These blood worms grow copper fangs and have bad attitudes

Glycera dibranchiata is exactly the kind of creature you don’t want to find at the bottom of your beach bucket. They are called bloodworms for their translucent skin. Long and venomous, the worms are native to both coasts of North America and have four sharp fangs and a somewhat grumpy temperament: as they burrow into the sand, they attack anything they feel nearby.

“They are very protective of their territory,” said Herbert Waite, a professor at the University of California, Santa Barbara, who studies the creatures. “I think they’re basically introverts.”

When disaffected, the worms launch a proboscis of peculiar construction to grab their prey.

“You can imagine, if your head were a balloon, normally it gets sucked into your body. So when you want to eat, you inflate and bite and then suck it back in,” said William Wonderly, a chemist also in Santa Barbara who has collaborated with Dr. Waite to study the creatures. “It reminds me a lot of the aliens from ‘Alien’ where they have a little mouth that they shoot and retract.”

Worms have another, less obvious, but equally strange feature. Its fangs, which sprout from specialized cells in its skin, are fiendishly tough and made up of just three ingredients, including melanin. Although melanin is one of the pigments behind human skin and hair color, earthworms somehow turn it into a tough copper-infused material, which makes up about 10% or more of prey by weight. But how the worms carry out the chemical transformation used to be a mystery.

In an article published Monday in the journal Matter, Dr. Wonderly, Dr. Waite and colleagues revealed that the creatures do this by relying on the prey’s third ingredient, a seemingly simple protein with many talents. The discovery reveals a biochemical secret of this unusual creature and highlights how nature finds surprisingly simple ways to build complex anatomical features.

A bloodworm’s fangs grow from a set of cells that function like funnels, storing the materials for their assembly, Wonderly said. The team examined the proteins used in these cells and identified one, called the multitasking protein, as an important component of the final product. This protein, they report in the new paper, is primarily made up of just two amino acids, a small number but plays a crucial role in prey assembly.

Scientists found that the protein catalyzes a reaction to create melanin and recruit copper ions. Then it binds the melanin into polymers, assembles itself and the melanin into a structure, and uses the copper to seal it all in. Essentially, the multitasking protein appears to stave off melanin from its tendency to form in the bubbles you’d see microscopically in human hair and skin, Wonderly said. This allows him to become something else entirely: part of a lethal killing machine that lurks in the sand.

Not all of the blood worm’s mysteries are solved: little is known about how the organism first developed this system and how copper is handled within the worm’s body.

“A big question is how copper is concentrated in the jaws,” Wonderly said. “To really understand, you would need the baby worms. But because they have a complicated spawning cycle, they are difficult to grow in the laboratory.”

The team hopes to learn more about how the worms assemble this unusual polymer by tracking how melanin is produced and how the worm builds it from precursors within its body.

“There are so many things that nature has figured out how to do in a very efficient and smart way,” Waite said. “It requires basic science and a childlike curiosity to find out.”

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