The Sea Spider Farm: Harnessing Bacteria for Methane Consumption

Spider-like organisms dwelling near methane seepage seem to infiltrate the seabed, consuming microbes within their bodies that oxidize energy-dense gas. This discovery broadens the understanding of entities that rely on symbiotic associations with microorganisms in these alien settings.

Shana Goffredi from Occidental College, California, along with her team, has investigated marine arthropods named for their resemblance to ahinides, which thrive near three distinct methane seeps in the Pacific Ocean. They previously identified three new species from the sea spider genus Celico Sura, noted to be plentiful exclusively near these gas seepages.

In contrast, other sea spider species, which do not inhabit methane seep regions, primarily feed on various invertebrates. However, researchers have found that these newly identified sea spiders primarily acquire nutrition by ingesting a specific range of bacterial species residing in their bodies. These bacteria are capable of converting methane and methanol from the seepage into energy, something the sea spiders alone would not access.

Scientists observed that bacteria remained confined to the spiders’ exoskeletons, resembling “microbial fur coats,” and formed clusters that Goffredi describes as “volcanic-like.” The bacterial layer exhibited patterns resembling marks from a lawnmower, indicative of feeding by the spider’s robust “lips” and three tiny teeth.

To confirm that ocean spiders were actually consuming the bacteria, researchers employed radioactive labeling techniques to monitor the assimilation of methane carbon by laboratory sea spiders. “I observed methane being absorbed into the microorganisms on the spider’s surface, and subsequently traced carbon molecules migrating into the spider’s tissues,” Goffredi explains.

Researchers believe that ocean spiders do not consume all microorganisms growing on their exoskeletons. The species inhabiting the exoskeleton differ from those typically found in their surroundings, indicating a selection process is at play, Goffredi remarks. “The spiders are clearly cultivating and nurturing a unique microbial community.”

Sea spiders are not the first to cultivate microorganisms for chemical energy. “With every observation of these ecosystems near methane seeps, this phenomenon becomes increasingly evident,” notes Eric Cordes from Temple University, Pennsylvania. He previously collaborated with Goffredi on related studies, revealing a similar symbiosis in tube worms. The rich biodiversity near methane seepage is sustained not by solar energy but rather through methane and other chemicals. “That’s truly remarkable,” he remarks.

Cordes emphasizes that bacteria might also be transported along the surface of sea spiders. Unlike livestock on a farm, they gain superior protection and access to pastures. For instance, if methane seepage shifts to another area of the seabed, sea spiders could transfer bacteria to new locales. “Sea spiders maintain these organisms in an ideal habitat,” he adds.