This Striking Species of Sea Slug With Six Donut-Shaped Structures on Its Back Leaves Researchers Stunned
Nature is filled with stunning beings whose visuals can take anyone's breath away. A photo of one such creature was captured by Bryan Blauvelt, who eventually became a runner-up at the 2025 Underwater Photographer of the Year competition, stated Nature. The magnificent slug's unique features reflect nature's brilliant artistry.
The creature that is the subject of the picture is Doto Greenamyeri. The most eye-catching feature of this being is the bouquet of donuts on its body, stated IFL Science. These donuts appear like six perfect ringlets on the slug's back. Due to these ringlets, the creature has been nicknamed the donut sea slug. These parts are called cerata, which are floppy projections visible mostly on aeolid nudibranchs. Though on D. Greenamyeri, the cerata are in a donut shape, in others, they take on different appearances. These parts are essentially branches of the digestive system.
In some species, these branches conclude with a cnidosac. This part acts like a storehouse of stinging nematocysts of their prey cnidarians. This adaptation is similar to what has been observed in many sea slugs that take away chloroplasts from the algae, which they usually ingest through kleptoplasty.
The nautical nudibranch was seen by Blauvelt when he was diving off Tulamben. Capturing the image was not easy at all, with the photographer using certain light tricks to get the final product. The photographer was grateful to his guide for all the aid throughout the trip. "I wanted to leave this inspirational place with a unique image of Doto Greenamyeri, one of the most striking subjects in Tulamben," said Blauvelt. "I created a dramatic glowing effect on the nudibranch with my strobe and snoot and completed the frame by backlighting the host hydroid with subtle blue light to balance the composition. Thank you to my incredible guide Rudolfi Sikome at Alam Batu for holding a torch in position for the backlighting effect on this image and for a productive and fun week of photography!"
The creature came into the limelight in 2015 when world-renowned expert, Dr. Tery Gosliner, identified it along with nine colorful new nudibranchs, stated the California Academy of Sciences. He discovered it during a student training expedition. The creature was spotted by an expert in southern Africa, an area boasting of diverse temperate marine environments, filled with a variety of slugs. Researchers claim that these slugs feed by sucking out the internal fluids of hydroid stems.
Most of his discoveries came from the tropical waters of the Philippines. "This remarkable stretch of coral rubble was carpeted in colorful nudibranchs—we discovered more than 40 new species," added Gosliner. "It was like an underwater Easter egg hunt. It was one of the most exciting scientific dives of my 50-year career."
"So many new findings indicate that nature holds many stunning secrets that people and experts need to work hard to bring to light. Biodiversity scientists estimate that we have discovered less than 10% of the species on our planet," added Dr. Meg Lowman, the Academy’s Chief of Science and Sustainability. "Academy scientists tirelessly explore the unexplored regions of Earth—not only to discover new species but also to uncover the importance of these species to the health of our natural systems. Our findings help inform conservation decisions meant to sustain the future of life for our children and grandchildren. Even in our own backyards."