Concrete and Limpets Aren’t So Different After All

Since Patella vulgata, the common limpet, are living, breathing organisms, one would expect them to have almost nothing in common with concrete; however, a recent study conducted by David Taylor, professor of materials engineering at Trinity College Dublin, indicates otherwise.

Common limpets, which you may recognize from trips to the beach (if your local beach is somewhere between the Mediterranean and the Lofoten Islands of Norway), are fascinating little creatures. “They have several features that make them interesting from a biomechanics point of view,” explains Taylor in an article from ScienceDaily. “They have evolved mechanisms for adhering very strongly to … underlying rock and are also equipped with a set of very hard teeth.” Not to mention, “the hard-working creatures quickly patch over small holes [at the apex of their conical shells] with new biological building material from within.” These small holes generally result from impacts with rocks as the limpets are tossed by rough seas. According to the article published in the Journal of Experimental Biology, “it is proposed that the apex [of the limpet shell] acts as a kind of sacrificial feature, which confers increased resistance but only for a small number of impacts.” Still, this self-healing ability is an interesting phenomenon, especially once experiments revealed that the patched shell was as strong as the original, undamaged shell.

Unfortunately, the experiments also revealed that, like concrete, the limpet shells were susceptible to spalling—a surface failure characterized by the flaking off of small bits of material due to mechanisms like impact, corrosion, or weathering—after repeated impacts. Scanning electron microscopy identified delamination, or a separating of the ‘laminated’ layers of the shell, which lead to a loss of material by spalling.

David Taylor concluded that while it is “really interesting that [limpets] are still at risk from spalling weaknesses … spalling is evidently one problem that doesn’t have a perfect solution—whether you are a concrete foreman overseeing a building site or a limpet trying to speedily repair his or her home on the seashore.”

Image credit: Royal Irish Academy