Hermits Show New Social Behaviors
By seeding vacant shells into field populations and staying up all night to see what happened, the scientists discovered some previously unknown hermit crab behaviors. When a hermit crab discovers an empty but oversized shell, it waits nearby rather than simply walking away. Once a small group gathers, crabs begin piggybacking by holding onto the shell of a larger crab and riding along. Such waiting and piggybacking behaviors seem to increase the chances that a synchronous vacancy chain will happen. "They spend hours queuing up, and then the chain fires off in seconds, just like a line of dominoes," says Rotjan. Computer models populated with virtual hermit crabs and shells confirmed that synchronous vacancy chains depend not only on crab density, but also on how long crabs are programmed to wait near an unsuitable shell.
According to Rotjan, the same kind of synchronous vacancy chain can occur with any animal that relies on discrete and reusable resources, such as anemone-dwelling fish and hole-nesting woodpeckers. Studying vacancy chains in hermit crabs might even lend new perspective on human behaviors, since people regularly participate in synchronous vacancy chains. For example, every September 1, neighborhood streets in Boston, Mass., are clogged with rental trucks and moving vans. This signals that the city's many
|Contact: Kim Thurler|