Scientists at the University of Galway have released the first evidence of a noble false widow spider preying on a pygmy shrew, a protected species in Ireland. As per Science Daily, the protected pygmy shrew was trapped on a spider's web on a bedroom window, then immobilized and carried to its death by the invading spider.
Noble False Widow Spider Preying on Vertebrates
Spiders do not usually pose harm to humans and most mammals. However, the invasive species noble false widow (Steatoda nobilis) displays a habitual vertebrate predation behavior on lizards, bats, and now shrews.
In a new study, titled "Predation on a Pygmy Shrew, Sorex minutus, by the Noble False Widow Spider, Steatoda nobilis" published in the journal Ecosphere, researchers recorded a gruesome scene outside a bedroom window in southern England in which a female noble false widow spider subdued and fed on a pygmy shrew.
The pygmy shrew is more than three times bigger than the spider at about 5 centimeters (2 inches) in length and has a 4-centimeter-long tail, Science Alert reported.
Vertebrates may have been one of the targets of some spiders, but noble false widow spiders have difficulty tackling them with their webs. So, they use a combination of potent venom and strong silk to defeat their prey.
That is what happened to the pygmy shrew in Chichester in southern England that was recorded by Dawn Sturgess, a zoologist at the University of Galway. The video shows the spider with a small mammal ensnared in the silk outside of a bedroom window. The remains of the mammal, which were nothing but fur, bones, and skin, helped researchers identify it as a pygmy shrew.
Researchers report that the shrew was still alive on the web although it was only making slight movements at the beginning of its ordeal because of the spider's powerful neurotoxic venom known to cause rapid neuromuscular paralysis.
How the Spider Caught the Shrew
The team said that the spider was spotted going back and forth between the shrew and the rafters above the window, using silk to hoist the shrew upward around 25 cm. The spider had carried its victim into the rafters, largely out of sight, after 20 minutes. It enveloped the shrew in silk and dined on it for three days before dropping what was left out of its web.
It was unclear how the spider caught the shrew, but there is no evidence that it was an accident. Researchers wrote that it is the third report in five years of a noble false widow catching a vertebrate through methods linked to adaptations for habitual vertebrate predation.
Lead author Michel Dugon, also a zoologist at the University of Galway, said in a statement that the observation further demonstrates that the noble false widow spider perfectly adapted to tackle bigger prey using a combination of their venom, extremely strong silk, and complex hunting behavior.
Watch Science Alert's video of the noble false widow spider preying on a pygmy shrew.
RELATED ARTICLE: Invasive False Widow Spider Captures, Feeds on Very Large Mammals Like Bats in the UK
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