15mm female Meta menardi, with a leg-span of 68mm, found in Wouldham, Kent, beneath a manhole cover for a residential sewer outlet. 16th June 2019.
European Cave Spider (Meta menardi)
Also known as the Large Cave Spider and the Cave Orb-Weaver. There are two very similar species of Cave Spider in the UK which can usually only be accurately distinguished by very close examination of the reproductive organs, Meta menardi and Meta bourneti. The European Cave Spider, Meta menardi, is one of the UK's largest spiders with a bulky, round, oval body. Meta menardi typically reaches around 10-13mm for males and 12-17mm in body-length for females, with a leg-span of around 50-70mm. Sometimes larger specimens can be found. These gentle giants are capable of giving a sharp nip if provoked but are very reluctant to bite and can usually be handled gently without issue. Cave Spiders are members of the Tetragnathidae family of Long-Jawed Orb-Weavers. Both species of Cave Spider are large, long-legged spiders, usually with glossy abdomens.
Although widespread across the UK Cave Spiders are rarely encountered spiders due to their very specific habitat requirements. Meta menardi are considered as widespread in Britain, but uncommon. Meta bourneti are considered to be nationally scarce, and most specimens are found in the south and east of England.
Adult Cave Spiders are photophobic, meaning they are repelled by light and prefer to live in complete darkness, often in damp locations such as sewers, tunnels and caves. Whilst humans rarely visit caves Cave Spiders are still frequently found living in other suitable habitats, such as railway tunnels, mines, damp cellars, under manhole covers and occasionally in gardens under decking. They have also been recorded living in dense ancient woodland, in large hollow oak tree-trunks. Cave Spiders build orb-webs of up to 30cm in diameter, although the spiders are usually seen waiting beside the web, on the walls of their surroundings, rather than in the web itself.
The European Cave Spider usually lives for 2-3 years. After mating in the summer adult females deposit their large, teardrop-shaped, white egg-sacs in autumn, usually from September to November, fairly near the entrance to the cave, where the young spiderlings will develop. These large pendant egg-sacs are suspended from the ceiling of the cave and measure 1.5-3cm in width. Each egg-sac can produce up to 200-300 spiderlings. The spiderlings will hatch in late winter or early spring, from the end of January until the start of April, and will remain in the egg-sac, feeding on the yolk, until after their second moult. In the spring or early summer the spiderlings will disperse from the cave exit via ballooning into new areas. Unlike adult Cave Spiders the juveniles are positively phototaxic, meaning they are actually attracted to light. This encourages them to leave the cave and disperse in search of new territories to colonise. In most cases female Cave Spiders will outnumber males on a ratio of at least 3:1 or 5:1. Females also usually live longer than the slightly smaller males. Cave Spiders have a fairly low tolerance of cold temperatures and are most frequently encountered in areas that do not see temperatures drop much below 7 degrees Celsius.
Cave Spiders, especially Meta bourneti, with its subtle or faded abdominal markings, are often confused with False Widow Spiders. One easy way to separate the two is to look at the legs. Meta species have clearly visible leg-spines that are absent from all Steatoda species, and all other spiders from the family Theridiidae.
Distribution of Cave Spiders in the UK, 2024.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
The large female Meta menardi, pictured above, was one of 13 specimens found in a cave in Somerset during my search in August 2022. 7 specimens were adult females and 6 specimens were sub-adults. No egg-sacs were found at this time of year on my visit, although egg-sacs were found around this time of year by other spider hunters searching for Cave Spiders at different locations.
There is one other orb-weaving spider, also from the family Tetragnathidae, that can often be found sharing the same dark, damp habitat as the Cave Spiders, the Shaded Orb-Weaver, Metallina merianae.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Within cave habitats there exists a measured degree of association to the subterranean conditions. This degree enables the distinction of three different groups of cave dwelling species.
Troglobites - these are the most specialised of the cave-dwelling organisms and are usually found in the deepest areas of subterranean environments. Troglobites spend their entire lives living in these areas of total darkness and have adapted to these unique habitats. Troglobites often show such adaptations such as depigmentation, a malformation or complete absence of eyes, elongation of appendages, and a reduced metabolic rate in line with the reduction of prey availability.
Troglophiles - these species can be found both above and below ground, and some stage of their life-cycle is usually above ground. As such they tend to show subtle, or no obvious adaptations to a subterranean existence.
