Meet the spiders in your house with Travis McEnery!

Posted on June 19, 2023 by cataranea

Have you ever found a spider in your home and wondered whether or not you should evict it? If you are a dedicated arachnophile, perhaps you peacefully coexist with spiders no matter their size or habits. But not all spider housemates are equally polite, and you may want to be a little more selective about which spiders you accept as tenants. Some important considerations include the following: Will they make messy cobwebs and leave prey remains around the place, or are they tidy and discreet? Do they hang out in their webs all day, or move around the house, popping up in unexpected places to startle you with erratic movements? And is there any risk of the spiders defending themselves by biting human, feline, or canine members of the household?

The answers these questions (and many more) can be found in the outstanding new youtube series The Spiders in Your House created by “amateur” arachnologist Travis McEnery. This post is an introduction to the series and Travis. I am a huge fan of both, and you should be too!

One of Travis’ first videos, focused on the Common House Spider (Parasteatoda tepidariorum).

These videos are deeply researched, thoughtful, and often hilarious profiles of spiders that you can probably find in or around your own house. I am continually impressed by Travis’ ability to get to the bottom of questions about the spiders he covers. I put “amateur” in scare quotes above when describing him because Travis’ approach to arachnology and the videos he creates is anything but. As a professional arachnologist myself I have learned something new in almost every video (like what was really behind that Mazda recall blamed on yellow sac spiders!), and Travis is directly contributing to spider science through original observations and experiments (he is the creator of my new favourite experimental method for assessing spider biteyness: the cheese test).

Hit play on this video to see the cheese test in action, but definitely also go back to the beginning and watch the whole thing! This episode on yellow sac spiders is just fantastic.

Through his videos, Travis is breaking down barriers between lay people, casual arachnofiles, and professional arachnologists by not only presenting information from the scientific literature in a fun and accessible way, but also by going directly to the scientists behind the studies to get additional context on their findings and sharing what they have to say with the audience. Also, the theme song absolutely s laps.

Click play to hear the theme song.

Another reason I love Travis’ work on this series is that he is constantly learning and sharing that process with the audience. When a fellow arachnologist pointed out a small mistake in one of his videos (on the false widow spiders), he made a whole new video correcting it and in the process shone a light on the messiness of science (we all make mistakes, all the time, and learning from them is a big part of science!) and the value of open communication, collaboration, and a supportive community. This ended up being one of my favourites!

The video correcting a mistake in the episode on false widow spiders.

Head over to Travis’ youtube channel for more excellent videos, consider subscribing, and let him know what you think in the comments! He is super responsive to questions and suggestions, and I am sure you will enjoy learning from him as much as I do! You can also support him and find even more content on his Patreon.

For a bit more information on Travis and his motivation for the series, here’s a piece in The Globe and Mail in which I also appear (talking about the spread of misinformation about spiders). I often lament the lack of factual information about spiders on the internet, and I am extremely happy to see Travis contributing such excellent content and the overwhelmingly positive response to it.

Spider sex and silk: From mating threads and bridal veils to nuptial gifts and silk-lined chambers

Posted on July 13, 2018 by cataranea

I am very pleased to announce the publication of a review paper in the Journal of Arachnology (check out the full pdf here) about the fascinating uses of silk during spider sexual interactions coauthored with Alissa Anderson and my supervisor Maydianne Andrade. This paper has been several years in the making, and some of my very first blog posts were based on the research I did when I first started writing it back in 2013 as part of a reading course for my MSc degree.

Pisaurina mira (a nursery web spider in the family Pisauridae), one of the many diverse species featured in our paper, and the focus of my coauthor Alissa’s PhD research (photo: Sean McCann).

Overview

In this paper we describe the many weird and wonderful ways that male spiders use silk during courtship and mating. Little experimental work has been done to determine the function male silk in sexual interactions, but the available research suggests that in general silk use improves the male’s chances of mating with a particular female or reducing the risk that she will mate with other males. There is also mounting evidence that silk-bound sex pheromones are commonly produced by male spiders (though much less well studied than female silk pheromones), which may help to explain the importance of silk production during sexual interactions in many species. In the paper, we divide male silk use into three categories, briefly summarized below.

Silk deposition on the female’s web or other silk structures

Figure 2 from the paper. Examples of silk deposition onto females’ webs during courtship. (a) Araneus diadematus (Araneidae) male and female hanging from the male’s mating thread, attached to the periphery of the female’s web (photo: Maria Hiles). (b) Web reduction with silk addition by a Latrodectus hesperus (Theridiidae) male. The male has dismantled part of the capture web (which would have filled the lower half of the photograph before he began web reduction behavior) and is wrapping it with his own silk (photo: Sean McCann).

