Herbert Waite of the University of California, Santa Barbara, was intrigued by the role transition metals such as copper, zinc and iron play in fibers manufactured by marine organisms. Building on previous work that had detected high levels of copper and zinc in two species of worms, he led a team of researchers in a detailed investigation of the 15-inch-long bloodworm Glycera dibranchiata, which is commonly used as bait by fishermen. They determined that the worm's four black jaws (see image) contain the copper-based mineral atacamite, which has an ordered, crystalline structure. What is more, it seems that the jaws' strength and resistance to abrasion are increased further by free copper ions that link chains of amino acids together, the team reports.
Because high doses of copper tend to be toxic, the researchers remain uncertain as to how the worms successfully integrate the metal into their jaws without negative consequences. Copper's benefits, however, seem to be numerous. In addition to increased strength, copper may mediate the activation of the worm's venom during injection, the scientists suggest. In particular, they posit that the mineral may act as a catalyst that converts a benign version of the worm's venom to a toxin as it passes through the fangs. Such a setup could prove useful for designing new forms of drug delivery. Says Waite: "We may be able to synthesize the drug in a precursor form and have that last important step done as part of delivery."