Largest spider in the UK – Raft spider

Posted on Apr 11, 2012 in Size


Largest spider in UK

It may not challenge heavyweights like the Goliath bird eating tarantula or the Hercules baboon spider when it comes to size, but this diminutive arachnid is a titan in its own right; it is the largest spider found in the United Kingdom.


How big can it get?

As with most spiders, the female is the larger sex. Its body can measure as much as 22 millimetres (less than an inch) with its legs reaching 7 centimetres (nearly 3 inches). The male is substantially smaller.


What does it eat?

This semiaquatic creature dines on small water-based insect larvae, sticklebacks, tadpoles and other small spiders, which it can detect using its highly sensitive front legs.


How does it hunt?

Its body is covered in short, water-repellent hairs which allow it to walk on water or rather it skates across the surface of ponds and marshes where it can snatch prey. It can also submerge itself below the water, although this is generally used as a defensive technique.


How dangerous is it?

Its size might give you a shock, especially if you’re British and only used to seeing tiny creepy crawlies, but otherwise the raft spider poses no threat to us. However for a truly dangerous ‘harmless’ spider, look no further than the enormous Aussie huntsman spider; an eight -egged monster the size of a dinner plate who think nothing of hanging out in your car… whilst you’re driving.


How many are left?

Raft spiders are fairly commonplace across Europe and into Russia. However, there are select species whose survival is threatened. The fen raft spider is actually the most endangered of any species in the U.K.


Anything else?

It may be small but its heart is large. Female raft spiders take great care in looking after their young, from frequently dipping its egg sac in water to keep unborn babies moist to guarding a specially built nursery for up to a week after birth, moves that help aid the safety of hatchlings.

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