“Lost” sea worm is rediscovered after 70 years in photos of seahorses

A kind of marine worm that scientists lost sight of for nearly 70 years has finally reappeared, thanks to close observation and a seahorse less than an inch long.

When researchers analyzed images of small seahorses taken by divers, they found evidence of hundreds of worms stealing the spotlight in the photos, living alongside the seahorses in coral colonies. between Japan and Australia .

The long-lost worm is the Haplosyllis anthogorgicolaa species of bristle worm, or polychaete. Generally, does not measure more than 6 millimeters and burrows within branching gorgonian corals at a density of up to 15 worms per cubic centimeter.

But the creature has not been directly observed in nature since 1956 when marine biologist Huzio Utinomo of Kyoto University first identified it, according to a new study published by scientists in the journal Proceedings of the Royal Society B: Biological Sciences.

Finding these worms is extremely challenging because your small size and almost total transparency make them virtually impossible to see underwater, according to the study’s lead author, Chloé Fourreau, a doctoral candidate at the Laboratory of Invertebrate Systematics and Molecular Ecology (MISE) at the University of the Ryukyus in Okinawa, Japan.

“I love how this article uses public footage to learn more about where and how these animals occur, and what they are doing,” he says Karen Osbornresearcher and curator in the department of invertebrate zoology at the Smithsonian National Museum of Natural History, in Washington, United States.

With about 10 thousand species identified of bristle worms and perhaps twice as many yet to be discovered, there are many open questions about the biology of polychaetes, interactions with other species, “and the impacts they have on the areas they inhabit,” adds Osborn, who was not involved in the study, in an email. “This article beautifully shows how they are right under our noses but practically unnoticed.”

“She noticed some worms.”

Study co-author Ai Takahata, a graduate student at MISE and Forreau’s lab partner, was researching the camouflage of pygmy seahorses (Hippocampus bargibanti) when he unexpectedly found several worms H. anthogorgicola in coral samples collected in waters near Japan.

“When she cut a branch of coral, she noticed some worms coming out of it,” Forreau said. “She gave them to me because she knew I was interested in polychaetes, but before I looked at the worms, I didn’t even know about this species.”

Forreau told CNN who suspected that pygmy seahorses’ gorgonian coral colonies might yield more worms. In 2023, during unrelated research in South Sukumo Bay in Kochi, Japan, she asked the boat captain to make a detour to collect coral samples, and found bristle worms. H. anthogorgicola inside them.

But when he went to organize his underwater photos of seahorses and corals, Forreau made another unexpected discovery: worm holes in corals were visible in the images. Perhaps, the researcher thought, this could also be the case in other photos of pygmy seahorses.

Scientists turned to iNaturalist, a website where people share nature images and information about biodiversity, to find photos of pygmy seahorses (and possibly their wormy neighbors, too).

Because pygmy seahorses are very small – with about 2.5 centimeters long – divers tend to photograph them in extreme close-ups, which include detailed views of nearby corals.

On iNaturalist, 489 photos of the seahorses also included evidence of worms according to the researchers. Images of pygmy seahorses taken by divers were full of worms stealing the show. Limbs, heads and tails of the worms appeared emerging from the coral burrows by the hundreds.

Scientists have even counted seven examples of worms crawling on the bodies of seahorses. Tunnels of worms snaked through the coral branches and into the polyps, and approximately 84% of the corals photographed had worm infestations according to the researchers’ estimate.

Greater distribution of bristle worms

Before this study, very little was known about the distribution and habits of H. anthogorgicola. Reconstructing the lifestyles of hard-to-find animals is especially challenging when published research on them is almost nonexistent, according to Forreau.

“But our article shows that we can reuse the wealth of information available about better-known species to learn about less studied ones, such as worms,” added the scientist, via email.

The GPS coordinates in the iNaturalist photos expand the worms’ potential distribution greatly. further south than previously thought covering Australia, East Timor, Indonesia, Japan, Malaysia, New Caledonia, Papua New Guinea, the Philippines and Taiwan, according to the study.

Utinomo’s 1956 paper linked worms to just one species of coral — Anthogorgia bocki — but analysis of the photos suggests that these worms inhabit other corals of the genus . The images also provided the first evidence of worms directly interacting with seahorses .

Polychaetes live in diverse habitats “including polar ice, methane seeps and deep-sea hydrothermal vents, the spaces between corals and the vast open ocean,” Osborn describes. “They are critical to food webs and build habitat for other animals.”

iNaturalist photos answered some old questions about the lifestyle and habits of H. anthogorgicolaadds Forreau. “They confirm that worms are highly dependent on their burrows – most of the time is spent inside them.” In many of the images, the only visible part of a worm was its antennae and other dangling appendages sticking out of the tunnel.

“This position suggests that worms spend a lot of time sensing their surroundings perhaps waiting for something to eat in the water, or to detect the movement of the coral polyp to steal its food”, observes the researcher.

However, many of the burrows were not close to the polyps, suggesting that worms could be coral cleaners instead of food thieves. “There is still a lot to be learned about the relationship between worms and the corals where they live,” concludes Forreau.

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This content was originally published in “Lost” sea worm is rediscovered after 70 years in photos of seahorses on the CNN Brasil website.

Source: CNN Brasil