Sea worm’s reproductive bits grow their own eyes before mating

Branching Marine Worms: A Unique Reproductive Strategy

Even among the numerous gnarly animals swimming, crawling, and “flying” through the world’s oceans, the branching marine worm (Ramisyllis kingghidorahi) has a very interesting reproductive style.

Named after Godzilla’s three-headed nemesis, King Ghidorah, the worm lives inside sea sponges in the Sea of Japan and reproduces by growing multiple body branches within the host sponge. Each of these tails can then produce separate living reproductive units called stolons—which can grow eyes. The stolons themselves do not live too long and break off from the branches to swim away to mate.

How this spindly animal can coordinate sexual reproduction with so many stolons across so many branches has puzzled scientists since its discovery in 2021 and 2022. We may have an answer though. The genes that control eye formation might be particularly active in Ramisyllis, which helps make more stolons, according to a study recently published in the journal BMC Genomics.

In the new study, the team analyzed the gene expression across the different body regions on male, female, and juvenile specimens. This created a complete genetic activity map—or transcriptome.

With this genetic activity map in tow, the team saw some clear patterns. The differences in gene activity were more pronounced between the different body regions in the same worm than they were between the sexes. When comparing males with females, the stolons had the most distinctive genetic signatures. This likely reflects the stolons’ specialized role in gamete production and metamorphosis.

“We were surprised to find that the head of the worm, which was previously thought to house a sex-specific control system, didn’t show the dramatic differences we expected between males and females,” Guillermo Ponz-Segrelles, a study co-author and neuroscientist with the Autonomous University of Madrid, said in a statement. “Instead, the stolons emerged as the true hotspots of gene activity during sexual development.”

When looking into what’s behind the stolon eyes, the team found that there is upregulation of the genes related to eye development. Upregulation is the process by which genes are activated and produce more of the proteins corresponding with a certain gene’s function. This genetic upregulation could help Ramisyllis develop more of the eyes on their many stolons.

There could also be partial genome duplication in Ramisyllis, which may help explain why this worm has such a complex anatomy and reproductive system. Either way, it is equipped with a very unique genetic toolkit.

“This worm and its surreal, tree-like body made headlines around the world in 2021 and 2022, yet it continues to amaze us,” added Thilo Schulze, a study co-author and PhD candidate at Göttingen University in The Netherlands. “It challenges our understanding of how animal bodies can be organized, and how such strange forms of reproduction are orchestrated at the molecular level.”

Since numerous parts of branching worms’ reproductive biology remain a mystery, the team hopes the genetic tree from this study will help show how life evolves in some of the ocean’s hidden spots. Laura has always had a keen interest in a variety of scientific subjects, but she is particularly fascinated by all things aquatic, paleontology, nanotechnology, and exploring how science influences daily life. From the depths of the ocean to the mysteries of ancient fossils, Laura is constantly seeking to expand her knowledge and understanding of the world around her.

Her love for all things aquatic stems from a childhood spent by the sea, where she would spend hours exploring tide pools and watching the ebb and flow of the tides. This early exposure to marine life sparked a lifelong passion for the ocean and its inhabitants, driving her to learn more about marine biology, oceanography, and conservation efforts to protect our oceans for future generations.

Paleontology is another area of interest for Laura, as she is fascinated by the study of ancient life forms and the clues they provide about the evolution of our planet. From digging up dinosaur bones to studying prehistoric fossils, she is always eager to uncover the secrets of the past and piece together the story of how life on Earth has evolved over millions of years.

Nanotechnology is a cutting-edge field that has captured Laura’s imagination with its potential to revolutionize everything from medicine to electronics. By exploring the world of nanoscale materials and devices, she is constantly amazed by the ways in which science is pushing the boundaries of what is possible and opening up new opportunities for innovation and discovery.

But perhaps most intriguing to Laura is the way in which science influences daily life, from the technology we use to the food we eat. By delving into the ways in which scientific advancements impact our day-to-day existence, she is able to gain a deeper appreciation for the interconnectedness of the natural world and the human-made innovations that shape our modern society.

In her quest for knowledge and understanding, Laura is always seeking out new opportunities to learn and grow in her chosen fields of interest. Whether she is diving into the depths of the ocean, uncovering the secrets of the past, exploring the world of nanotechnology, or examining the ways in which science shapes our daily lives, she is constantly inspired by the wonders of the natural world and the incredible advancements that science has to offer.