A team of researchers in Japan recently discovered a brand new species of starfish. The red, beige, and spongey Paragonaster hoeimaruae was found thanks to collaboration between scientists, fishers, and staff from aquariums and museums. It is described in a study published August 2 in the Journal of Natural History.
Also called sea stars, starfish are actually not really fish at all. They are echinoderms, a word that comes from the Ancient Greek for “hedgehog skin.” Starfish are more closely related to scum-sucking sea cucumbers and prickly sea urchins. Their signature arms and legs may also be one one giant head. While they might appear more docile and kind of helpless when sitting on a sandy beach, they are actually major predators. Some species can have up to 50 arms, grow up to three-feet-long, and live for decades. Many use their suction-cup adorned tube feet to latch onto the shells of bivalves to pry them apart and eat them.
[Related: These urchin-eating sea stars might be helping us reduce carbon levels.]
There are roughly 2,000 known species of starfish, and this new one was discovered in Japan by a team from the University of Tokyo, Enoshima Aquarium, Marine Science Museum, Fukushima Prefecture, and the Yamaguchi Prefectural Fisheries Research Center. It belongs to a family of starfish called Pseudarchasteridae. Previously, scientists only knew of four other species of Pseudarchasteridae, representing two genera in Japanese waters.
“We discovered the starfish–newly named Paragonaster hoeimaruae–off the coast of the Izu Peninsula in the Sagami Bay, south of Tokyo. We also found another in the Sea of Japan, northwest of Yamaguchi Prefecture in southwestern Japan,” Itaru Kobayashi, a study co-author and marine biologist from the University of Tokyo, said in a statement. “They were caught between 150 meters and 350 meters deep [492 and 1,148 feet-deep] have a well-proportioned body with five arms, and are a beautiful red on the surface and beige underneath.”
Between 2021 and 2023, the team gathered several varieties of starfish species around Japan. The starfish were collected from shrimp and crab cages used by fishers in northern Japan’s Hokkaido prefecture and Shizuoka prefectures in the central part of the country. A Yamaguchi prefectural fisheries research ship used beam trawl surveys as well. During this kind of marine survey, a large net is dragged across the ocean floor to collect specimens. The starfish is named hoei after the fishing vessel Hoei-maru, where the first specimen was collected.
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During their study, the team also recorded other starfish in locations where they had not previously been seen. The gunpowder sea star (Gephyreaster swifti), a surprisingly large starfish that’s almost one foot in diameter, was found off the north coast of Hokkaido. Gephyreaster swifti had previously only been seen across the Pacific Ocean off the coasts of the United States and Canada and north along to the islands in the Bering Sea.
“About 250 species of starfish live around Japan, and we were surprised that one so large as this had been overlooked. Our research highlights how the diversity of species in Japanese waters is still underestimated,” said Kobayashi. “These exciting discoveries show how important it is for fishers, aquariums, universities and other research institutions to work together to better understand our oceans and marine biodiversity.”