Three new species of rare glow-in-the-dark worms have been discovered in Japan that bear a “striking resemblance” to demons described in the country’s ancient legends.
The newly discovered species, Polycirrus onibi, Polycirrus aoandon and Polycirrus ikeguchii, belong to a family of animals known as ringworms, which are commonly found in shallow waters in Japan. These creatures emit a blue and purple glow, so that at night they look like the lighting of a foggy marsh.
Due to this characteristic of worms, researchers have suggested that they may have inspired ancient stories about Japanese demons, or youkai.

The connection between the naming of worms and ancient legends and demons
Also, the name of these worms is inspired by ancient Japanese legends. For example, an onbi (or demon fire) is a small, floating ball of light youkai that appears in remote mountains and forests to lead unsuspecting travelers astray. Aoandon is an embodiment of human horror, created by the fear of people who gather around blue lanterns to tell ghost stories. However, Ikeguchi makes no reference to ancient Japanese cultures. Instead, it was named after the former director of Notojima Aquarium, who helped discover the worm.
Polycirus worms are so named for the tentacles that protrude from their mouths that allow them to dig through river sediments to find food.
Now researchers are trying to figure out how these newly discovered worms can create their own light. Naoto Jimi, head of the research team and assistant professor of marine biology at Nagoya University, explains in his statement that bioluminescence (the production and emission of light by living organisms) is an interesting and unusual treasure of chemistry, and understanding its mechanisms is important for medical science research. And biology helps.