The most common and widespread form of silk use during sexual interactions across spiders is simply the deposition of silk on the female’s web or the silk surrounding her burrow entrance. More elaborate use of silk includes the installation of silk mating threads or webs on which courtship and copulation take place and web reduction, which can result in extreme modification of web architecture. The few experimental studies of this kind of silk use indicate that it is involved with preventing females from mating with other males, as in black widows. However, it is likely that mating threads and webs generally function to improve male mating success by improving transmission of their vibratory courtship signals and/or to reduce the likelihood of sexual cannibalism.

Silk bondage: the bridal veil

Figure 3 from the paper. Examples of silk ‘bridal veils’ applied to females’ legs and bodies during courtship. (a) Nephila pilipes (Araneidae) male depositing silk onto the female’s carapace, legs, and abdomen (photo: Shichang Zhang). (b) Xysticus cristatus (Thomisidae) female with silk on her forelegs and abdomen as she feeds on a prey item—note that the male is underneath her abdomen (photo: Ed Niewenhuys). (c) Latrodectus hesperus (‘‘texanus’’ morph, formerly Latrodectus mactans texanus; Theridiidae) male depositing silk onto the female’s legs (photo: Sean McCann). (d) Pisaurina mira (Pisauridae) male wrapping a female’s legs with silk prior to sperm transfer (Photo: Alissa Anderson).

The “bridal veil” (which I’ve previously written about in detail here) describes the silk some male spiders wrap around females prior to copulation. Arachnologists have debated the function of this behaviour for many years but it has been generally assumed to prevent sexual cannibalism. In some species like the nursery web spider Pisaurina mira, the silk wrapping physically restrains the female, giving the male time to escape while she struggles free of her bonds. In the orb-weaver Nephila pilipes, on the other hand, tactile cues and chemicals on the silk have been implicated in reducing the female’s aggressive tendencies. In both species, males that wrap females with silk are able to transfer more sperm to females, improving their mating success. Bridal veils are used by males from at least 13 families of spiders, including both web builders and wanderers, and there is still much to learn about the function of this fascinating behaviour across the diverse species that use it. In one species of wolf spider, the female even eats the silk of the veil after mating, which brings us to the third category of male silk use.

Silk wrapped nuptial gifts, or the gift of silk itself

Figure 4 from the paper. Examples of silk-wrapped nuptial gifts. (a) Female (right) Pisaura mirabilis (Pisauridae) accepts a silk-wrapped gift from a male (photo: Alan Lau). (b) A male (right) Metellina segmentata (Tetragnathidae) has wrapped a rival male in silk as a nuptial gift for the female (photo: Conall McCaughey).

In two families of spider, the nursery web spiders (Pisauridae) and their close relatives the longlegged water spiders (Trechaleidae) males present females with silk wrapped prey items called nuptial gifts (which I previously wrote about here). Sometimes, though, the silk package actually contains non-food items like rocks or plant material. The silk itself seems to be the important thing for getting the female to accept the gift and grasp it in her jaws, keeping her busy (and the male safe) during copulation. Both visual signals associated with the colour of the silk and chemicals on the silk may be important ways that gift-giving males communicate their quality and persuade females to mate with them, not to mention potentially deceiving them into accepting worthless gifts.

In other spiders gift-giving is less ritualized or happens only some of the time, like in the longjawed orbweaver Metellina segmentata. Males of this species often compete on the female’s web, and sometimes one of them will kill his rival, wrap him up with silk, and present him to the female. As with the habitual gift-givers discussed above, mating with the female while she is busy feeding on her erstwhile suitor likely decreases the male’s chance of becoming dinner. In still other spiders, the silk itself constitutes the gift, rather than the wrapping. In the ray spider Theridiosoma gemmosum, the male feeds the female silk directly from his spinnerets during courtship and copulation. This silk gift provides the female with nutrients (these spiders can recycle silk proteins). Finally, silk-lined burrows are considered gifts in the sex-role reversed wolf spiders Allocosa senex and A. alticeps. In these species, males dig deep silk-lined burrows to which they attract females with a pheromone. Mating takes place inside the burrow, and afterward the male helps the female to seal herself inside the burrow where she lays and broods her egg sac. The energy and silk that go into producing the burrow are a considerable investment for the male, and directly benefit the female and his offspring by providing a safe refuge.

