Spectacular Spiders

There are over 650 different species of spider in the UK, ranging in size from the tiny money spider, the Minute Maro (Maro minutus), to the Cardinal Spider (Tegenaria parietina), which has a leg span of more than 10 centimetres. The heaviest spider in Britain is the Four-spot Orbweaver (Araneus quadratus) which can weigh up to 2.5 grams!

Spiders are not insects. They belong to a class of animals known as Arachnids, which also includes harvestmen, scorpions, mites and ticks. However, like insects, they are invertebrates which means they don’t have a backbone. Most adult arachnids have four pairs of legs and two pairs of mouthpart appendages: pedipalps and chelicerae. Pedipalps are adapted for feeding, defence and courtship. The chelicerae are primarily used for biting or chewing and it’s through these modified mouthparts, that spiders deliver the venom that subdues and kills their prey. It’s unusual for a spider to bite a human, and even rarer for a spider bite to cause any severe reactions in the UK.

In the UK, all species of spider are carnivorous, feeding on insects, other spiders and sometimes even scavenging dead prey. You might assume that all spiders catch their prey in webs, however some spiders use more active methods when hunting. The Dune Wolf Spider (Xerolycosa miniata) will stalk and then chase their prey. Others, like the Flower Crab Spider (Misumena vatia), ambush their prey by changing colour to match the flower it’s hunting on, allowing them to grab unsuspecting prey when they land to feed on the flower’s nectar.

All spiders can produce silk, and as mentioned, it’s not always used for hunting. Spiders like the aptly named, Nursery Web Spider (Pisaura mirabilis), create nurseries for their young with their silk and others like jumping spiders (family Salticidae), build ‘pup tents’ which are used to shelter, moult and lay their young in. These web structures can be impressive works of art and it’s worth taking a moment to appreciate the workmanship of the spider who crafted it.

Why are spiders important?

The UK is home to a number of globally rare and special species of spider. The unfortunately named Horrid Ground-weaver (Nothophantes horridus) may be one of the rarest spiders in the world and it can only be found in Plymouth, Devon.  The Ladybird Spider (Eresus sandaliatus) was thought to be extinct in Britain until it was rediscovered in 1979 and is local to Dorset. The Fen Raft Spider (Dolomedes plantarius) is one of our largest species of spiders in the UK and can be found on only seven sites across Norfolk, Sussex, Suffolk and Swansea in Wales.

Spiders are important for controlling insect populations. They feed on the insects we consider pests, like aphids, and keep insect numbers down in our houses and in agricultural environments. They themselves also provide an important source of food for birds, small mammals and even some species of wasp and ant. Spider silk is also a valuable material and of interest in research as it’s tough and stronger by weight than steel, as well as elastic and waterproof.

How can you support spiders?

Spiders deserve to be celebrated and their important role in our ecosystem recognised. Buglife is involved in a number of species recovery projects that are focussed on conserving species such as the Horrid Ground-weaver, the Ladybird Spider and the Fen Raft Spider.

Support Buglife’s campaigns to protect important spider habitats like Swanscombe Marshes, which is home to the Critically Endangered Distinguished Jumping Spider (Attulus distinguendus), and Middlewick Ranges, where a quarter of all the UK’s spider species have been recorded.

Join a local recording scheme and submit your sightings to the British Arachnological Society or download the iRecord app and get recording!