Scientists have unveiled three previously unknown species of deep-sea sea spiders that use an unusual source of nutrition: methane. This research, published in the Proceedings of the National Academy of Sciences, sheds light on how these mysterious creatures thrive in the dark, methane-rich depths of the ocean.
A Unique Methane-fueled Diet
The deep ocean is known for its harsh conditions—extreme pressure, freezing temperatures, and the absence of sunlight. Yet, these newly discovered sea spiders have found a way to survive by grazing on bacteria that feed off methane. When organic matter sinks to the ocean floor and decays, it releases methane gas, which escapes through cracks in the sediment. Rather than floating away, the methane-fueled bacteria attach themselves to animals like the Sericosura spiders.
Shana Goffredi, a professor at Occidental College and the lead researcher of the study, explained, “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.”
This mutually beneficial relationship is the first of its kind observed in sea spiders. The bacteria convert methane and oxygen into sugars and fats, providing the spiders with a consistent source of nourishment. Unlike other sea spider species, which use large tubelike fangs to capture prey like jellyfish, the Sericosura spiders have no such appendages. Instead, they are more like farmers, “harvesting” the methane-fueled bacteria living on their bodies.
The Role Of Bacteria In The Ecosystem
This symbiotic relationship may also play an important role in regulating methane emissions in the ocean. Methane is a potent greenhouse gas, and while it can escape into the atmosphere, it is thought that the bacteria on these spiders could help prevent large amounts of methane from being released. As Goffredi noted, “While the deep sea feels really far away, all organisms are interconnected. Even though they’re small, these animals have a big impact in that environment.”
The study of such species could provide a better understanding of how deep-sea ecosystems interact with and regulate methane, which could have significant implications for climate science. The ability of these bacteria to thrive on methane may offer clues about how similar microbes could be utilized to mitigate methane emissions elsewhere on Earth.
Microbiomes And The Mystery Of Inheritance
One of the fascinating aspects of this discovery is how the Sericosura spiders pass their bacteria to their offspring. The female spiders lay hundreds of eggs, which are then carried by the males in saclike bundles. After hatching, the larvae are immediately introduced to the bacteria that reside on the father’s body. By analyzing the isotopes in the spiders’ tissues, the researchers confirmed that the bacteria were not merely hitching a ride but were being consumed by the spiders as part of their diet.
Nicole Dubilier, a marine biologist from the Max Planck Institute, pointed out the significance of this type of microbial transfer, stating, “This is really the beauty of the symbiosis between the two: The bacteria get that perfect Goldilocks zone with everything they need.” The bacteria’s survival, she explained, is tied to its relationship with the spiders. Even if 80% of the bacteria are consumed by the spiders, the remaining 20% continue to thrive and reproduce.
The Future of Marine Biology is Here
Goffredi believes that the deep ocean is far more diverse than previously thought, with many species inhabiting highly specialized environments. “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,” she explained.
With more studies to come, the Sericosura spiders may reveal even more secrets of the ocean’s depths and their role in maintaining the balance of the marine environment.