June 18, 2014
Lover Or Fighter? Spider’s Job Type Depends On Personality
Brett Smith for redOrbit.com - Your Universe Online
We all know that our personality type can affect how well we perform our job, but does the same principle apply to other species?
According to a new study in Proceedings of the National Academy of Sciences, it does apply to spiders – as a team of researchers has found aggressive spiders are better at killing prey and defending the colony, while docile spiders excel at caring for the baby spiders. The study focused on Anelosimus studiosus spiders, which can be found spinning their tangled communal webs in ecosystems across both North and South America.
"We can see very strongly that personality matters," study author Colin Wright, of the University of Pittsburgh, told National Geographic's Marcus Woo. "It's probably the best example of how personality can shape or organize labor within a colony."
Female Anelosimus spiders are considered either aggressive or docile and to determine which type of personality a spider in their study had – the scientists put two spiders in the center of a box. If, after a full day, both the spiders shifted close together, they were considered docile and cooperative. However, if they traveled to opposite corners, at least one of the spiders was considered aggressive, since an aggressive spider demands personal space. Aggressive spiders were then coupled with a known docile spider to ascertain if they were in fact aggressive.
Next, the spiders were placed into a more natural, social setting. The scientists kept an eye on which job each personality type selected. The aggressive spiders were found spending most of their time protecting the colony, constructing webs, and catching prey. At the same time, a large number of docile spiders spent most of their time taking care of the offspring.
The scientists also discovered that character lined up with job performance. The aggressive arachnids were better at warding off an intruder, mending a broken web, and pouncing on a cricket for food. However they were poor at looking after their young, leading to lower survival rates. They also unintentionally slaughtered the offspring considerably more often than docile spiders did.
"One of the more surprising things was to know (what) good parents the docile individuals were," Wright says.
Previous studies had shown that a mix of aggressive and docile spiders produced the most successful colonies, but the role of docile spiders hadn’t been clearly defined.
"For a long time we weren't quite sure what the purpose of the docile spider was,” Wright said.
The study authors concluded that if personality can influence job selection and performance in spiders, then it stands to reason that the same could apply to any social creature, including us.
“Division of labor is often assumed to be a feature only of highly evolved societies, such as the ants and honeybees—and humans,” said Jennifer Fewell, a behavioral ecologist at Arizona State University who was not part of the study team. “However, it is a fundamental organizing principle across social species."
"The more animals you study, the more you realize you're an animal yourself,” Wright noted.