Trogloxenes - these are species that usually exist outside of caves, but can on occasion be found at the entrance to caves. Trogloxenes are unable to exist entirely in subterranean habitats.
Cave Spiders, both Meta menardi and Meta bourneti, fall into the category of troglophiles. Although adult Cave Spiders will often choose to live within cave habitats, the young juveniles will readily disperse outside of the cave environment in search of new territories.
Immature Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Caves and subterranean habitats can often be divided into three separate zones. Firstly there is the entrance zone which consists of the area that is regularly exposed to direct sunlight. The entrance zone is the most nutrient rich zone where there is plenty of prey for its inhabitants. Secondly there is the twilight zone. The twilight zone never receives direct sunlight but still has low levels of light that the human eye can just about adjust to. The twilight zone has a much lower number of organisms that can live there permanently. Thirdly there is the dark zone or deep zone. The dark zone has no visible light at all to the human eye. Here very few organisms can survive unless they are specifically adapted to do so and prey is very scarce. The dark zone is often by far the largest zone in a cave system. Adult Cave Spiders usually build their webs in the twilight zone, but Meta menardi specimens can also sometimes be found in the dark zone. One study from 2012 found that Meta menardi specimens could be recorded as deep as 69 metres into the dark zone. (See page 349) Female Cave Spiders of both Cave Spider species always produce their egg-sacs in the twilight zone, and this is where the spiderlings usually spend the first 1-3 moths of their lives. Egg-sacs are never deposited more than 10 metres from the cave entrance. The number of Cave Spiders found in any cave drastically reduces once you start looking past 10-12 metres into the cave. Flying insects, that orb-weavers, such as Cave Spiders, primarily prey upon, are very seldom caught in the dark zone. Juvenile Cave Spiders usually build their webs in the entrance zone, or the beginning of the twilight zone. - LINK
With the low metabolic rate of most spiders, and the low dependency of vision for many species, it is easy to understand how spiders can adapt well to a subterranean existence. As of 2017 there were around 47,000 species of spider recognised throughout the world. There are more than 1000 of these species that can be categorised as Troglobites, spending their entire lives in complete darkness. There are a similar number of Troglophile species that usually spend some stage of their life-cycle living in a dark environment in the twilight zones of caves and other underground habitats. In Britain and Europe there are around 195 species of spider that can be categorised as Troglobites and around 291 species of spider that can be categorised as Troglophiles.
Apart from the Cave Spiders, and the Shaded Orb-Weaver, which are both Meta and Metellina representatives from the family Tetragnathidae, other spiders from Britain and Europe that can be found in caves and other subterranean habitats come from several different families. These include around 22 species from the Money Spider family Linyphiidae, 56 species from the Woodlouse-Hunting family Dysderidae, and 50 species from the Scaffold-web Spiders, or Cave Cobweb Spiders from the family Nesticidae.
Although in the UK there is a large overlap of the distribution of all three orb-weaver species that are found in caves they each seem to have their own niche preferences. Studies have confirmed that Meta menardi and Meta bourneti hardly ever, if ever, share the same cave site. The European Cave Spider, Meta menardi, does sometimes share caves with the Shaded Orb-Weaver, Metallina merianae, but Metallina merianae are usually found much closer to the cave entrance. Meta bourneti is more tolerant to variations in microclimatic conditions and is therefore more adaptable to a limited range of habitats. In areas where both species are present though, and in cave systems where conditions are more favourable, Meta menardi is believed to out-compete Meta bourneti. Studies have shown Meta menardi have less tolerance to cold temperatures and require slightly damper and more humid conditions than Meta bourneti. The closer to the entrance of the cave its inhabitants get the more variation in temperature and conditions they would experience. This may be why Meta menardi can sometimes be found in the dark zone of caves, where conditions are very stable and unchanging. During the hottest periods of the year both species of Cave Spider may move slightly deeper into the caves where conditions are less affected by external temperature variations.
Immature Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Life-Cycle of Cave Spiders
Once hatched inside the egg-sac the tiny spiderlings have their first moult fairly quickly. The spiderlings remain within the egg-sac, feeding from the eggs they hatched from, until their second moult. At this stage the spiderlings leave the egg-sac in mass and gather fairly closely the outside of the egg-sac. Here they may stay for between 1-3 moths before dispersing and heading towards the light. In cave habitats this will mean heading towards the entrance of the cave. Some specimens will build their webs at the entrance to the cave but the majority of the spiderlings will disperse by letting out a line of silken thread and ballooning with the wind.
