Amaurobiidae: funnel web spiders

This family has almost 700 world species of which three are found in the UK, all from the genus Amaurobius. They are large, robust spiders who produce cribellate, 'fuzzy' silk. They are nocturnal and live most of their lives hidden in silk-lined funnels in crevices in walls, tree trunks, ivy covered walls, or under logs and stones. Funnels are easily spotted as their entrance is surrounded by a messy array of lace-like silk threads extending onto the surrounding area. The silk is bluish when freshly laid and it immediately identifies its owner before you have even seen the spider. Passing insects get tangled on the threads and the resulting vibrations alert the spider sitting in her retreat. She springs out of her retreat, localises the insect and quickly bites a leg. Once she gets a good hold, she pulls the insect into her retreat.

Carding silk
Amaurobius similis often lives inside houses, and if you know where one of her retreats is, you could witness how she combs silk with the structures on her rear legs around the entrance to the retreat. Taking time to spin a few snares around the entrance each night.

An Amaurobius similis on the entrance of her funnel on the corner of a wooden fence.

Amaurobius female carding silk.

Eggs and egg sac guarding
Males mature in the autumn, when they wander in search of mature females (the top shot shows a male Amaurobius ferox, which tends to mature at the end of winter). When they find a female's web, they drum on to the threads with their abdomen and palps to signal his approach. Mating is a very swift affair.  Females lay their eggs in a silk cell on her retreat and sits by them.

Amaurobius sp. guarding her egg sac

Matriphagy
The female's care does not end with the guarding of the eggs in Amaurobius. When the spiderlings hatch, she opens the egg sac to facilitate their emergence. They she will sit by them and eventually produce a second batch of immature eggs, which the spiderlings will devour. This first meal substantially increases spiderling survival rates. She does not end her care them, as just before she dies, she collects the spiderlings under her body encouraging them to climb over her and feed on her body. Watch this video documenting this fascinating spider's maternal behaviour:

Amaurobius ferox male showing his remarkable palps, which appear to be holding white marbles.

A female Amaurobius female on her blue silk threads. 

Uloboridae: Cribellate orb-weavers

 Although not a particularly small family, only three species of Uloboridae are found in the UK, one of them, Uloborus plumipes only a recent colonist. They are very unusual spiders in many respects. The Uloboridae are cribellate spiders, they produce many fine threads which they comb using a structure on their rear legs formed by a row of short bristles, resulting in characteristic wool-like or frizzy threads.
 Uloborus plumipes the 'garden centre spider' (above) is typically found only inside garden centre heated glasshouse, and rests with her oversized and spiny forelegs together ahead of her, looking like a piece of debris on her orb web.

No venom
Another unusual feature is that, unlike most other spiders, they have no venom glands: they rely on quickly wrapping prey on silk and only bite once the prey is so immobilised.

Orb weavers
The orbs produced by Uloborus plumipes have a striking resemblance to Araneid webs, although other members of the family have more unusual asymmetric webs. Despite this, they appear to have evolved orb-weaving independently of the Araneae.

The orb web of Uloborus plumipes

The resting Uloborus with its characteristic posture on its orb-web.

The unusual spiky egg sac of Uloborus plumipes, which looks like a shrivelled piece of leaf or seed. You can see the woolly texture of the silk threads securing it.