(Santa Barbara, Calif.) Tiny crabs that live in South Pacific coral help to prevent the coral from dying by providing regular cleaning "services" that may be critical to the life of coral reefs around the world, according to scientists from the University of California, Santa Barbara.

The story of the relationship between the crab and the coral is described in the November 2006 issue of the journal Coral Reefs and is now available on-line. The coral provides a home and protection for the crabs. The crabs provide "housekeeping" duties for the coral, routinely "sweeping" out sediment that falls onto the coral, according to the study.

Thus the relationship between the corals and the trapeziid crabs is mutually beneficial, or symbiotic. The little crabs, measuring only a centimeter wide, make their home in branching corals like Acropora or Pocillopora. The research was done on coral reefs near the shore of the French Polynesian island of Moorea, in the South Pacific.

"Although we don't know much about these crabs, we do know that they are 'picky,' and are always tasting and exploring," said Hannah L. Stewart, first author of the paper and a postdoctoral researcher at UCSB's Marine Science Institute (MSI). "They use their front appendages to manipulate and shovel out the sediment."

Stewart said that this family of crabs is common around the world. "This relationship probably occurs all over the Pacific and is likely more ubiquitous than we know," she said. "Crabs are in corals everywhere. There are major ecological implications to this research; species of crabs that associate with corals may be more important than we realized."

She explained that coral reefs are one of the most productive and diverse ecosystems in the world. They support more than nine million species and provide a livelihood for millions of people around the globe.

The accumulation of sediment on coral tissue is known to reduce metabolic and
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Contact: Gail Gallessich
gail.g@ia.ucsb.edu
805-893-7220
University of California - Santa Barbara
23-Oct-2006