First record of Ireland’s deadliest spider eating tiny protected mammal

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Galway Daily news Ireland's most venomous spider could be more toxic than believed

Scientists at University of Galway have published the first record of Ireland’s most venemous spider feeding on a pygmy shrew, a tiny protected mammal in Ireland.

It is the first time a member of the noble false widow spider species has been recorded preying on a shrew anywhere in the world.

The new study, published in Ecosphere, shows further potentially negative impacts of the spider on native Irish species.

The Pygmy shrew entangled in a False Widow Spider’s web. Credit: Dawn Sturgess

The extraordinary discovery was made by Dawn Sturgess at a home in Chichester in southern England when a small mammal was found entangled in a spider’s web on the outside of a bedroom window.

The small creature was later identified by the lengths of tooth rows as a pygmy shrew.

The shrew was still alive, but the spider’s highly potent venom was evidently taking effect as the shrew became increasingly incapacitated.

The spider was observed hoisting the shrew upwards into the rafters where it wrapped it in silk and fed off its meal for three days.

In Ireland the pygmy shrew is protected under the Wildlife Act (1976) and Wildlife (Amendment) Act 2000.

This is the third case in recent years of a protected vertebrate species falling prey to the noble false widow in Ireland or Britain, and this represents the eighth species of vertebrate known to fall prey to members of the false widow genus Steatoda.

The noble false widow now appears to be a regular vertebrate-eating spider.

Over the past seven years, the research team, led by Dr Michel Dugon at University of Galway’s Ryan Institute, have been studying a wide range of characteristics specific to the species including its venom, symptoms associated with their venomous bite, ecology and behaviour.

Dr Michel Dugon, Head of the Venom Systems Lab, Ryan Institute, University of Galway and lead author of the study, said: “This observation demonstrates further that the noble false widow is perfectly adapted to take down large prey, combining potent venom, extremely strong silk, and complex hunting behaviour.”

Dr John Dunbar, Irish Research Council Post-Doctoral fellow, Venom Systems Lab, Ryan Institute, University of Galway, and senior author of the study, said: “”he noble false widow is a very intriguing spider, and we have much to learn about it still.

“We are very grateful to the members of the public who share their observations with us. This allows us to understand better how this invasive species may impact us and our environment.”

The scientists at University of Galway are encouraging members of the public to email them at falsewidow@universityofgalway.ie to report sightings of the noble false widow spider.