Segestriidae: Tube dwelling spiders

This is a small spider family of which only three species of the genus Segestria are found in Britain, only one of them widely distributed. They are elongated spiders, with only six eyes and the first three pairs of legs facing forward. They have a characteristic dark abdominal pattern, reminiscent of an adder's. They live in silk tubes in cracks in logs, walls, under stones and cliff faces. The tube opening is surrounded by at least six radial threads extending quite a way away, which act as signal threads to the spider sitting inside the funnel and are quite characteristic of the genus. The spider is active at night, when she comes out to her retreat's entrance, poised with her forward facing six legs touching the radial lines, awaiting passing insects.
Green fangs
Segestria florentina (top photo taken in Sheerness, Kent, courtesy of Robert Jaques) is a large spider that can reach 22 mm of body length. It is almost black with iridescent green chelicers. It lives near sea ports and it is thought to have been introduced from at least the 19th century with produce from the Mediterranean, from where it is native.

Maternal care
The female makes her egg sac inside her retreat and remains with her spiderlings until they disperse. Matriphagy, where the mother dies and the spiderlings eat her, has also been reported.

Theridiidae: Cobweb weavers

A large spider family, including some very famous world spiders such as the North American black widows (Latrodectus sp.), the Happyface spider (Theridion grallator) and the social spider (Anelosimus sp.). The 56 British species are small to medium spiders. They make irregular webs of criss-crossed threads with some of them stretched and loaded on one end with sticky dropplets, which break when an insect struggles to break free and lift the prey in the air like snares. The genus Episinus, however, produce the most remarkably simplified web, a 'H' shaped with four sticky threads connecting the spider to the ground and an over head support. Theridids have a relatively large, well marked abdomen with a diversity of patterns and colours.  This family includes one of the most fascinating examples of maternal care in spiders.

Powerful hunters
These spiders are able to throw sticky threads over prey to immobilise them. This ability, and their rapidly acting venom, makes them formidable hunters able to subdue much larger prey.

Steatoda bipunctata with immobilised Ectemnius wasp

Even the powerful and agressive male Anthidium manicatum couldn't escape Enoplognatha sp.

A wasp? No problem for Enoplognatha

Not even a honeybee. Note the typical web of Enoplognatha, tangled around a flower, ready to catch visiting insects, with the spider neatly hidden under the flower itself.

Enoplognatha doesn't even care about the chemical secretions of shieldbugs.

Colour polymorphism
Enoplognata  comes in several colour morphs. There is a white morph and one with a pink stripe. This is the pretty and rarer pink morph.

Stridulating males
Steatoda bipunctata males have a serration at the end of the cephalothorax which rubs against teeth at the front of the abdomen making an just audible stridulation which is used during courtship. In his field guide to the Spiders of Britain and Norther Europe, Michael Roberts writes:

I first heard this in use as a medical student. Quietly studying the anatomy of the brachial plexus, I became aware of a quiet sound from a guitar standing in the corner. My initial thought was that one of the well worn strings was very slightly creaking as if about to snap and I  clearly remember tensing myself for this not uncommon event. It turned out to be a pair of Steatoda bipunctata mating inside!

This is the male of Steatoda bipunctata. It waves it's large palps as it runs on the ground looking very ant-like. The female (top shot) has a look reminiscent of a fat tick, its cephalothorax almost hidden by her large, shiny abdomen.

Maternal care
Theridids make egg sacs that are attached to their web, or under a curled leaf retreat, and are often guarded by the females. Some species even carry the egg sacs attached to the spinners. The presence of females protects the eggs from predation, for example from ants. The mother will react to the presence of ants by relocating the egg sac more centrally on the web. Enopognatha guards her egg sac under a curled leaf and stays with the spiderlings until her death.
The small Theridion sisymphium female produces a bluish egg sac, which she guards. When the spiderlings emerge she will feed them  mouth to mouth with regurgitated food. Later, she will share prey with them until they are ready to disperse.

The wonderfully weird egg sac of Theridion pallens

The blue egg sac of Enoplognata sp.

