California scientists stumble upon methane-eating sea spiders in deep ocean discovery

Los Angeles, California – In an unplanned twist to a scientific expedition, researchers exploring the ocean floor off the coasts of Southern California and Alaska have uncovered something astonishing: three new species of sea spiders that appear to consume methane. The discovery, made by a team led by Occidental College biologist Shana Goffredi, emerged not from a hunt for new creatures, but from an effort to study ecosystems surrounding methane seeps—geological formations where gas seeps up from beneath the seafloor and escapes into the ocean.

These “occasional streams of bubbles,” as described by the U.S. Geological Survey, are typically thought of as curious backdrops in deep-sea documentaries. But they’re also rich, dynamic ecosystems that remain largely mysterious. In 2021, while gathering specimens from these seeps and nearby hydrothermal vents, Goffredi’s team retrieved a number of organisms for laboratory analysis. Among them were several sea spiders—small, ghostly creatures already known to science.

But isotope analysis of their tissues revealed something highly unusual: the chemical signature of methane. That finding led to a closer examination, and eventually to the identification of three entirely new spider species—each adapted to survive and feed in these methane-rich habitats. The study, published this week in Proceedings of the National Academy of Sciences, notes that the spiders seem to consume methane indirectly, by relying on specialized bacteria that cling to their exoskeletons.

These methane-oxidizing bacteria are capable of converting the gas into a usable carbon source. According to researchers, the spiders scrape the bacterial coating off their bodies with their teeth—effectively harvesting their food from their own skin.

The implications of this are twofold. First, it marks a previously unknown pathway for methane to move through the ocean’s food web. And second, it underscores just how little is understood about the biodiversity and complexity of deep-sea environments. That’s especially relevant in an era of climate instability, when the role of the ocean in regulating Earth’s systems—oxygen production, carbon cycling, fisheries—has never been more crucial.

One of the new spider species was found at the Del Mar methane seep off the San Diego coast, and another near Palos Verdes. Each appears highly localized, with a range limited to specific seep sites, suggesting more discoveries may await in similarly unexplored regions.

That such revelations are still possible, even off Southern California’s densely populated coast, is thrilling—but it also puts into perspective other marine issues, like the ongoing sewage spills along nearby shorelines. In one part of the ocean, researchers are discovering unknown species at methane seeps; in another, beach closures are becoming routine due to human waste. It’s a striking reminder that while the deep sea holds secrets, the surface still needs serious attention.