A large house spider might seem like a thoughtless killing machine, but a team of biologists claim arachnids have distinct personalities.
While some individuals might be aggressive, other arachnids could be naturally ‘timid’ and docile’,the researchers said.
They studied social grass spiders and found that a spider’s personality not only determines the creature’s survival, but contributes to the success of failure of its society.
Researchers from the University of Pittsburgh, led by Jonathan Pruitt, found the spiders could be timid or aggressive and prone to sexual cannibalism.
While most spiders live solitary lives and territorial of their webs, a handful of species live in social groups where females share the upkeep of the web as well as jobs like raising their young and defending their home from intruders.
The study, which took six years and was published in journal Proceedings of the Royal Society B, in July, examined sociable grass spiders.
The researchers categorised the spiders into two groups — aggressive or docile — to investigate how the mixture of personalities serves the community’s well-being.
They established three different spider colonies in Tennessee, beginning with a pair of docile spiders, a pair of aggressive spiders and a mixed pair.
Leaving each colonies to go forth and multiplying the wild, the scientists checked on the creatures’ progress every summer for six years.
While the docile colony seemed to be thriving at first — reproducing faster than the others and spreading colonies nearby — their webs were invaded by more aggressive species that stole their food and eggs as well as eating the passive hosts.
At the end of the six year term, the colonies descended from the docile pair were extinct, while the colonies started by aggressive pairs and a mixture of the two personalities survived, even if their colonies got off to a slower start as they reproduced more slowly.
The biologists found that the animals’ personalities didn’t matter if there was no common enemy as when there were no invading species, all the colonies thrived.
Dr Pruitt said the aggressive spiders acted like the colony’s immune system.
He told the Orlando Sentinel: ‘They keep this social disease, these parasites, at a low abundance.’
They also found that while bold spiders were often aggressive there was no link to their body size and larger spiders could be docile.
‘Hence, we show that personalities shape task differentiation in a social spider independent of age,’ the write in the study.
The researchers have now turned their attention to other species and are looking at sexual cannibalism in grass spiders as well as social spiders in India and Africa.
They are also examining the personalities of tiny slave-making ants that enslave other ant species inside acorns and force them to find their food and raise their young.
Dr Pruitt said: ‘Sometimes they’ll have a revolt and kill the slavemakers, but it’s pretty infrequent. I bet you it has something to do with their personality types.’