Once dispersed the spiderlings will typically build their orb-webs in bushes and shrubs and remain feeding above ground until they've had their 3rd or 4th moult. After this the young Cave Spiders will begin returning to subterranean habitats, where they will live the remainder of their days in subterranean habitats or in sheltered locations with complete darkness. Cave Spiders reach maturity after their 7th moult, at which point they are ready to mate. Following mating the adult female will produce her large egg-sac, which can contain up to 200-300 eggs. The egg-sac is usually suspended from the roof of the cave but can also be fixed near the top of the sides of the cave too. Once the egg-sac is produced the adult female will guard over it until she dies. Most females will live long enough for the young spiderlings to hatch and have their first, and sometimes their second, moult. It's not clear whether males die immediately after mating or if they move on to mate with additional females. With females largely outnumbering males in most habitats I suspect the males probably mate with more than one female, especially in habitats with large densities of Cave Spiders.
Variations in the major life-cycle stages of both UK Meta species. Based on data from studies by Stefano Mammola and Marco Isaia in Caves in Italy, 2014.
Although this diagram I have put together is based on data from studies in Italy it is believed that the typical pattern of behaviour would be very similar for Cave Spiders in the UK.
Summary
Adult females of both Cave Spiders can be found all year round.
Adult males are usually only seen between July and September for Meta Menardi and August to January for Meta bourneti.
Egg-sacs for Meta menardi are produced earlier but hatch later than those of Meta bourneti.
Immature Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Web structure comparison between Metallina merianae and Meta menardi. Diagram inspired by original illustration by Daniel Simonsen & Thomas Hesselberg.
Diet and web structure of Cave Spiders
The diet of Cave Spiders consists of both flying prey, that is caught in their orb-webs, and crawling prey, that they catch either by patrolling the walls near their web, or by catching as the crawling invertebrates that pass by their webs. Prey can include sheltering moths, gnats, craneflies, slugs, smaller spiders, and myriapods such as millipedes, centipedes and woodlice. During the winter months prey can be very scarce within the depths of caves and tunnels and Cave Spiders may go several months without feeding. The orb-webs of most spiders are usually constructed to almost exclusively catch flying prey. The orb-webs of Cave spiders are slightly unusual in their construction though and are probably built to aid in the capture of both flying and crawling prey. The webs of Cave Spiders have relatively small capture spirals to capture flying prey. They have very few, if any frame threads. Cave Spider webs also have more radii threads than other Tetragnathidae, that radiate from the centre of the web and fix directly to the cave walls and ceiling, serving as mooring threads. The majority of radii threads in the webs of other tetragnathids fix to the frame threads, which are then fixed to the cave walls and ceiling by mooring threads. It has been hypothesised that in the webs of Cave Spiders, the nature of the radii threads, that fix directly to the cave walls, probably serve as trigger lines to alert the Cave Spider to the presence of wandering prey on the cave walls and ceiling. - LINK
Female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
A tale from my searches for Cave Spiders
I went in search for Cave Spiders in caves located in Dorset, during August 2022. During these searches I managed to find one adult female Meta menardi specimen, one adult male and one sub-adult female. Unfortunately I had accidentally left my headtorch in the car, which was parked about a mile away from the caves. The light on my flash diffuser had quickly died and this cave was incredibly dark. On top of this my flash gun batteries were also dying, which meant I had to wait in almost total darkness for about one minute in between each of the photos that I took, whilst I waited for my flash gun to recharge for the next shot.
During each shot I sat on the damp floor patiently waiting for my flash gun to sort itself out. It wasn't long though before a couple of hikers decided to also check out the cave I was waiting in. Naturally they thought they were alone and as they shone their torches around the cave they suddenly pointed their torches at me, sitting motionless on the floor of the cave. I swear I've never heard two large grown men scream as loudly as these two guys did when they suddenly saw me in the cave. They didn't give me any chance to explain what I was doing there, they just ran out of the cave screaming! lol
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
Adult female Cave Spider, Meta menardi, photographed in a cave in Somerset, 12th August 2022.
12mm adult female Cave Spider, Meta menardi, photographed in a Dorset cave, 8th August 2022.
