A new genus of deep-sea polychaete worms has been described after a study of the seafloor off Christmas Island and Cocos Islands in the Indian Ocean. Terebellosuctoria is distinguished by unusual suction-cup-like structures on its underside.
The new genus belongs to the Terebellidae family, whose members are known as “spaghetti worms” because of their long tentacles. They build tube-like shelters in soft sediments and use their tentacles to collect fine food particles from the surface of the seafloor. The study was published in the journal Records of the Australian Museum on 8 July 2026.
Expeditions collect over 850 worms
The specimens were collected during expeditions in 2021 and 2022 with the research vessel Investigator. The scientists explored seamounts off Christmas Island and the Cocos Islands, collecting more than 850 marine worms.
The paper describes seven new species from three families, two of which are included in the new genus Terebellosuctoria. One of the species was found at a depth of over 670 metres off the Cocos Islands. When the samples were taken by bottom trawling, the scientists' attention was drawn to numerous branching brown tentacles.
Bright orange worms emerged from the tubes, some of which reached 75 millimeters in length. One of the species has been named Terebellosuctoria jimii in honor of Naoto Jimii, who had previously described similar suction-cup-like structures in another marine worm.
Suction cups may help on rocky slopes
After analyzing the body shape, DNA and scanning electron microscope images, the researchers concluded that this is not only a new species, but a previously unknown genus.
According to the scientists, these structures may be an adaptation to an environment with little soft sediment. The slopes of seamounts make it difficult for worms to build their usual tube-like shelters, so the sucker-like growths probably help them stay on the surface.
“Marine worms are among the most abundant and diverse animals on the seafloor, but they remain overlooked and underappreciated. Only a small fraction of them have been formally named and described,“ said Pat Hutchings, a senior research fellow at the Australian Museum.
The researchers note that identifying the organisms they collect can take years. Expeditions often collect hundreds or thousands of specimens, which are then examined using morphological and genetic methods.
Sources: unian.net, independent.co.uk