Giant spiders invade UK

Saucer-sized creepers spin their comeback web across the UK.

They’re back from the brink of extinction. Spiders the size of tea saucers are spinning their comeback web across the UK. A 15-year conservation project led by Chester Zoo is bringing the Fen Raft Spider back to the UK. Fen Raft Spider numbers reached 10,000 breeding females, 3,750 of which were found in the Norfolk area.

Population of giant spiders in UK had declined

The UK has lost 90 per cent of wetland habitats in the last 100 years, mainly due to human use of land and water. This loss of wetlands means many spiders have lost their habitat and has caused numbers to decline. The Fen Raft Spider can grow as large as a human hand or a small dinner plate. They are also cannibals. Chester Zoo’s project had to account for this and hand-rear the spiders in individual test tubes so they wouldn’t snack on each other. Spiderlings were fed tiny flies with tweezers every day until they were ready to return to their restored habitats. The project is now being hailed as a significant conservation success, with an estimated 10,000 breeding female arachnids back in the natural ecosystem.  

Why the UK needs more giant Spiders

According to spider brainiacs at Chester Zoo, Fen Raft Spiders help maintain healthy aquatic ecosystems by hunting fish and insects. They can skate across the water, scuba dive without air tanks for up to 20 minutes and devour small fish, tadpoles, flies and other surface insects like spiders, dragonfly larvae, and pond skaters. They are like little saucer-sized Bear Grylls splashing around in ponds.

RSPB Mid Yare site manager Tim Strudwick emphasised the spiders’ role in supporting aquatic diversity in grazing ditches. Fen Raft Spiders are impressive in size, but they play a critical ecological role.

Arachnophobes are understandably on high alert all across the country as these critters, which can spin webs up to 25cm in diameter, are gradually integrating back into the ecosystem. People are being told not to panic if they spot one skating across their local pond; rest assured, they are not venomous and are harmless to humans.

The history of the Fen Raft Spider (giant spider) in the UK

In 2010, only a few Fen Raft Spiders remained at three UK sites. Their habitat has gradually improved since then, and recent wet weather has boosted species numbers. They are still listed as a Vulnerable and Priority Species, with ongoing conservation efforts aiming to continue their recovery.

The RSPB Mid Yare nature reserves, located in Norfolk Broads, focus on protecting wetland habitats for various species, including the Fen Raft Spider. Tim Strudwick expressed pride in the reserve’s role in the spider’s recovery.

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