The tiny Theridium pictum with her egg sac (note the screw head for scale). This species lives near other spiders webs and steals food from them. 

Enoplognatha with her brood inside a curled leaf.

Clubionidae: Sac spiders

The Clubionidae has 24 British species, mainly in the genus Clubiona. They are small to medium spiders usually of plain brownish colours, often with dark chelicers, and silky appearance. They have eight round eyes of similar size. Spinners are long, but converging, protruding from the end of the abdomen. They hunt mainly at night, without the help of a web, and spend the day in tightly woven silk cells they weave under stones, between leaves or in loose bark in trees and bushes. Species are difficult to identify in the field.



Egg sacs
The spiders mature in spring and summer and courtship is not very elaborate. Mating sometimes happens on the female's retreat. Females will also lay eggs within the retreat, where they guards their clutch and later, the spiderlings. Some species fold up or curl a leaf and lay their eggs in the fold, which the female then closes with white silk, with her staying inside.

Clubiona corticalis

Male Clubiona sp.

Female Clubiona in cell with spiderlings.

Male Clubiona sp. inside his cell between a window pane and leaf.

Clubiona with the chewed remains of her spider prey Amaurobius.

Pisauridae: Nursery web spiders

This is one of my favourite spider families, which displays a treasure trove of fascinating natural history. The family has just three medium size or large species in the UK, a terrestrial wandering hunter, Pisaura mirabilis, commonly known as the nursery web spider, and two semiaquatic species, the fishing spiders or raft spiders of the genus Dolomedes, able to run on water and dive to escape danger. I am yet to see a Dolomedes, but you can watch a video of the raft spider Dolomedes fimbriatus, a rare, protected species in the UK, with footage of courtship, egg sac building and maternal behaviour. Adult nursery web spiders do not make webs for hunting, but they build nursery webs for their young. The young (and some non UK species) do hunt with webs. These spiders have long, stout legs and they often hold the first and second pairs of legs extended together, like in the photo below.
Nursery web spiders are easy to recognise, they often have a pale line on their cephalothorax and parallel lines along the body. They are quite variable in the tone and colour of the lines, as you can gather from the individuals shown here.

Pisaura mirabilis basking in typical posture

Food for sex and feigning death

The reproductive behaviour of Pisaura mirabilis has attracted the attention of many researchers. When adult, males will catch an insect, wrap it in silk and search for females. It is thought this behaviour is elicited by the male coming across female silk drag lines, possibly impregnated with pheromones. When they find a female they present her the gift in their chelicerae while raising his body and front legs and palps (watch this video of the approach). If the female accepts the gift they will mate. Males without a gift have reduced chances of mating with females, but sometimes males 'deceive' females by wrapping some insect carcass or a piece of debris to offer the female. Presenting a silk wrapped gift increases the chances that mating will be completed before the females grab the parcel and run away. If the female shows aggression, the male can immediately become immobile (death feigning), while still holding his present. When the female renews her interest in the parcel the male comes back to life and resume mating.  

Male Pisaura mirabilis in another typical resting position. Note its swollen palps.

This male has captured a greenbottle fly.

Maternal behaviour
During the summer, in the lower level of meadows and other open, sheltered places, amongst grass and wildflowers, you might be lucky to come across a female Pisaura mirabilis carrying her large, white egg sac. She holds the egg sac on her chelicerae and palps until the spiderlings are ready to hatch, and despite her long legs, she looks like is walking on tiptoes with her cumbersome load. Once the young start to hatch, she loosens the egg sac and attaches it to a blade of grass. She then builds her nursery tent around the egg sac, where the spiderlings will reside for a while.

Female Pisaura mirabilis with fresh egg sac. Compare with the texture of the older egg sac on the top shot, note that the female on the top shot has a piece of egg sac covering between her chelicerae, so she might well have already loosen up the covering of the sac in preparation for building her nursery.

Nursery web with spiderlings. The spiderlings will form balls like in Araneus diadematus, and the balls also 'explode', with the spiderlings running away from each other when disturbed.

