Sea spiders living near methane seeps on the seafloor have been discovered to cultivate and consume microbial species on their bodies that feed on the energy-rich gas. This symbiotic relationship expands our understanding of the diverse organisms that thrive in these unique environments.
Researchers led by Shana Goffredi at Occidental College in California studied sea spiders near three different methane seeps in the Pacific Ocean and identified three previously unknown species from the genus Sericosura. These sea spiders rely on a unique set of bacterial species living on their bodies for nutrition, as opposed to other invertebrates like their non-seep dwelling counterparts.
The bacteria found on the sea spiders’ exoskeletons form a “microbial fur coat” in volcano-like clusters. These bacteria metabolize methane and methanol from the seeps, converting it into energy that sustains the sea spiders. The researchers observed markings on the bacterial growth that suggest the spiders may actively consume these microbes using their specialized mouthparts.
To confirm that the sea spiders are indeed consuming the bacteria, the team used a radioactive labelling technique to track the carbon from methane as it was incorporated into the spiders’ tissues. This evidence supports the idea that the sea spiders actively cultivate and consume a specific microbial community on their bodies.
This farming behavior is not unique to sea spiders, as other organisms near methane seeps have been found to engage in similar symbiotic relationships with microbes. Erik Cordes from Temple University, who collaborated with Goffredi on a previous project involving tube worms, notes that these symbiotic partnerships play a crucial role in the ecosystem’s energy dynamics. The abundance of life near methane seeps is sustained by chemical energy rather than solar energy, highlighting the unique adaptations of organisms in these environments.
In addition to providing nutrition for the sea spiders, the bacteria benefit from this relationship by gaining protection and access to new habitats. Similar to cattle on a ranch, the bacteria hitch a ride on the sea spiders to move to different methane seeps if the environment changes. This mutually beneficial arrangement showcases the intricate balance of nature in these deep-sea ecosystems.
Overall, the discovery of sea spiders cultivating microbial communities on their bodies sheds light on the complexity of symbiotic relationships in extreme environments. By studying these interactions, scientists can gain valuable insights into the adaptations that allow organisms to thrive in challenging conditions.