12mm adult female Cave Spider, Meta menardi, photographed in a cave in Dorset, 8th August 2022.
12mm adult female Cave Spider, Meta menardi, photographed in a cave in Dorset, 8th August 2022.
12mm adult female Cave Spider, Meta menardi, photographed in a cave in Dorset, 8th August 2022.
12mm adult female Cave Spider, Meta menardi, photographed in a cave in Dorset, 8th August 2022.
10mm female Cave Spider, Meta menardi, photographed in a cave in Dorset, 8th August 2022.
10mm female Cave Spider, Meta menardi, photographed in a cave in Dorset, 8th August 2022.
10mm female Cave Spider, Meta menardi, photographed in a cave in Dorset, 8th August 2022.
13mm adult male Cave Spider, Meta menardi, with Cranefly prey, photographed in a Dorset cave, 8th August 2022.
13mm adult male Cave Spider, Meta menardi, with Cranefly prey, photographed in a Dorset cave, 8th August 2022.
13mm adult male Cave Spider, Meta menardi, with Cranefly prey, photographed in a Dorset cave, 8th August 2022.
13mm adult male Cave Spider, Meta menardi, photographed in a Dorset cave, 8th August 2022.
1mm juvenile Cave Spider, Meta sp. photographed on its first day exiting the egg-sac, 11th September 2024.
Raising Cave Spiders in captivity
On 30th August 2024 my wife felt compelled to rescue a couple of egg-sacs, belonging to Meta species, that were being evicted from a disused garage that was being cleared out. Following my request my wife brought the egg-sacs back home for me. My plan was to try and hatch the egg-sacs and raise the spiderlings in captivity. I hoped that once the spiderlings reached a significant size I could introduce this species to the drainage system in my garden. When I first saw the egg-sacs one egg-sac was already slightly darkened and I suspected that some spiderlings could emerge very soon.
Unfortunately by the 10th September, nearly two weeks later, no spiderlings had emerged and the egg-sacs hadn't changed in appearance. It was at this stage that I decided to open up the darker egg-sac myself. With some species of spider, including Raft Spiders and Nursery-web Spiders, the spiderlings are unable to exit the egg-sac themselves. Once the eggs hatch the adult female spider bites into the egg-sac and tears a hole that allows the spiderlings to exit the egg-sac. I wasn't sure whether Cave Spiders also needed this intervention for the spiderlings to exit the egg-sac but I decided to take the chance. Upon opening the egg-sac I discovered several dead spiderlings within. The egg-sac also contained quite a few unhatched eggs too. When I lifted the egg-sac upside down one tiny 1mm spiderling emerged. I chose to leave the solitary spiderling in the same container as the egg-sacs in the hope that maybe it could feed from the remaining eggs or even the dead spiderlings from its own egg-sac. I also introduced some tiny greenfly and other tiny invertebrates that may also provide a source of food for the spiderling.
12th September - Since taking these egg-sacs into captivity I have researched Meta species extensively and my knowledge and understanding of both of Britain's Cave Spiders has improved considerably. The eggs of Cave Spiders take considerably longer to hatch than I initially thought. Meta Menardi can take 3-6 months for the spiderlings to emerge from their egg-sac. Meta bourneti can take 1-5 months. Egg-sacs for Meta menardi are usually produced from the start of August until the end of October, and the spiderlings can emerge anytime between the start of February and the end of April. The egg-sacs of Meta bourneti are usually produced later in the year, from the start of October to the start of December. Meta bourneti spiderlings usually emerge in January and February. With my two egg-sacs being found at the end of August it is far more likely that they'll be Meta menardi than Meta bourneti. I can now expect the egg-sacs to hatch anytime from February onwards. Keeping the spiders indoors through the winter, at temperatures higher than they would naturally experience in caves or other subterranean habitats, could result in the spiderlings developing at a faster rate and the spiderlings may emerge earlier than they would usually do in the wild. I am now also aware that the adult female Cave Spider often dies before her spiderlings emerge from the egg-sac, and therefore the spiderlings probably do not need any assistance from the adult female, or from myself in the case of these captive specimens, to exit the egg-sac.
3.5mm juvenile Cave Spider, Meta sp. photographed at 7 months of age. 12th April 2025.