The big picture

Silk use during courtship occurs in diverse species all across the spider tree of life, and provides myriad opportunities for future research. In the figure below, many families are not highlighted, but this is as likely to represent lack of knowledge about their courtship behaviour (or even anything about their natural history) as lack of silk use, and I hope that this paper will inspire other arachnologists to investigate mating behaviour, silk use, and the potential for male pheromone production in some of these little studied spiders. There are undoubtedly many exciting new discoveries to be made and I look forward to reading about them and perhaps making some myself in the future.

Figure 1.—Cladograms illustrating relationships between araneomorph spider families (based on Wheeler et al. 2016) and the occurrence of male silk and pheromone use. Note that in the Mygalomorphae (families not shown on the figure) there are records of male silk deposition on the female’s web or silk for species in the following three families: Dipluridae, Porrhothelidae, and Theraphosidae.

Full citation of the paper:

Scott CE, Anderson AG & Andrade MCB. 2018. A review of the mechanisms and functional roles of male silk use in spider courtship and mating. Journal of Arachnology 46(2): 173-206. Open access here

Fishing spiders (family Pisauridae)

Posted on June 20, 2016 by cataranea

Today’s featured spiders for Spider Week are the fishing spiders (also known as raft spiders) in the genus Dolomedes. I suspect the reason they are so often mistaken for brown recluse spiders is that they are (a) brown, and (b) often very large. Brown recluse spiders aren’t particularly large, but folks seem to (erroneously) associate size with danger when it comes to spiders.

A large female Dolomedes tenebrosus from southern Ontario. Photo: Sean McCann, used with permission.

Fishing spiders are members of the family Pisauridae, commonly known as nursery web spiders. Female spiders in this family make excellent mothers. They carry their large silken egg sacs around in their chelicerae (jaws) until the spiderlings inside are just about ready to emerge. Presumably this means that females don’t eat at all during this time!

Dolomedes female carrying her egg sac in her jaws. Photo: Ron Knopik, licensed under CC BY 2.0.

The spider then builds a nursery web in vegetation and suspends the egg sac inside. She stands guard until the spiderlings emerge. They remain in the nursery web for a while, undergoing one moult before setting out on their own.

Nursery web spider guarding her nursery in New Zealand. Photo: Tony Wills, licensed under CC BY 3.0.

The large fishing spiders, including Dolomedes tenebrosus and Dolomedes scriptus are also sometimes called dock spiders or wharf spiders. They are typically found on or near water – often on human-made structures.

Dock spider (Dolomedes tenebrosus) on part of a wooden wharf in Ontario. Photo: Sean McCann, used with permission.

As their common name suggests, fishing spiders make a living hunting for fish, tadpoles, and aquatic invertebrates. They can walk on water and even sail across the water’s surface either by lifting their front legs, or by standing up on ‘tip-toe’ to catch the wind.

Six-spotted fishing spider (Dolomedes triton)resting on the surface of a pond in the Okanagan. Photo: Sean McCann, used with permission.

While hunting, fishing spiders typically rest with their back legs on floating wood or vegetation, and their front legs resting lightly on the water’s surface. This way they can detect surface waves on the water, allowing them to locate potential prey. If the spider detects a fish under the water, they use their back legs to push off and dive after it. Dolomedes triton also dives under water when disturbed – this may be a good way to avoid predators such as birds (or a scary human trying to catch them, which is how I first observed this behaviour). And they can stay under water for up to half an hour! They are able to breathe underwater because spider lungs are located on the abdomen, which is covered with fine hairs that trap air, forming a sort of diving bell.

Fishing spider (Dolomedes tenebrosus) in hunting position on the water’s surface. Photo: Sean McCann, used with permission.

Notes on Identification

Fishing spiders are most likely to be confused with wolf spiders (family Lycosidae). The best way to tell them apart is the eye arrangement. Wolf spiders have three rows of eyes, with the forward-facing pair in the middle row (the posterior median eyes) very large, and the first row of four eyes in a straight line or slightly procurved (curved downwards).

Wolf spider eye arrangement. Photo: Sean McCann, used with permission.

Fishing spiders have only two rows of four eyes each. Both rows are slightly recurved (curving upwards or toward the back end of the spider) and the posterior median eyes are not that much larger than the rest.

Fishing spider eye arrangement. Photo: Sean McCann, used with permission.

References and further reading:

A dedicated mother (with fantastic photos!) by Alex Hyde

Canada’s largest spider by Chris Buddle

Pisauridae: Nursery web spiders by Africa Gomez

Adams, R. J. (2014). Field Guide to the Spiders of California and the Pacific Coast States (Vol. 108). University of California Press.

Bradley, R. A. (2012). Common Spiders of North America. University of California Press.

