New species of worm discovered in the Mediterranean with eyes from another world

A new species of bristle worm has amazed scientists for having an advanced vision system with enormous eyes, for such a primitive creature.

Their eyes are so sharp that they can be compared to those of mammals and octopuses. Experts from the University of Copenhagen and Lund University who have investigated it suspect that these marine worms may have a secret language, which uses ultraviolet light that only their own species see.

The Vanadis bristle worm has eyes as big as millstones, relatively speaking. In fact, if our eyes were proportionally as big as those of this Mediterranean marine worm, we would need a large, sturdy wheelbarrow and muscular arms to carry the extra 100kg.

Altogether, the worm’s eyes weigh about twenty times more than the rest of the animal’s head and appear grotesquely out of place on this tiny, transparent sea creature. As if two giant bright red balloons had been tied to his body.

Vanadis bristle worms, also known as polychaetes, can be found around the Italian island of Ponza, west of Naples. These worms are nocturnal and are out of sight when the sun is high in the sky. So what are they for?

Neurobiologist and marine biologist Anders Garm from the Department of Biology at the University of Copenhagen tried to find out. He was hooked when his colleague Michael Bok from Lund University showed him a recording of the bristle worm.

“Together, we set out to unravel the mystery of why a transparent, almost invisible worm that feeds in the dark of night has evolved to acquire enormous eyes. As such, the first goal was to answer whether large eyes give the worm good vision,” says Michael Bok, who, along with Garm, is the author of a new research paper that does just that, in a statement.

It turns out that Vanadis’s vision is excellent and advanced. Research has shown that this worm can use its eyes to see small objects and track their movements.

“It’s really interesting because an ability like this is normally reserved for us vertebrates, along with arthropods (insects, spiders, etc.) and cephalopods (octopuses, squid). This is the first time such an advanced and detailed view has been demonstrated. Beyond these groups. In fact, our research has shown that the worm has excellent vision. “Its vision is on par with that of mice or rats, despite being a relatively simple organism with a small brain,” says Garm.

This is what makes the worm’s eyes and extraordinary vision unique in the animal kingdom. And it was this combination of factors about the Vanadis bristleworm that really caught Garm’s attention. The researcher’s work focuses on understanding how simple nervous systems can have very complex functions, as was undoubtedly the case in this case.

For now, researchers are trying to figure out what caused the worm to develop such good eyesight. Worms are transparent, except for their eyes, which need to register light to function. Therefore, they cannot be inherently transparent. That means they come with evolutionary trade-offs. Since becoming visible must have come at a cost to the Vanadis, something about the evolutionary benefits of their eyes must outweigh the consequences.

It’s unclear exactly what the worms gain, especially since they are nocturnal animals that hide during the day, when their eyes typically work best.

“No one has ever seen the worm during the day, so we don’t know where it is hiding. Therefore, we cannot rule out that your eyes are also used during the day. What we do know is that their most important activities, such as finding food and mating, occur at night. So, that’s probably when your eyes are important,” says Garm.

Part of the explanation may be due to the fact that these worms see different wavelengths of light than humans see. Their vision is adapted to ultraviolet light, invisible to the human eye. According to Garm, this may indicate that the purpose of its eyes is to see bioluminescent signals in the otherwise pitch-black night sea.

“We theorize that the worms themselves are bioluminescent and communicate with each other through light. If you use normal blue or green light as bioluminescence, you also run the risk of attracting predators. But if, instead, the worm uses ultraviolet light, it will remain invisible to animals other than its own species. Therefore, our hypothesis is that they have evolved acute ultraviolet vision to have a secret language related to mating,” says Garm.

“It may also be that they are searching for ultraviolet bioluminescence prey. Anyway, this makes things really exciting, since ultraviolet bioluminescence has yet to be witnessed in any other animal. Therefore, we hope to be able to present this as the first example,” says the researcher.