How It Works

World’s most venomous spiders are long lost cousins

You would not like to find these cousins hanging out in your home. These two groups of dangerous spiders carrying highly venomous toxins found are both found in Australia, and have been considered only distantly related until recently.

San Diego State University biologist Marshal Hedin has led and published results of a project in the last months issue of Nature Scientific Reports. The research has discovered the families Atracinae and Actinopodidae are in fact close evolutionary cousins.

The first spiders appeared on Earth approximately 380 million years ago during the Devonian Period, meaning they were scuttling around with their creepy legs more than 150 million years before the dinosaurs. Atracinae and Actinopodidae were thought to have appeared from a common ancestor around 200 million years, but bites from either family can be treated with the same antivenom – leading scientists to suspect they are more closely related that they originally thought.

Hedin’s team, with help from colleagues in New Zealand and Argentina, collected new spider specimens from the Australian outback, and old specimens from personal collections and museums to create a selection of samples representing various branches of spiders both closely and distantly related. The researchers then sequenced parts of the genomes to look for patterns to suggest how related they were to one another. They discovered something amazing – the funnelwebs and the mouse spiders were closely related. Throughout the research process they also discovered three entirely new families of spiders that hadn’t been identified before.

The findings could help development new ‘general purpose’ antivenom that would be able to treat bites from a wide range of spider species.


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Photo Credit: Marshal Hedin

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