The Australian trapdoor spider that prefers living a sedentary life has likely made a sea journey of thousands of miles from South Africa to arrive in Australia, suggests a study carried out by researchers from the Australia’s University Of Adelaide.

Australian trapdoor spider found off the south Australian coast

The Australian trapdoor spider, scientifically known as Moggridgea rainbow, is found off the south Australian coast. They are little creatures that can fit on a fingernail. According to scientists, these spiders rarely move more than a few feet from where they are originally hatched.

They make burrows within the bark of trees to hide or rest in and then seal their burrows by creating a hatch for them. They usually line their burrows with silk, and then start enjoying a comfortable environment within it. They come out of their trapdoors mostly at night to catch prey. After killing the prey, they return to their burrow to consume it.

Australian trapdoor are related to spiders found only in South Africa

In 2013, Sophie Harrison, a researcher from Australia’s University of Adelaide, was studying how armored trapdoor spiders diversified into different species over time. She got some specimens from a wildlife photographer Nick Birks and analyzed the genetic sequences of these spiders.

Surprisingly, she found that Australian trapdoor spider belongs to a genus of trapdoor spiders found only in South Africa.

DNA study also suggested that Australian trapdoor split off from its closest relatives about 2 to 16 million years ago. This finding was contrary to the conventional wisdom that such a split would have occurred about 95 million years ago when African continent was separated from Gondwana.

Harrison and her teammates used the molecular clock dating technique to establish the timing of separation.

The new finding also ruled out the theory that these spiders reached Australia with humans. Studies have revealed that the first humans arrived in Australia continent about 65,000 years ago. The finding meant that spiders didn’t hitch a ride with humans, and a long-distance sea journey was the most plausible option for their method of arrival into Australia.

Furthermore, these spiders have relatively slow metabolism, meaning that it was possible for them to survive the long ocean journey.

Researchers suggest that the migration of these spiders might have started following a landslide or uprooting of a tree that would have knocked burrows of trapdoor spiders into the ocean. These spiders, in their sealed confines, were then carried by the ocean currents to reach Australia eventually.

The detailed findings of the study have been published in the journal PLOS ONE.
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