Never have I felt even the slightest desire to slurp down an oyster.  Not once have I looked said bivalve in the eye*, so to speak, and been able to overcome my not inconsiderable revulsion long enough to taste one.  It seems however, that I’m in the minority; many of my dearest friends are completely mad for oysters and eat them in copious quantities whenever they can get their hands on them. 

I bring this up because tasting good (to other people, at least) is a positive characteristic of oysters.  Another positive trait is their uncanny ability to filter dirty nastiness out of rivers and bays, clarifying the water in which they dwell alongside myriad other creatures.  But from an architect’s standpoint, the most superlative characteristic of an oyster has to be its ability to stick itself to fellow oysters and riverbeds, enabling the formation of complex, long-lasting reefs.  These large oyster accumulations provide habitat for other species and protect the coastline from the ravages of storms.  And until recently, human beings had no clear idea exactly how oysters accrete to one another.

Image courtesy www.seattlemet.com

Image courtesy www.climateshift.org

At Purdue University, a research team has conducted experiments to discover the unique properties and composition of oyster cement, a “biomineralized adhesive material for aggregating into large communities.  This cement is an organic-inorganc hybrid and differs from the surrounding shells by displaying an alternate CaCO₃ crystal form, a cross-linked organic matrix, and an elevated protein content … the high inorganic content is exclusive to oysters” (Burkett et al).  If your eyes began to cross while reading the previous quote, have someone slap you on the back, have a shot of espresso, and stay with me. 

Image copyright Burkett, et al. Department of Chemistry and School of Materials Engineering, Purdue University

The researchers cut small sections through oyster shells  that had attached to each other via a small band of gray material that was still visible between the shells.  They pulverized samples of the outer shell, the gray material (oyster cement) and the inner shell of the oysters, and subjected each type of powder to various tests.  They dehydrated it, they treated it with acid, and they used Infrared (IR) spectroscopy among other means to determine that, in fact, the inner shell and outer shell of the oysters were compositionally distinct from the oyster cement.  Further, “the researchers were able to determine that the adhesive contained almost five times the amount of protein than what is found in the shell, as well as both iron and highly oxidized, cross-linked proteins” (Materials Technology).  Aaaand boom goes the dynamite!

What this means is that the oyster adhesive is more inorganic than your typical hydrated, organic glue-like material produced by mussels and barnacles (which are, admittedly, quite strong).  Those adhesives are composed mainly of proteins whereas oyster adhesive consists of about 90 percent calcium carbonate (chalk).  When I looked into calcium carbonate on the interwebs, I found out that the substance is crazy commonplace all over the globe – it’s found in all kinds of shells, most rocks, and even snails. 

It’s thought by the Purdue research team that what makes the oyster cement so effective is the interaction between the calcium carbonate and the small amount of protein that binds everything together.  They’re planning to “investigate the interaction of the different components within oyster cement and use this information for developing new synthetic materials” (Materials Technology).   If they can unravel the inner workings of oyster cement they’ll be able to “provide blueprints for the design of biomimetic materials, aid development of adhesion-inhibiting antifouling surfaces, and illustrate the workings of healthy ecosystems” (Burkett et al).  It’s exciting to think that we could be on our way to developing adhesives for use in medicine and construction that set and hold in wet environments.

*Do oysters even have eyes?? Gross.

Image courtesy www.content.cdlib.org

WU XING:

I am filing oyster cement under water (heh – get it!) and also in the earth category because you can basically make land if you have enough oysters.  The Purdue paper mentioned that some reef structures are “tens of meters deep and several square kilometers in area” (Burkett et al).

Cited:

Burkett, Jeremy R., Lauren M. Hight, Paul Kenny, and Jonathan J. Wilker. “Oysters Produce and Organic-Inorganic Adhesive for Intertidal Reef Construction.”  Journal of the American Chemical Society, 2010. Volume 132, pages 12531-12533.

“Oysters Offer Clues to New Adhesive Materials” Materials Technology @ TMS. 09/23/10.  Accessed 10/05/10.  URL.