Glycera dibranchiata is just the kind of creature you don’t want to find in the bottom of your beach bucket. They are called bloodworms because of their translucent skin. Long and venomous, the worms are native to both coasts of North America and have four sharp canines and a somewhat cranky temperament: As they burrow through the sand, they will attack anything they feel nearby.
“They protect their grass very well,” said Herbert Waite, a professor at the University of California, Santa Barbara, who studies the creatures. “I think they’re actually introverted people.”
When dissatisfied, the worms shoot out a peculiar-constructed trunk to grab their prey.
“You can imagine that if your head was a balloon, it would normally be sucked into your body. Then, when you want to eat, you blow it up and bite it and then you suck it back in,” said William Wonderly, a chemist also in Santa Barbara who worked with Dr. Waite to study the creatures. “It affects me a lot. reminiscent of the aliens in ‘Alien’ where they have a small mouth that they shoot out and retract.”
The worms have another trait that is less obvious, but just as strange. Sprouting from specialized cells on their skin, their canines are devilishly hard and made up of just three ingredients, including melanin. Although melanin is one of the pigments behind human skin and hair color, bloodworms somehow make it into a tough material infused with copper, which makes up a whopping 10 percent of fangs by weight. But how the worms carry out the chemical transformation used to be a mystery.
In an article published Monday in Matter magazine, Dr. Wonderly, Dr. Waite and colleagues show that the creatures do it by relying on the third ingredient in the canines, a deceptively simple protein with many talents. The find unlocks a biochemical secret to this unusual creature and shows how nature finds surprisingly simple ways to build complex anatomical features.
A bloodworm’s fangs grow from a series of cells that act as funnels and store the materials for their assembly, said Dr. wonderfully. The team examined the proteins used in these cells and identified one, called a multitasking protein, as an important part 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 it plays a critical role in canine assembly.
The scientists found that the protein catalyzes a reaction to make melanin and recruit copper ions. It then bonds melanin into polymers, assembles itself and melanin into a structure, and uses copper to seal the whole thing together. Essentially, multitasking protein seems to divert melanin from its tendency to form into the blobs you’d see microscopically in people’s hair and skin, said Dr. wonderfully. That makes it something completely different: part of a deadly killing machine that hides in the sand.
Not all the mysteries of the bloodworm have been solved: little is known about how the organism first developed this system and how copper is handled in the worm’s body.
“A big question is how the copper concentrates in the jaws,” said Dr. wonderfully. “To really understand it, you need the baby worms. But because they have a complicated spawning cycle, they are difficult to breed in the lab.”
The team hopes to learn more about how the worms assemble this unusual polymer by studying how the melanin is produced and how the worm builds it from precursors in its body.
“There are so many things that nature has come up with in a very efficient, clever way,” said Dr. wait. “It takes basic science and a childlike curiosity to explore.”