May 30, 2006
Observatory
Lobsters Quarantining Lobsters
By HENRY FOUNTAIN

Give a cold a cold shoulder. It may be going against humans' social nature, but steering clear of someone with the sniffles is a good way to avoid coming down with them.

From an evolutionary perspective, such behavior makes a lot of sense. Avoiding diseased members of the species is one way for the fittest to survive.

"It seems like a logical thing for a species to evolve, but it's not common," said Mark J. Butler, a professor at Old Dominion University.

Now Dr. Butler, Donald C. Behringer of Old Dominion and Jeffrey D. Shields of the Virginia Institute of Marine Science have discovered similar behavior among another social animal, the Caribbean spiny lobster. They report in the current issue of Nature that healthy lobsters stay away from others that are sick with a deadly virus.

Dr. Behringer first noticed diseased lobsters several years ago during research in the Florida Keys. They were discolored and lethargic, and their blood, normally colorless, was milky white. Dr. Shields identified a virus, PaV1, causing the disease.

Unlike clawed lobsters, spiny lobsters are social, hanging out in groups under large sponges or in rock crevices during the day before feeding at night. "But we found these sick animals all by themselves," Dr. Butler said.

Experiments showed why. When healthy lobsters were given a choice in a lab setting between an empty den and one with a sick lobster, they chose the empty den. Further studies showed that healthy lobsters avoided sick ones weeks before there were visible symptoms and before the sick lobsters became infectious. That's a good thing, Dr. Butler said, because if lobsters catch the virus "they're pretty much goners." He said the healthy lobsters probably detected chemical cues released by the sick ones.

The finding has implications for conservation, as the lobster habitat is being diminished by humans. "If you're wiping out the housing market, so to speak, now you have animals constrained and forced together," Dr. Butler said. Healthy lobsters may have no choice but to mingle with sick ones, raising the risk that the disease will be transmitted.

Dr. Butler said it was likely that other species adopted similar shunning behavior. "It's a very effective way for animals in the wild to keep diseases from spreading," he said. "It's probably something we just haven't recognized in other species."