The teeth of a freshwater crustacean are coated with a wear-resistant, enamel-like layer similar to that on vertebrate teeth. This is an example of convergent evolution in which a biological trait develops independently in separate lineages.

Researchers including Amir Berman at Ben-Gurion University in Beer-Sheva, Israel, and Barbara Aichmayer at the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany, used Raman spectroscopy to analyse the mandibles of Cherax quadricarinatus crayfish. On the surface of the molar teeth, the researchers found a layer of fluorapatite crystals (pictured, white), which are chemically similar to the carbonated hydroxyapatite found in vertebrate teeth.

The results indicate that comparable chewing needs led to the independent evolution of similar tooth structures in species from different lineages.

Nature Commun. 3, 839 (2012)