A female standing guard by her nursery web. The spiderlings will disperse after their second moult. Later in the summer, she may lay another batch of eggs.

Scytodidae: Spitting spiders

Spitting spiders are a small family, with just one British species, Scytodes thoracica. They are small (3-6 mm, female larger than the male) but easily recognisable with a dark markings like line drawings over paler background and clearly annulated legs. In the UK the spitting spider lives inside buildings, mainly in the south. It is a nocturnal wandering hunter, which does not build a web, and can be encountered prowling on walls. It has six eyes, with a characteristic arrangement. Males and females are very similar, and both the female genital opening and male palps are simple.



A glue shooting spider
The common name of Scytodidae comes from their unique method of capturing prey. They have a relatively large domed cephalothorax, larger than its abdomen, which holds paired glands which produce both poison and a glue-like substance containing silk. The glands open in the fangs and the spider is able to aim at potential prey at distance and shoot a mixture of glue and venom while swaying the fangs. The resulting paired zigzag pattern of gluey-silk strands entangles the prey and attaches it to the ground. The spider also uses its squirting action against other spiders larger than themselves.

Reproduction
Spitting spiders make a simple egg sac. The eggs are large, and each batch contains 20-35. The female holds the egg sac with her palps and spinnerets, and can feed while carrying the eggs. The spiderlings emerge from the egg sac, and hang from a web the mother builds from them. After about 10 days, the moult and disperse. They are slow developers, and long lived for such small spider, females mature at two to three years old and can live up to five years.

Scytodes thoracica on a wall

Feigning death when disturbed.

Face on view.

Blue lace weaver guarding her egg sac

I found this blue lace weaver, Amaurobius similis, under a flagstone. Its eggs, wrapped on bright white silk, forming a semitransparent large egg sac, which she will guard until the spiderlings hatch. I have written previously on the extreme maternal behaviour of this spider, especially its production of a second batch of eggs for her first brood of spiderlings to feed on, and the matriphagous behaviour of her spiderligs. To read more click here.

Pholcus before and after laying eggs

The first female Pholcus phalangioides laid eggs at the top of the porch last week. The gravid female I was following, which lives under a shelf in the outside toilet was still without eggs yesterday. This morning when I checked, she had laid. Check her abdomen before (below) and after laying (top).

Motherly candy-striped spiders

I find maternal behaviour of spiders fascinating, and I keep an eye for it whenever the opportunity arises. When repotting my gingko bonsai on the 2nd of September, I noticed a couple of rolled leaves. They contained web shelters of Candy Striped Spiders Enoplognatha ovata/latimana. One of them had a female with her egg sac, the other already contained spiderlings (above). I checked today again, both females were guarding their spiderlings. The first one approached the entrance of her leaf to check what was causing the disturbance, the spiderlings clustering together like Araneus spiderling balls. The spiderlings have been in one of the nests for almost two weeks. Will the presence of their mother increase their chances of survival? will the mother feed during this time? In the related genus Theridion (Enoplognatha ovata was previoulsy called Theridion ovatum) the presence of the mother guarding the egg sac appears necessary for egg survival (although there were some loses due to parasitism from a tiny wasp). The mother not only sits near the egg sac, attached to her by a silk thread, but she is on the alert, and will move the egg sac to the centre of the web when predators are nearby. Unguarded egg sacs are rapidly predated by insects (ants, earwigs) and other spiders. And what about the spiderlings? what do they have to gain from their mother's care? In the Happy Face Spider, Theridion grallator, the female loosens the egg sac allowing the emergence of the spiderlings, and then captures prey for her brood. The spiderlings are under the female care up to three months, until they disperse and feed on their own. The female might produce another egg sac if the first one is lost, but she will die by the end of September early October. The spiderlings will disperse and overwinter near the ground.

One of the females, in close contact with her egg sac (2/9/14)

More information

British Arachnological Society.

