CANBERRA, Aug. 3 (Xinhua) -- The iconic Australian trapdoor spider did not migrate to the "Great Southern Land" through human intervention, local researchers said on Thursday; rather, it may have been a castaway which drifted across oceans.
According to PhD candidate Sophie Harrison from the University of Adelaide, the Australian trapdoor spider, or Moggridgea rainbowi, came from Africa between 2 million and 16 million years ago.
That means the species' colonization on Kangaroo Island in South Australia predates human settlement in Australia, but also came well after Australia and Africa were linked as part of Gondwanaland.
Harrison's research was published in the PLOS One journal on Thursday, and concluded that the spider made its way to Australia "via long-distance trans-Indian Ocean dispersal, representing the first such documented case in a mygalomorph spider."
"(The Australian trapdoor spider) is really prone to being short-range endemic species and having these really restricted distributions, and then suddenly you get this one that's come across the ocean, it's really not what you'd expect," Harrison said.
"Usually, (the connection between the Australian and African trapdoor spiders is) because there was a widespread common ancestor and then when the continents drifted apart the distributions remained."
She said while it's hard to imagine a spider surviving for a long time on ocean junk, the trapdoor spider is known to have "awful dispersal abilities," meaning they would have been very comfortable on a small "raft" drifting across the seas.
"Even though they've got these awful dispersal abilities, they're nice and secure in a raft or a chunk of land," she said.
"(If) they've got a really secure burrow and a really nice fitting trapdoor lid -- and they've got pretty low metabolic requirements -- (they) don't require much resources," Harrison said.
