Newly Discovered Sea Spiders Have Unique Eating Habits

Scientists have discovered three new species of sea spider off the US West Coast that appear to survive by teaming up with bacteria to feed on methane seeping from the ocean floor. The spiders, each about the size of a grain of rice, were found in deep-sea habitats thousands of feet down, far beyond the reach of sunlight, according to research published in the Proceedings of the National Academy of Sciences. The relationship between the spiders and the bacteria is a curious one: The bacteria set up shop on the spiders' exoskeletons, converting methane and oxygen into sugars and fats that the spiders then consume.

"Just like you would eat eggs for breakfast, the sea spider grazes the surface of its body, and it munches all those bacteria for nutrition," Shana Goffredi, the study's lead author, tells CNN. Marine biologists say the symbiosis is a good deal for the bacteria, even if most of them get eaten. Unlike other sea spiders that hunt prey, these newly described Sericosura species don't have the usual appendages for capturing food, meaning they likely "farm" their own bacteria. This adaptation may help keep methane—a potent greenhouse gas—from reaching the atmosphere. Goffredi says even tiny animals like these play a significant role in deep-sea ecosystems and may eventually inspire methods for reducing water contamination elsewhere.

Goffredi says the three species were found in separate areas off the coasts of California and Alaska, suggesting there could be many other similar, highly localized, species. "People tend to think of the deep sea as a kind of homogeneous ecosystem, but that's actually untrue. There's a lot of biodiversity by region and animals are very localized to specific habitats on the seafloor," Goffredi says. "You have to be very careful if you decide to use the seafloor for mining, for example. We don't want to cause any kind of irreparable harm to very specific habitats that aren't found anywhere else." (This content was created with the help of AI. Read our AI policy.)