Interesting behavious among Australian arthropods
Posted: Wed Mar 19, 2008 11:16 am
Battles to the death are taking place across Australia as huntsman spiders fight it out for the family home.
Linda Rayor, a visiting fellow at the Australian National University in Canberra, uncovered the gruesome family feuds while studying the tree-dwelling Delena cancerides spiders.
Dr Rayor, from Cornell University's Department of Entomology, says her study of of the species has shown it is the only one of the 1,039 known huntsman species that lives a social life with family members.
Among the world's 40,000 known spider species only 1 per cent are social, and this species is one of only two that do not spin webs.
Dr Rayor believes the communal lifestyle has been thrust upon the spider by a lack of suitable accommodation in the wild.
And in travels around remote Australia looking for the spider, she found the arachnid is in the midst of a housing crisis.
Scarce habitat
With an adult female weighing up to 4.5 grams and with a leg spread that can exceed 14 centimetres, Dr Rayor says the spider is limited in finding large enough spaces to live.
"They are trying to fit themselves into retreats under the bark of wattle trees and it turns out there are remarkably few of these habitats around," Dr Rayor said.
"You might find two trees by the side of the road that house Delena, and the next trees are a 100 metres or more away.
"The colony is producing all these offspring that want to start their own colony but they have nowhere to go."
Dr Rayor said the nest can be home to more than 100 spiders with up to 30 sub-adults.
"There is nothing like it in the spider world," she said.
In some areas, her team found 100 per cent occupancy of possible habitats with the most "spectacular locations" for the spider about 62 per cent full.
Family ties
But the family ties only bind as long as the mother of the spider nest is alive.
Dr Rayor said the mother defends the nest against predators and seals it off from attack, brings prey home to feed the family, and generally keeps the peace.
However on her death, familial loyalty is forgotten, Dr Rayor said.
Because of the lack of habitats there is intense competition between sexually mature sisters to inherit the family site from the mother, she said.
"I've seen sisters in fights to the death," she said.
So....how many people did I freak out with that picture?
