Spiky spiders

A Spotlight Specimens special for Oxford Festival of Nature

by Steven Williams, research student at Oxford Brookes University

I have been interested in Thorn Spiders since I was 12 years old. People are often afraid of spiders but the ones I study are not harmful to humans and I think they’re quite beautiful when you get up close and see them under a microscope.

They get the name ‘Thorn Spiders’ from the spines that protrude from their abdomen. These are assumed to be a defence mechanism but this has not been confirmed. The female Thorn Spiders are the ones with the larger spines – some reaching several centimetres in length; the males do not possess such striking features.

Steven Williams uses the Museum’s collections as part of his PhD research

My research revolves around how the different species of Thorn Spiders are related to each other and my aim is to create a kind of ‘family tree’ for the various species. I am also looking into the evolution of the spines and their habitats and distribution. They are commonly found across the Pan-Tropical region, with a few in the Americas and some in Australia. They are not found in Britain though unfortunately!

The handwriting on the specimen's label confirms that it was collected by Charles Darwin
The handwriting on the specimen’s label confirms that it was collected by Charles Darwin

Here are my three favourite specimens of these spiders from the Museum’s collection. The Australian Jewel Spider/Christmas Spider  (Austracantha minax), below, was collected by Charles Darwin on the Voyage of the Beagle when he stopped in Sydney, Australia.

I found this specimen when I was looking through the Museum’s dried spider collection; staff were not aware of its existence, and it is now stored with all the other Darwin specimens. We can confirm that it was collected by Darwin because the handwriting on the label is the same as in Darwin’s letters of correspondence.

An Australian Jewel Spider (Austracantha minax), collected by Charles Darwin during the Voyage of the Beagle

The metallic Thorn Spider (Gasteracantha scintillans), below, has a beautiful deep green metallic abdomen. It reminds me of a Ground Beetle’s wing cases and the rich metallic colour is something you wouldn’t normally see in spiders. They are only found in the Solomon Islands and this is a species I am working on currently for another area of my research, separate from my PhD.

Metallic Thorn Spider (Gasteracantha scintillans)
Gasteracantha scintillans has an unusual metallic green abdomen

And this last one, Gasteracantha thorelli, I think is one of the coolest species of thorn spiders. I just love the large spines on this spider! The way the final pair of spines curve round reminds me of a bull’s horns.

Gasteracantha thorelli has some impressive 'horns'
Gasteracantha thorelli has some impressive spines that look like a bull’s ‘horns’

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