Three new glow-in-the-dark marine worms have been discovered, named after creatures from Japanese folklore and a marine biologist

A research group from Nagoya University in central Japan has discovered three new species of bioluminescent polycirrus worms from different parts of Japan. Usually found in shallow waters, polycirrus are small worms that are known to bioluminescent. The researchers named one of their finds after a ghostly youkai, a creature in Japanese folklore. another after the yōkai lantern; and the other after the influential Japanese marine biologist. The researchers published their findings in the journal Royal Society for Open Science.

Scientists have studied only a small part of the more than 7,000 species of luminous organisms in the world. Research is still limited to certain species due to the presence of specimens that are difficult to classify into species. Without proper identification of species, comparisons of different results are of limited usefulness.

Naoto Jimi (him/him) and Special Assistant Professor Manabu Bessho-Uehara (him/him) at Nagoya University Graduate School led a research group including members from AIST, Olympus Corporation, and Japan Underwater Films Corporation, which organized Polycirrus according to their diversity. They discover the three new species, all of which emit blue-violet light.

When they discovered these new species, Jamie said, they were amazed and felt obligated to document and classify them. “Our previous research on the fluorescence of the genus Polycirrus has proven to be valuable material for bioluminescence studies,” he added. “However, we later discovered that what we thought was one species of Polycirrus was actually three different species.”

When researchers found the worms in Japan, they gave them Japanese names. They named two of the three species Polycirrus onibi and Polycirrus aoandon in reference to their bluish-purple sheen. In Japanese folklore, onibe (demon fire) describes a type of yōkai, in the form of a small, floating ball of light, believed to lead astray travelers in mountains and forests. Meanwhile, the aoandon (blue lantern) is a ghost-like yōkai that appears as a woman in a white kimono with sharp horns and teeth. The lanterns found in Japanese homes are haunting by turning their light an unnatural blue. The other worm, Polycirrus ikeguchii, was named in honor of Shinichiro Ikeguchi, the former director of the Notojima Aquarium.

“We used Japanese yōkai names, such as onibi and aoandon, for the new species because the hazy blue-violet bioluminescence emitted by Polycirrus species is strikingly similar to descriptions of these creatures found in folklore,” Jamie said. “Polycirrus ikeguchii, on the other hand, has been described from specimens collected in the Notojima region of Japan. Since Shinichi Ikeguchi was the former director of the Notojima Aquarium and helped find the worm, it seemed appropriate to name it after him.”

The researchers hope to use their findings to deepen their understanding of the molecular nature of bioluminescence, which could lead to the development of new technologies. “The discovery of all three new species are luminous allowed us to correlate taxonomic and ecological findings and establish research that others can easily apply to the study of luminous organisms,” Jamie said. “Understanding these luminescence mechanisms contributes to medical and life science research. Bioluminescence is a treasure trove of interesting and unusual chemistry. We intend to use our findings to deepen our understanding of the molecular nature of this phenomenon and to apply this knowledge in the development of new life science techniques.”