelatin-like protein glue is hardened, or cured, by the iron.

	The natural glue these creatures make to anchor themselves to the sea floor has surprising chemical characteristics and could have applications in medicine and industry. (Purdue News Service photo/David Umberger)

"It takes about five minutes for a mussel to make an adhesive plaque, and it uses 20 or more such plaques to anchor itself," Wilker explains, "A mussel can easily establish itself overnight and resist the pull of tides, currents, predators and kicking children." So tenacious are these creatures, they can even stick to Teflon, the non-stick coating that lines pans.

The mussel's tenacity lies in the glue, or plaque, through which each filament in its beard adheres to a surface. The researchers say materials like this one could be used in wound closure, nerve reconstruction, tissue engineering, even to stick broken bones back together without metal pins. The materials may also be used to coat metals to form a rust-proof layer for ships' hulls, that would also prevent shellfish from getting a grip. Now, that would be ironic!

Angew Chem Int Edn, 2004, 43, 448-450;
http://dx.doi.org/10.1002/anie.200352759