Scientists in Galway say their research on a species of spider, common across Ireland and the UK, has recorded another first.
The noble false widow has been found feeding on a bat pup in an attic in England.
The researchers at NUI Galway were contacted about the discovery, after conducting several years of investigations into the invasive creatures.
The noble false widow originated in the Canary Islands and Madeira but has been spreading worldwide in the last two decades. It is now one of the most common spiders found in urban settings in Ireland.
Shropshire based artist Ben Waddams found bats entangled in a spider's web, close to the entrance to a roost in his attic.
One was completely immobilised and was being eaten by a spider. A second, larger bat was also captured, but was released by Mr Waddams, before venom had been administered.
Scientists say it is the first time any species of false widow has been recorded preying on mammals.
Dr Michel Dugon, who oversees the research at NUI Galway, said it was a fascinating discovery.
"The noble false widow is a real treasure for us to research, it's a truly remarkable living organism", he said.
"A bat is several hundred times the weight of the spider and yet this species is capable of wrapping the prey in silk, injecting a toxic venom to immobilise its catch and then eating it.
"The spider does not have workable jaws to chew on their prey. Instead, they rely on their venom to paralyse and kill before they inject the prey with digestive juices from their stomach. They wait for those juices to dissolve the muscles and organs of the prey, and they then suck everything up 'like a broth'."
The noble false widow has also evolved very specific behaviour to use hoisting, to lift and leverage large prey above the ground. This allows it to bring it to a safe place, where other predators cannot access them.
The bat eating spider is the latest in a series of findings related to the invasive eight-legged predators.
Last year, Dr Dugon's team found the spiders could deliver bites that could require hospital treatment.
Before that, it was discovered that over 100 toxins found in the spiders' venom were common to those found in black widows.
It's thought a genetic mutation within the species may have made the false widow more adaptable to new environments.
They are thought to have made their way to Ireland in freight containers and have spread to all parts of the country since first being detected here in the late 1990s.