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Teeth are self-sharpening: American beaver

The teeth of beavers self-sharpen because their inner surface is softer than the outer enamel and wears away faster to create a sharp edge.

"Plant-eaters have to have particularly good teeth. Not only do they use them for very long periods but the material they have to deal with is often very tough. Rats, like other rodents--squirrels, mice, beavers, porcupines--cope with that problem by maintaining open roots to their front gnawing teeth, the incisors, so that they continue to grow throughout the animal's life compensating for wear. They are kept sharp by a simple but very effective self-stropping process. The main body of the rodent incisor is made of dentine, but its front surface is covered by a thick and often brightly coloured layer of enamel which is even harder. The cutting edge of the tooth thus becomes shaped like a chisel. As the top incisors grind over the lower ones the dentine is worn away more quickly and this exposes the blade of enamel at the front keeping a sharp chisel edge." (Attenborough 1979:246)

"Like all rodents, beavers have self-sharpening incisor teeth that never stop growing. The outer surface is protected by tough enamel, but the inner surface is softer and wears away as the beaver gnaws, creating a sharp, chiseled edge." (McKay et al. 2004:222)
About the inspiring organism
American beaver
Castor canadensis Kuhl, 1820
Common name: beaver

Habitat(s): Forest, Wetlands
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Some organism data provided by: ITIS: The Integrated Taxonomic Information System
Organism/taxonomy data provided by:
Species 2000 & ITIS Catalogue of Life: 2008 Annual Checklist

Threat Categories LONG_LC IUCN Red List Status: Least Concern

Bioinspired products and application ideas

Application Ideas: Self-sharpening tools.

Industrial Sector(s) interested in this strategy: Manufacturing, tools

George McKay; Fred Cooke; Stephen Hutchinson; Richard Vogt; Hugh Dingle. 2004. The Encyclopedia of Animals: A Complete Visual Guide. Berkeley: University of California Press. 608 p.
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Attenborough, D. 1979. Life on earth. Boston, MA: Little, Brown and Company. 319 p.
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