Bloodworms possess a fascinating biological adaptation: jaws that contain a significant amount of copper. While it might sound like they have pure metal teeth, their jaw structures are more complex, incorporating copper into a unique biomineralized material. This integration of an unusual element into their anatomy is a notable natural engineering feat.
Meet the Bloodworm
The marine bloodworm, Glycera dibranchiata, is a segmented worm typically found burrowing in the muddy sediments of intertidal zones. These creatures can grow up to 14 to 15 inches (35 to 37 centimeters) in length, and their reddish appearance, which gives them their common name, comes from the hemoglobin in their translucent bodies. They are predatory invertebrates, actively hunting other small marine organisms.
Bloodworms capture prey by everting a specialized muscular tube called a proboscis, which houses four black, hollow jaws at its tip. Once they latch onto their victim, these jaws inject a paralyzing venom. They are known for their aggressive nature and will readily use their jaws in self-defense or during encounters with other worms.
The Unique Composition of Their Jaws
Bloodworms do not have conventional “copper teeth” but rather jaws composed of a distinctive biomineralized composite material. This material incorporates protein, melanin, and a significant concentration of copper, making up to 10% of the jaw’s total weight. This level of copper integration is considered the highest found in any known animal structure. The specific copper-containing mineral identified in their jaws is atacamite, a copper chloride mineral.
This is an unusual choice for biomineralization, as most hard biological structures in nature are formed from calcium, silicon, or iron-based minerals. The bloodworm synthesizes these unique jaws by harvesting copper from marine sediments in their environment. A specialized multi-tasking protein (MTP) plays a crucial role in this process, recruiting copper ions and facilitating their incorporation. This protein also helps convert an amino acid derivative, DOPA, into melanin, which then integrates with the copper and protein to form the robust jaw material.
The Biological Advantage of Copper
The copper-rich composition provides significant functional benefits to the bloodworm, enabling their predatory lifestyle and survival in their abrasive habitat. These jaws are exceptionally strong, durable, and resistant to wear, which is essential because bloodworms only form their jaws once during their entire lifespan, which can last up to five years. The jaws must withstand continuous use for capturing prey and injecting venom.
The hardness and stiffness of the jaws are enhanced by the copper, allowing them to pierce the tough exoskeletons of their prey efficiently. Copper ions also help create a tightly networked structure between the proteins and melanin, contributing to the material’s integrity. Beyond predation, the copper content aids in resisting abrasion from sand and gravel as the worms burrow through sediment. The jaws’ wear resistance, comparable to tooth enamel, highlights this remarkable adaptation.