Worm's teeth conceal odd mineral material. (Materials Science).

The bite of the common bloodworm, a popular fish bait, hides more than nasty venom. The worm's unusual teeth contain the first known example of a copper-containing mineral in a living organism, researchers report in the Oct. 11 Science.

The worm's version of this strong, lightweight copper chloride mineral, known as atacamite, may serve as a model for the design of new synthetic materials, says coauthor Galen D. Stucky of the University of California, Santa Barbara.

Laboratory tests on the jaws of the bloodworm Glycera dibranchiata revealed that atacamite's organization makes them durable and flexible. The mineral forms within a protein matrix as fibrous structures about 50 nanometers wide and 500 nanometers long.

Up to 5 percent of the jaw's weight is copper, which is also present there in an unmineralized form, says Stucky. The researchers don't know why such high concentrations of copper aren't toxic to the worm or why the worms have copper in their jaws. They might use the metal to activate their venom or prevent tooth decay, the researchers suggest.

Stucky speculates that a synthetic material based on the worm's teeth might one day serve as an antifouling coating for ships' hulls.--J.G.