Nursery web spiders and their nurseries

The population of nursery spiders at the wildlife garden is particularly obvious now, as their nursery tents hang from their high positions from grasses and meadow cranesbill leaves, closely guarded by females. There are at least 20 nurseries scattered over the meadow at different stages of development. In some the spiderlings have already dispersed, after spending a few days safe inside their tents. This is what W.S. Bristowe had to say about the female after mating takes place:

During the first half of June the female may be see trundling along with a huge light-coloured egg sac under her sternum which is attached to her spinnerets by threads and is held in her chelicerae. At about the time the eggs are beginning to hatch, she loosens the outer covering and attaches it to a blade of grass. The she weaves a tent over it on the outside of which she stands on guard [...] The young emerge in late June or early July, after moulting once inside the egg sac. Now they cluster together in a ball inside the tent for a few days before moulting for a second time and dispersing.

I found the first nursery with already emerged spiderlings on the 20th of June. Bristowe was of the opinion that Pisaura will have two batches of eggs. Although the female below was carrying an egg sac on the 4th of July, I am not sure if this represents variation on the date of reproduction of different individuals as they mature, or evidence of a second batch.

Female carrying her disproportionate egg sac. They appear to walk on tiptoes holding it. I don't think the female is able to hunt while carrying her egg sac.

This spider has a fresh nursery web and appears to be manipulating the egg sac to allow the spiderlings to emerge.

Unlike the neat, smooth new tents holding clustered spiderlings the tent above has a few holes (made by the female?) allowing spiderlings to disperse. The spiderlings are clustered forming a ball just visible at the top right hand corner of the nursery tent.

The spiderlings are often clustered together in a ball like garden spider ones. The ones above look like they are ready to leave their tent.

If you click to enlarge the photo you might be able to see some tiny spiderlings on top of the tent already leaving.

I haven't found any information as to the function of the nursery web. Certainly it keeps the spiderlings dry during rain, and the mother is often found underneath also during poor weather. It could offer protection from parasites or predators. Many predatory insects will readily take spiderlings, including wasps, and it appears that the nursery web is not totally wasp-proof, as these photos on Flickr show.

Spider eggs and egg sacs

Spiders make remarkable mothers. One of the most widespread maternal behaviours is the more or less elaborate construction of an egg sac, and many species are making them at this time of the year. The mother wraps a batch of eggs - which might be the only one she will produce during her lifetime - into a neat parcel kept together with silk. The egg sac can protect the eggs from parasitic wasps, or from predation - sometimes from other spiders. In addition, egg sacs are often guarded by the mother, like the Neriene montana above (28/05/2014) or Garden spiders (below), Araneus diadematus, which guard their large egg sacs until they die at the end of autumn (30/10/2011).

Holding the egg sac is another maternal behaviour. An example is Pholcus phalangioides, the splindly daddy long-leg spider. She makes a simple egg sac, with the eggs clearly visible through the lax packaging. She keeps the eggs on her mouthparts until the spiderlings hatch (22/07/2009).

Being mobile spiders, wolf spiders and nursery web spiders actually carry their egg sac with them wherever they go. This allows the eggs to develop faster, as they warm up when spiders bask in the sun.

Wolf spider, Pardosa sp. carrying her egg sac (31/05/2011), attached to her abdomen.

Nursery web spider carrying its large egg sac (19/06/2011).

In the family Gnaphosidae, the female not only guards the eggs, but she makes her egg sac inside a folded up leaf, locking herself inside with the eggs (19/07/2010):

But egg sacs are often found alone. Some of them have a stalk, like those of the genus Ero, also distinctive by their covering of coarse red silk (7/04/2013):

Others are truly unique, and is the best way to identify the species, like the sputnik-like egg sac of Paidiscura pallens, a tiny spider (28/05/2014).

Eggs vary in colour, I love the soft pink eggs of Steatoda bipunctata (28/05/2014)...

 ...and also the baby blue silk of Enoplognatha sp., revealed here while picking apples (30/08/2011):

These are just a few examples, from common spiders you can find in your own garden, which illustrate some of the diversity of spiders.