Giant spiders 'size of human hand' have record breeding year in UK

Experts at Chester Zoo have said spiders the size of a human hand have had a record breeding year in the UK, with thousands of the fen raft spider

Huge spiders have had a record breeding year in the UK, experts have said.

Chester Zoo released thousands of fen raft spiders, which grow to be as big as a human hand, a decade ago. There are now over 10,000 breeding females across the UK, said to be an all time high.

“Ten years ago we helped release thousands of giant spiders back into the UK,” Chester Zoo said. "The fen raft Spiders were bred right here at the zoo, and we're super happy to report there are now more than 10,000 breeding females and they've just had the biggest mating season on record!"

Fen raft spiders will send a chill through the spine of arachnophobes, but the creature is completely harmless. The zoo also said they are really important for healthy aquatic ecosystems.

This is because fen raft spiders are semi-aquatic and are named after their ability to run across water when they are hunting their prey. Unlike many other types of spider, fen rafts hunt their prey instead of trying to trap them in a web.

Tiny hairs on their legs can detect even the smallest of vibrations on the surface of the water, triggering the spider to run across water and close down its prey. They tend to eat other spiders, damselflies, dragonfly larvae and pond skaters and have even been recorded catching tadpoles and fish.

Despite being important for the ecosystem, fen raft spiders nearly went extinct due to destruction of the wetland homes it inhabits. Chester Zoo reared hundreds of baby spiders in individual test tubes to save the species as part of a breeding programme undertaken with the RSPB.

Chester Zoo said: "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!

RSPB Mid Yare nature reserves site manager, Tim Strudwick, said: “The Fen Raft Spider is one of the UK’s rarest invertebrates and we are proud of the role our reserves and teams have played in its recovery.

"These spiders have an important role in maintaining the rich aquatic diversity found in the grazing ditches on our reserves. The females are impressive in size, but also beautiful – they are truly special to see!”