Researchers have discovered that tiny crabs about a third of an
inch (one centimeter) long take care of a huge job. They
actually help keep coral reefs alive. And that's important,
because more than nine million species depend on coral reefs
around the world for food and shelter. These tiny crabs, called
trapeziid crabs, accomplish a lot despite their size. Particles
of dirt, or sediment, are bad for living coral. "If sediment
builds up on the coral, the weight of it can damage the coral,"
explains researcher Hannah L. Stewart of the University of
California Santa Barbara's Marine Science Institute. "Sediment
can also block the light healthy coral needs." Like many living
things, the crab and the coral have a symbiotic relationship;
that means they each help the other. The coral provides a home
for the crab, and the crab protects the coral. "An organism
doesn't just survive on its own," says Stewart. "There are a lot
of interactions that go into the success of every organism.
That's the web of life." Text by