Vote for the beast that may be as ruthlessly predatory as us – the fen raft spider

The Guardian

30-03-2025

Meet an Olympian among Britain's 660 spider species: a palm-of-the-hand-sized arachnid that hunts in three dimensions and can even devour fish.
The fen raft spider (Dolomedes plantarius) is a magnificent ambush predator: harmless to humans but lethal if you're a pond skater, tadpole or even adult dragonfly.
And, while it was almost driven to extinction in Britain like every other slightly scary species, this brilliantly ingenious hunter has made a remarkable comeback.
The fen raft spider can run after prey. It can dive in pursuit of its quarry. And it can sprint along the meniscus, the tensioned surface of the water, to gobble up anything that dares cross its path.
It uses the surface tension of the water to detect prey, before skating, rowing or even sailing across the surface of the water to find its meal.
Araneae have been feared and discriminated against throughout history
When diving, it traps bubbles of air within a layer of dense, velvety hair on its mahogany-coloured body (with bright-cream or yellow stripes). The spider uses these to dive and survive underwater for at least half an hour. This is useful for evading larger predators.
The fen raft spider deserves your vote for its innovative lifestyle, athleticism and versatility alone.
But a vote for this magnificent invertebrate is also a vote for the much-traduced Araneae, who have been feared and discriminated against throughout human history. As Miss Spider from James and the Giant Peach (a shining example of invertebrate awareness in our spine-sided culture) put it: 'I am not loved at all. And yet I do nothing but good. All day long I catch flies and mosquitoes in my webs. I am a decent person.'
More than that, a vote for the fen raft spider is a declaration of hope in the midst of the sixth great extinction. It is a vote for the best side of humanity.
The fen raft spider is found across Europe but was only discovered in Britain in 1956. Here, it has always been ultra-rare – confined to the Pevensey Levels in East Sussex, around Crymlyn Bog in south Wales, and on Redgrave Fen bordering Norfolk and Suffolk.
Such isolated populations are highly vulnerable to extinction, with wetlands likely to become too hot or dry for the spider with global heating. So, since 2010, Dr Helen Smith has overseen a translocation programme (even rearing spiderlings in her kitchen) to reintroduce the fen raft spider to four new sites in Suffolk and Norfolk.
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The fen raft is now moving of its own volition into new suitable territory, thanks to the restoration of more appropriate boggy grazing marshes by conservation organisations including the RSPB, the Suffolk and Sussex Wildlife Trusts, Natural England, the Broads Authority, and the British Arachnological Society.
As a result, the number of sustainable fen raft spider populations has increased from three to 12 in Britain.
It is a popular nomination among readers, including Anna Maka, who is looking forward to a summer crawling through bogs searching for this spider as part of her PhD.
So vote for hope, vote for a habitable planet for all species, vote to cast aside prejudice and vote most of all for a small, wondrous animal that may be as ruthlessly predatory and ingenious as we are – the fen raft spider.
Between 24 March and 2 April, we will be profiling a shortlist of 10 of the invertebrates chosen by readers and selected by our wildlife writers from more than 2,500 nominations. The voting for our 2025 invertebrate of the year will run from midday on Wednesday, 2 April until midday on Friday, 4 April, and the winner will be announced on Monday, 7 April.