Deep Ocean Discovery: A New Species With 5 Arms and Spear-Like Teeth

The Marianna Trench is the deepest area of the ocean, and therefore one of the most mysterious underwater regions in the world. The Mariana Trench Environment and Ecology Research expedition (MEER) has recently uncovered details of over 7,000 microbial species, roughly 90% of which were previously unknown species. Most notably, genome analysis revealed two incredible survival strategies. The first was an adaptation to a highly pressurized environment at 6,000 meters deep, while the other relates to survival amid nutrient limitations. Details of the expedition are published in the scientific journal Cell.

While discovering new microbial organisms is interesting, finding larger animals is even more thrilling. Over 25,000 feet below the surface in the Philippine Sea, scientists discovered a brand-new species of brittle sea star. While the new species was first sighted in 2021, the Chinese research group published their findings on September 26, 2023. Named Ophiuroglypha fendouzhe after the submarine used to locate it, the new brittle sea star is the first of its kind found at these depths. What sets it apart from similar species are its long, slim arms covered with separated arm plates shaped like diamonds. Not only that, but their scales that overlap and their tooth shape resembles spearheads are also unique. These brittle stars are very small. Their center only measures 0.4 inches in diameter and each of their five legs reaches only about 2.2 inches long. Five specimens were transported to the Institute of Deep-Sea Science and Engineering at the Chinese Academy of Sciences in Sanya, China, for further study. Additional research is still being conducted. Now that we’ve learned a bit about the new brittle star species let’s learn more about these neat creatures as a whole!

This post was updated on July 23, 2025 to include information on the MEER expedition.

How Many Species of Brittle Stars Are There?

Aside from the new brittle star species, we know of about 2,100 different kinds. Brittle stars make their homes in oceans worldwide, including the Arctic Ocean. They vary in preferred habitats, foods, and depths. Marine biologists study these creatures regularly as the health of their populations gives us clues to the health of the ocean. These creatures clean up waste material from the sea floor. Japanese scientists have discovered a new way to study brittle stars! They found that by sampling the seawater and looking for environmental DNA (eDNA) left behind by the brittle stars, they could determine the size of the population in the surrounding water. They were also able to figure out which species lived in the area. Isn’t that neat?

What’s the Difference Between Brittle Stars and Starfish?

The new brittle star species, along with all its cousins, belong to the Ophiuridae family. Meanwhile, starfish belong to Asteroidea. All 7,000+ species together are echinoderms. Brittle stars only have five legs that they use to move around. Starfish, like the Antarctic sun starfish (Labidiaster annulatus), can have as many as 50 legs. However, they use tiny feet (podia) to help move them along in their environment. Starfish have thick legs that taper to a point and are connected to their body. On the other hand, brittle stars have long, thin legs connected to a central disc where all their vital organs are located. Starfish’s vital organs are located in their legs. Starfish commonly live up to 35 years though brittle stars live only five years. Lastly, starfish are mostly meat eaters (carnivores), while brittle stars eat both plant and animal matter (omnivores). Some brittle stars feed strictly on detritus (or decaying organic matter).

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