Irish scientists publish first record of noble false widow spider feeding on pygmy shrew

A noble false widow spider. Picture: JP Dunbar

Scientists at the University of Galway have published the first record of a noble false widow spider feeding on a pygmy shrew, a species of tiny mammal protected in Ireland.

It is the first time a member of this family of spiders, called ‘Theridiidae,’ has been recorded preying on a shrew in Ireland or Britain, and shows how the spider "is perfectly adapted to take down large prey".

It is also the first time any species of false widow spider to has been recorded preying on shrews anywhere in the world.

Researchers said 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 represents the eighth species of vertebrate known to fall prey to members of the spider. 

The study has found that the noble false widow "now appears to be a regular vertebrate-eating spider".

It added "the importance and novelty of" the report showing that small vertebrates are likely to be a more frequent component of the spiders' diet than previously thought, and it is first case of predation on shrews by the family of spider.

The discovery was made by Dawn Sturgess in West Sussex, England, when a small mammal was found entangled in a spider’s web constructed on the outside of a bedroom window. 

The ensnared 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 neurotoxic 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. In Britain, the species is protected under the Wildlife and Countryside Act, 1981.

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 Dugon, who is the Head of the Venom Systems Lab at the 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, senior author of the study added: "The 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 [e-mail] to report sightings of the noble false widow spider.

A noble false widow spider feeding on a shrew. Picture: University of Galway