12th April 2025 - Unfortunately no other spiderlings ever hatched from the egg-sacs that I rescued. The one surviving spiderling grew extremely slowly over the next 7 months. For the first few months the spider did not appear to feed at all. Eventually it starting taking tiny greenfly and slowly began to grow. By 7 months of age the spiderling was still just 3.5mm in length but was a much better feeder than previously. The spiderling still only ate every couple of weeks but exhibited a definite preference for small gnats, mosquitos and midges over all other prey offered.
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15mm female Meta bourneti, with a leg-span of 67mm. 8th December 2022.
Bournet's Cave Spider (Meta bourneti)
Britain's other cave spider, the nationally scarce Meta bourneti, is very similar in appearance to Meta menardi, and can be difficult to distinguish. Adult Meta bourneti can show some possible distinctions from Meta menardi though. Adult Meta bourneti are typically duller and less colourful in appearance, and usually have much fainter markings on their abdomen. Meta bourneti do not usually retain significant dark rings, or annulations, on their legs as they mature. However, the legs of adult Meta menardi usually do retain quite obvious dark rings, and orange rings, throughout their lifespan. Where dark rings are seen on the legs of Meta bourneti they are far more subtle than those found on Meta menardi. Adult Meta bourneti are a similar size to Meta menardi, with males having a typical body-length of 10-13mm, and females reaching around 13-16mm. A close inspection of the epigyne or pedipalps is needed to be totally sure of species though. This species is also widespread across much of Europe and north Africa. Meta bourneti wasn't recorded in Britain until as late as 1941. Although it is possible that this species may have been overlooked until then some sources claim that due to Meta bourneti being largely confined to southern areas in the UK it is likely that the Bournet's Cave Spider is an introduced species to Britain from mainland Europe.
More views of the 15mm female Meta bourneti, 8th December 2022.
Like the European Cave Spider, Meta menardi, the Bournet's Cave Spider, Meta bourneti, builds its orb-webs above ground in vegetation until the 3rd or 4th moult. At this stage the Bournet's Cave Spider starts to darken in appearance and the leg-annulations become far less obvious. - LINK
One large and quite well known colony of Bournet's Cave Spider in the UK can be found within multiple vaults at Highgate Cemetery, in north London. When surveyed in 2021 this colony was found to consist of over 100 specimens and was even featured on the BBC's Countryfile TV show. - LINK 1 LINK 2 LINK 3
St Denis' Church, East Hatley, Cambridgeshire, 9th September 2022
Bournet's Cave Spiders at St Denis' Church, at East Hatley, Cambridgeshire
In 2006 a small colony of the nationally scarce Meta bourneti were at risk of being left homeless when an old air-raid shelter, where they were discovered in Papworth Everard, Cambridge, was scheduled to be demolished to make way for development. Thankfully a rescue and relocation plan was put into action by Rob Mungovan, who at the time was the Ecology Officer at South Cambs District Council. The Cave Spiders were transferred to an underground room, beneath St Denis' Church, some 11 miles away in East Hatley. The identity of these large orb-weavers was officially confirmed, by microscopic examination, in the summer of 2006 as Meta bourneti by Brian Eversham, entomologist and pervious CEO of the Beds, Cambs and Northants Wildlife Trust. Despite the "nationally scarce" status of Meta bourneti there are actually more records of the rare Meta bourneti in Cambridgeshire than there are for the far more common European Cave Spider, Meta menardi. Since the 2006 discovery of the Cave Spider colony in Papworth Everard there were numerous further sightings of Cave Spiders being discovered in many different dark locations in Cambridgeshire. These included a Gamlingay WWII bunker, drains at Madingley Cemetery and even phone equipment boxes in Arrington. Although proving far more numerous than previously expected none of the other sightings were officially examined and identified to a species level unfortunately.
At the time of the transfer St Denis' Church was a local, disused, medieval church in the small, rural village of East Hatley, Cambridgeshire. Beneath the Grade II* listed building lay a disused furnace chamber that would provide an ideal hideaway, for these dark-loving spiders, where they could continue their existence undisturbed. St Denis' Church was situated in a small local nature reserve and it seemed the ideal location to be used as a receptor site for such a relocation. These rare spiders would share the church with other scarce species, including Brown Long-eared Bats, Plecotus auritus, that roost in the building, and Great Crested Newts, Triturus cristatus, that spend some of their terrestrial life in the church's cellar. The tiny furnace chamber is a dark, damp, underground storage room with limestone walls and a clay covered floor. With no windows in the furnace chamber there is no light entering this underground room, and here the spiders are very rarely ever disturbed by human visitors. Hidden away from the rest of the world the Bournet's Cave Spiders have managed to thrive since their introduction, and successful breeding takes place yearly.
