During a dive in a manned submersible off the coast of Panama, the team came across the large aggregation of swarming red crabs at depths of 355 to 385 metres in an area of "hypoxic" (low oxygen) water.
Biologist and chief scientist on the cruise Jesús Pineda said: "No one had ever found this species that far south. To find a species at the extreme of their range and to be so abundant is very unusual.
"These crabs have been detected before in similar low oxygen conditions. It could be that these low-oxygen waters provide a refuge for this species from predators."
The researchers plan to return to the Hannibal Seamount to further study why seamounts support such high levels of biodiversity. In addition, the deep-water areas of Hannibal Seamount, which lack dissolved oxygen and are acidic, give scientists an opportunity to investigate how communities might look in the future as the ocean responds to climate change.
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