Carico, J. E. (1973). The Nearctic species of the genus Dolomedes (Araneae: Pisauridae). Bulletin of The Museum of Comparative Zoology, 144:435-488.

McAlister, W. H. (1960). The diving and surface-walking behaviour of Dolomedes triton sexpunctatus (Araneida: Pisauridae). Animal Behaviour,8(1-2), 109-111.

Nyffeler, M., & Pusey, B. J. (2014). Fish predation by semi-aquatic spiders: a global pattern. PLOS ONE, 9(6), e99459.

Suter, R. B. (1999). Cheap transport for fishing spiders (Araneae, Pisauridae): The physics of sailing on the water surface. Journal of Arachnology, 27:489-496.

Yellow sac spiders (family Cheiracanthiidae)

Posted on June 19, 2016 by cataranea

Note: this post has been updated to reflect that the yellow sac spiders are now in the family Cheiracanthiidae. At the time of first writing, they were in the family Eutichuridae.

The first spider of spider week, squeezing into the 7th-most-likely-to-be-misidentified-as-a-brown-recluse spot (despite not even being brown), is the yellow sac spider. This common name may be used to refer to multiple similar-looking species in the genus Cheiracanthium (family Cheiracanthiidae).

Cheiracanthium inclusum (female). Photo: Joe Lapp (also known as Spider Joe), used with permission.

In North America we have two species: Cheiracanthium inclusum (a native species) and C. mildei (introduced from Europe). Other names for yellow sac spiders include black-footed spiders, long-legged sac spiders, and yellow house spiders. All are pretty good descriptive names, because Cheiracanthium are indeed long-legged, black-footed, and commonly found in houses. Cheiracanthium mildei is more often found indoors, whereas C. inclusum (also known as the agrarian sac spider) is more common outdoors in fields and foliage.

Cheiracanthium male. Photo: Sean McCann, used with permission.

Identification: Yellow sac spiders are fairly easy to identify based on some distinctive features. They have relatively long legs, with the front pair of legs longer than the rest, and black “feet” (tarsi equipped with tufts of dark hairs that allow the spider to easily scale vertical walls). Overall colouration can vary from pale yellow or tan to light green or even sometimes orange or brown, depending on the spider’s diet. Typically there is a darker longitudinal stripe called a heart mark (because that’s where the spider’s heart is) along the abdomen. Although most folks don’t usually get close enough to count them, the eight eyes are all similar in size and arranged in two nearly straight rows. Sac spiders in the family Clubionidae are probably most likely to be confused with yellow sac spiders, but they have shorter, more robust legs, and the front pair is not longest.

Cheiracanthium inclusum. Photo: Joe Lapp, used with permission.

Cheiracanthium eye arrangement. Photo: Don Loarie, licensed under CC BY 2.0.

Cheiracanthium male. Photo: Natalie McNear, licensed under CC BY-NC 2.0.

Natural History: Yellow sac spiders build silk ‘sleep-sacs’ in rolled up leaves (when living in the great outdoors) or where walls meet ceilings inside houses. They may rebuild these retreats every night just before dawn, and rest inside during the day.

Yellow sac spiders are active nocturnal hunters, but in addition to insects and other arthropods, they also feed on extrafloral nectaries of plants such as castor bean. Most people think of spiders as strict carnivores, but in practice many spiders have a more varied diet.

When a male finds a female in her sleep sac, they tap on the outside of the silk retreat (how polite!) and then start cutting the silk away from the entrance (less mannerly).

Myth-busting

For a time, Cheiracanthium was considered one of three ‘medically significant’ spider genera in North America, along with the recluse spiders (Loxosceles) and the widow spiders (Latrodectus). Their bad reputation turns out to be undeserved – they do NOT cause necrotic lesions like brown recluse spiders as was once thought. They do have a rather painful bite – like a bee or wasp sting – but the results of envenomation are not serious. Because they often live in close association with humans, bites from these spiders may be more common than spider bites in general, but still extremely rare. (There’s probably one or more in your house, and you’ve almost certainly never been bitten – you’d know it if you had!) Remember that spiders don’t bite humans except in very rare circumstances.

Cheiracanthium sp. from in Illinois. Note that it is NOT biting, but rather trying to escape! Photo by Andrew Hoffman, licensed under CC BY-NC-ND 2.0. Check out his blog post about yellow sac spiders and the taking of this picture.

Another myth holds that these spiders are attracted to the smell of gasoline. Yellow sac spiders were responsible for the recall of several thousand cars but there is no actual evidence that they like the smell of gas.

References

Adams, R. J. (2014). Field Guide to the Spiders of California and the Pacific Coast States (Vol. 108). University of California Press.

