Good News? Thousands of Giant Spiders on the Loose in UK

Thousands of giant spiders are on the prowl in the UK and that’s a good thing, according to the Chester Zoo, which is responsible for setting the arachnids loose.

The fen raft spider (Dolomedes plantarius) is widely distributed throughout Europe, but is designated “vulnerable” in England, where the little beastie was near extinction 20 years ago. The spider thrives in lowland fen and marsh areas, but degraded water quality and loss of suitable wetland habitats had brought the existing populations to the brink.

In 2011 the zoo, in collaboration with the Royal Society for the Protection of Birds, began the delicate process of rearing hundreds of baby spiders in individual test tubes.

“So they didn’t eat each other!” the zoo explains in a press release. “Our team delicately hand fed tiny flies to each of the hundreds of spiderlings using tweezers, day in, day out, for weeks on end in our bio-secure breeding facility. Eventually, the young spiders grew strong enough to be returned to their natural habitat, which our partners worked to restore, and we released them in their hundreds!”

Every year since, the conservationists check in on the re-established populations. They say 2024 is the best year on record, with an estimated 10,000 breeding females across the UK.

“Despite their large size, fen raft spiders are completely harmless to humans,” the zoo reassures. “They can grow to be around the size of an adult human palm, and can be identified by an eye-catching white stripe that runs along their body.”

The fen raft spider doesn’t weave a web (though females use their silk to create nests for babies). Rather, it perches on the water’s edge and gobbles up insects, dragonfly larvae, smaller aquatic spiders, and occasionally even tiny fish. Its presence is often indicative of a healthy ecosystem, and now they’re out there in the thousands.

Photo credit: Algirdas / Creative Commons