On 9th September 2022 I was given the privilege of surveying and photographing these special spiders. The idyllic old church is situated on the grounds of a small nature reserve. The old wooden door at the entrance to the furnace chamber remains locked to the public, but proudly displays a notice informing visitors of the presence of Cave Spiders beneath the church. I chose autumn for my visit in the hope of finding female Bournet's Cave Spiders guarding their egg-sacs. Thankfully the timing was perfect and I wasn't disappointed. On this visit I was able to record 5 adult male specimens, 11 adult female specimens, and 1 sub-adult specimen. I counted a total of 14 egg-sacs, however, only 5 of these egg-sacs had females guarding them so at least some of the others may have been old egg-sacs. The large, white egg-sacs were suspended from the top of the damp walls and had a diameter of around 20-25mm, each resembling small, hairy table-tennis balls. Two of the adult females were in very close proximity with male specimens, which were likely to be their mating partners or potential suitors.
Due to their largely sedentary nature these spiders typically remained fairly motionless even when exposed to the dimmed light of my studio photography lamp, or even the very bright light from my diffused camera flash unit. Some of the females guarding their egg-sacs began to nervously scuttle around the egg-sac as I approached closely with my camera. One female specimen hid behind her egg-sac when my lens got too close. Using a twig I gently lifted the egg-sac to reveal the hiding spider. To my utter surprise the spider then jumped from the egg-sac and landed on my camera, before slipping off and falling to the ground, about 20 inches below. The spider then walked back to the wall, where its egg-sac was suspended, and slowly began to ascend the wall towards the egg-sac once again. However, the spider never actually returned to the egg-sac whilst I was there watching. It's still not clear whether the spider's jump towards my camera was an attempt to flee or maybe to defend the egg-sac?
I was keen to photograph an adult female specimen on a white background so I chose to capture a lone specimen, that was easily accessible, and wasn't guarding an egg-sac, or partnered with a male. The large female specimen I selected didn't have a particularly swollen abdomen, so either it hadn't mated yet, or it had already produced an egg-sac that it wasn't guarding. As I placed the spider on my white sheet of plastic it was noticeably uncomfortable as its legs failed to grip to the slippery surface. It took a few minutes of escape attempts before the spider finally settled down and remained motionless for a brief moment. This pause allowed me the opportunity to capture my photos. During its escape attempts I used my hand to block its escape routes several times, and at no time did the spider exhibit any defensive behaviour other than to run away. After a few minutes I'd captured the images that I was after, and the spider was placed gently back to the exact same spot on the low ceiling where it was found. Once back in place the spider continued to remain motionless, exactly as it was before its capture.
The tiny furnace chamber of St Denis' Church has probably reached its maximum carrying capacity for this species. Although adult Cave Spiders are photophobic, and choose habitats of total darkness, the newly emerged spiderlings are attracted to light and the majority of these will leave the furnace chamber and head off in search of new territories to colonise. One adult specimen has been found under a manhole cover at a nearby residential property, so these spiders can be found in suitable locations in the area that surrounds the church. The only sub-adult specimen that was found on my visit to the church's furnace chamber had built its web on the archway leading into the chamber, and was the closest specimen to the exiting door.
Within the webs of the Cave Spiders I found the remains of Cellar Spiders, Pholcus phalangioides, as well as a small slug, several woodlice and one Violet Ground Beetle, Carabus violaceus. Their were also mosquitoes on the walls that would provide a light meal for the spiders given the chance. The Cave Spiders are not the only predators living under the church. The furnace chamber is also shared with Cellar Spiders, Pholcus phalangioides, that were slightly more numerous than the Meta bourneti. 19 Pholcus phalangioides specimens were recorded on my visit. Pholcus phalangioides are known spider hunters, and whilst I found evidence that Meta bourneti were feeding on young Pholcus phalangioides, it is highly likely that this is reciprocated with Pholcus phalangioides feeding on the young Meta bourneti too.
