A recent study from researchers at the University of Portsmouth has deemed limpet teeth as the strongest biological material known today. We shed light on the unique properties of this material and how it compares to its predecessor: spider silk.
A New Leader Among Strong Natural Materials
In a previous blog post, we discussed how natural adhesives from mussels and sandcastle worms could be replicated synthetically to create stronger underwater adhesives. The natural adhesives produced by these species were used as a protection mechanism, enabling them to thrive within their habitat. Researchers drew upon these natural substances, mimicking their composition in the laboratory setting to design more durable and reliable adhesives.
Within sea life, researchers at the University of Portsmouth recently discovered another natural material possessing great strength: limpet teeth. Limpets are snails that have a conical-shaped shell and primarily live in saltwater environments. Using atomic force microscopy, the university’s research team studied the mechanical behavior of these teeth. In their study, the team observed that limpet teeth featured a strength potentially greater than that of spider silk, which was previously considered the strongest biological material. Let’s take a closer look at how these two natural materials compare to one another.
Comparing Spider Silk with Limpet Teeth
When you hear the term spider silk, your first thought is probably the silk threads that spiders use to spin their webs (such as the one in the graphic below). Most species of spiders, however, have multiple glands that create these protein fibers (which consist primarily of repeating glycine and alanine block sequences) for varying purposes, from sheltering offspring to catching animals.
While the types of spider silk differ depending on the species, the majority of them are recognized for their tensile strength as well as their elasticity — in fact, some forms of silk can be stretched nearly five times their length at a relaxed state without breaking. The Darwin’s bark spider is noted as producing the toughest type of spider silk among spider species, with toughness that greatly exceeds Kevlar and is double that of other spider silks.
For limpets, having strong teeth is of particular importance, as they are used to scrape over rock surfaces while the snail feeds on algae. Limpet teeth obtain their tensile strength from the presence of a mineral known as goethite, which develops as the limpet grows.
According to the study from the University of Portsmouth, spider silk features a tensile stress of up to 4.5 GPa. When analyzing the tensile strength of the limpet teeth, researchers identified a range between 3.0 and 6.5 GPa. In their analysis, they also found that limpet teeth of varying sizes possessed the same level of strength.
Looking Ahead
In the past, it has proved difficult to extract spider silk naturally and also challenging to reproduce its properties in the laboratory environment. Uncovering the strength of limpet teeth paves the way for the development of even stronger structures with a potentially simpler replication process. By reproducing the fiber structures within limpet teeth, this synthetic material could be used to enhance a number of engineering applications, including boats, race cars, and aircraft carriers.
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