Hermit Crab Using Anemone as Shell Among Creatures Found in Hydrothermal Seep at Jaco Scar

Posted on March 9, 2012

This hermit crab using an anemone as a shell - an example of anemone-hermit crab symbiosis - was one of the creatures found in a hydrothermal seep at Jaco Scar in depths off Costa Rica. A hydrothermal seep is a term for a recently discovered unusual ecosystem - the overlap between boiling hydrothermal vents and cold regions where methane rises from the ocean bottom. In addition to hermit crabs the hydrothermal seep is home to tubeworms, deep-sea fish, mussels, clam beds and high densities of crabs.

Boiling and frigid habitats overlap at Jaco Scar. Scientists have found environments known as hydrothermal vents, where hot water surges from the seafloor and life thrives without sunlight. They have also found cold, sunless habitats where methane rises from seeps on the ocean bottom. At Jaco Scar both strange extreme ecosystems exist side by side. The site lies at a tectonic plate margin off Costa Rica. There an underwater mountain, or seamount, is moving under the tectonic plate.

This large tubeworm bush was one of the creatures inhabiting the hydrothermal seep. There were over 14,000 tubeworms in the "bush."

Lisa Levin, author of the paper and a biological oceanographer at the Scripps Institution of Oceanography, says, "Plenty of surprises are left in the deep sea. There are new species, and almost certainly new ecosystems, hidden in the oceans. The site had been visited by other researchers using remotely-operated vehicles, but it wasn't until human eyes saw shimmering water flowing under a tubeworm 'bush' that we really understood how special Jaco Scar is."

David Garrison, director of the National Science Foundation's (NSF) Biological Oceanography Program, which funded the research, says, "The discovery shows that we still have much to learn about hydrothermal vents and methane seeps and about the vast depths of the oceans. We need to re-think the boundary, of where a vent begins or a seep ends."

Here is a photograph of Lamellibrachia barhami, a tubeworm that lives at hydrothermal vents and methane seeps.

The paper appears here in the March 7, 2012, issue of the journal Proceedings of the Royal Society B: Biological Sciences.

OCEANS