* Grateful thanks to Peter Mann for allowing me the opportunity to photograph these Meta Bourneti, and thanks to Rob Mungovan for information on the history of this colony. *
13mm male Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
In 2017 - 2018 extensive studies were carried out in Italy, on the ecology of Meta bourneti, by Senior Research Scientist, Enrico Lunghi. By studying numerous caves, on small islands in Sardinia, Lunghi made some interesting observations. It was shown that like Meta menardi, Meta bourneti not only require habitats with near total darkness, but they also require a microclimate with fairly high humidity as well. It was also revealed that Meta bourneti can be found at lower heights on the cave walls during the hotter months of the year, despite the minimal fluctuation in temperature and climatic conditions within the depths of the caves throughout the year. This may be an indicator of just how specific the climate requirements are for Cave Spiders. The deeper one ventures into a cave the more stable the microclimate is. It comes as no surprise that more mature Meta bourneti are usually found deeper within caves, up to around 12 metres from the entrance, and younger specimens can usually be found nearer the cave exit, where climatic conditions show greater variation in line with external changes to the climate outside of the cave. When compared to Meta menardi it seems that Meta bourneti can tolerate environments with a slightly higher variation in temperature. Meta bourneti may also prefer caves with a slightly higher ceiling. On average Meta menardi also appear to favour European sites at a slightly higher elevation to those of Meta bourneti. This may have just been an adaptation to reduce competition for prey between the two similar species.
Although widespread throughout caves in Italy the population density of Meta bourneti was fairly low, with only one Meta bourneti specimen typically being found in each 3 metre section of caves where this species was present. In England the population density within the old furnace chamber at St Denis' Church is extremely high when compared to long established colonies of Meta bourneti found in the Italian caves. It makes one question whether this is down to the abundance of prey availability within the chamber, or if the spiders remain in such close proximity to each other, in the confines of the chamber, because of the lack of alternative suitable habitat in the local area outside of the church? Despite the "nationally scarce" status of Meta bourneti there are actually more records of Meta bourneti in Cambridgeshire than there are for the far more common European Cave Spider Meta menardi.
13mm male Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
13mm male Meta bourneti with a leg-span of 70mm. 9th September 2022.
13mm male Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult male Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult male Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult female Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
The shrivelled abdomen seen on this adult female Meta bourneti is the result of the female having recently produced an egg-sac.
Adult female Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult female Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult female Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult female Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
15mm female Meta bourneti guarding her egg-sac, 9th September 2022.
15mm female Meta bourneti guarding her egg-sac, 9th September 2022.
15mm female Meta bourneti guarding her egg-sac, 9th September 2022.
14mm female Meta bourneti guarding her egg-sac, 9th September 2022.
15mm female Meta bourneti guarding her egg-sac, 9th September 2022
15mm female Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult female Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult female Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Adult female Meta bourneti guarding her egg-sac, 9th September 2022.
7-8mm sub-adult Meta bourneti, photographed at St Denis Church, Cambridgeshire, 9th September 2022.
Cavity Spider / Comb-footed Cellar Spider - (Nesticus cellulanus)
Another species of spider that can also be found in caves, tunnels and other permanently dark habitats is Nesticus cellulanus, also known as the Cavity Spider or Comb-footed Cellar Spider. As a comb-footed spider Nesticus cellulanus builds a small tangle-web or scaffold web. Adult males typically reach 3-5mm and adult females reach 3.5-6mm. Nesticus cellulanus has a pale yellow / orange legs, that sometimes exhibit dark annulations. The carapace is the same colour as the legs, and has a dark, central median band that narrows towards the middle. The carapace is bordered with thin, dark marginal lines. The light coloured abdomen often shows three of four dark rings to both sides of an irregular median band. Darker habitats are usually associated with specimens exhibiting lighter markings.
Adult female specimens can be found all year round but mature males are most commonly seen from March to November. Mating occurs in early summer and between June to August adult females can often be seen carrying a partially translucent pale egg-sac behind them, attached to their spinnerets. Nesticus cellulanus is widespread across the UK but is not often encountered due to its preference for totally dark habitats. Nesticus cellulanus is one of just two identical British species from the Nesticidae family, with Kryptonesticus eremita being the second. Whilst Nesticus cellulanus is common and widespread Kryptonesticus eremita is extremely rare and is confined to just one site in the UK, in Bristol.
The Cave Spider photographs on this page were taken using:
Canon 7D mk I & mk II cameras, Canon 100mm f/2.8L IS Macro lens, Canon 580ex flash, with MK Diffuser.