Piled three feet thick, spider crabs are swarming off the coast of Australia. Stacked 10 crabs high, the swarm covers the size of a football field. Scientists estimate that some 500,000 crabs have come closer to shore than ever before. This may be the largest gathering of spider crabs ever. The swarm, which began in early June, has presented a rare opportunity for marine scientists to study spider crabs. The gigantic clustering is already dispersing, which is good news for the local sea life. Many of the regular residents of the sea have been scared away from the area. Some suggest it is pre-mating behavior, while others suggest that the crabs come into shallow water to get out of cold deep water at this time of year. Crabs in a swarm are also protected from predatory fish, he said. The Museum Victoria is filming the swarm for an exhibition on the marine environment. Spider crabs grow to about the size of an adult human hand. A spider crab can grow up to nine inches in size with 18-inch legs. The orange colored spider crabs are usually loners. They are native to the seawaters in southern Australia. They eat decaying fish, seaweed and snails, but can also eat sea stars.
Source: Swarming