Bradley, R. A. (2012). Common Spiders of North America. University of California Press.

Taylor, R. M., & Foster, W. A. (1996). Spider nectarivory. American Entomologist, 42(2), 82-86.

Vetter, R. S., Isbister, G. K., Bush, S. P., & Boutin, L. J. (2006). Verified bites by yellow sac spiders (genus Cheiracanthium) in the United States and Australia: where is the necrosis? The American journal of tropical medicine and hygiene, 74(6), 1043-1048.

More blog posts about yellow sac spiders:

The Ceiling Spider by Chris Buddle

Blame it on the sac spider by Andrew Hoffman

Longlegged sac spiders by Bug Eric

Zora & Syspira: wolf-like prowling spiders

Posted on May 9, 2016 by cataranea

Did you ever come across one of the most beautiful wolf spiders you’ve ever seen, only to realize that it’s not a wolf spider at all, because the eyes are all wrong? And if it’s not a wolf spider then what the heck is it because it doesn’t look like a spider from any of the other spider families you’re familiar with? No? Well, I had this experience recently. Twice, actually.

The first time it happened was during our epic journey from Toronto to southern Texas to California and then to Victoria (also known as #SpiderTrip2016 – check out some of the great photos Sean took along the way here). We stopped one morning in Joshua Tree National Park and flipped over some rocks to see if we could find any insects or spiders hiding underneath. Almost immediately, I uncovered this gorgeous spider with perfect desert camouflage.

Not a wolf spider. Photo: Sean McCann.

The bold markings reminded me a bit of some funnel-web weavers in the family Agelenidae, but this spider didn’t have a web.

Agelenopsis aperta (family Agelenidae, the funnel-web weavers). Yeah, this spider isn’t on a web either, but that’s because we put it on a rock to get a good photograph of it. Agelenids are usually pretty camera-shy, and they like to hide in their retreats. Photo: Sean McCann.

The sandy camouflage was similar to that of the beach-dwelling wolf spider Arctosa perita, but on closer inspection I realized the eyes were all wrong for it to be a lycosid.

Arctosa perita, with characteristic wolf spider eye arrangement. Photo: Sean McCann.

The key to figuring out whether or not you’ve got a wolf spider is the eye arrangement. Lycosids are visual hunters that have their eyes arranged in three rows. The first row has four small eyes, the second has two large forward-facing eyes, and the third has another pair of slightly smaller eyes quite far back on the cephalothorax. From straight on, they may appear to have only 6 eyes (the first two rows).

Wolf spider (family Lycosidae) eye arrangement. Photo: Sean McCann.

Syspira is clearly not a wolf spider – it has two rows of four eyes (or if you like, a smiley face eye arrangement – once you see it, you won’t be able to un-see it!) that are all pretty similar in size.

From above, the eyes appear to be arranged in two more or less straight rows.

I never would have guessed by looking at it that this spider is in fact a prowling spider in the family Miturgidae. When I think of miturgids, the first thing that comes to mind are the long-legged sac spiders in the genus Cheiracanthium.

Cheiracanthium sp. – a yellow sac spider in the family Eutichuridae (formerly placed in Miturgidae, and before that, Clubionidae – spider systematics is complicated and constantly changing). Photo: Sean McCann.

These “yellow sac spiders” are famous for being common in homes, biting people all the time (actually, they rarely bite) and causing necrosis (they don’t, although bites are painful like a bee sting), and causing car trouble. They also aren’t actually in the family Miturgidae. They used to be, but they recently got separated into a new family called Eutichuridae, so I really need to update my mental inventory of spider families! Anyway, because the spider we found didn’t look at all like a long-legged sac spider, I didn’t think of looking in the family Miturgidae. It was only later that I was browsing Marshal Hedin’s wonderful collection of spider photographs on entirely unrelated business that I came across this photograph:

Immature Syspira sp. (family Miturgidae, also known as the prowling spiders). Photo: Marshal Hedin. Licensed under CC BY-SA 2.0.

That’s it! That’s our spider! Not only does it look pretty much identical, but it was found in the very same desert where we found ours. Syspira! The trail goes cold here, however. I can’t say for sure what species it is because the most recent revision of the genus is an unpublished thesis that I can’t get my hands on at the moment (for what it’s worth, I suspect Syspira tigrina). And very little is known about the natural history of these spiders. They are nocturnal wandering hunters who hunker down under rocks or other objects during the heat of the day. They are a pretty good size – the body length (combined length of the two body segments) of the individual we found is probably about 15 mm.

Female Syspira sp. Photo: Sean McCann.

Our second wolf-like spider is a much smaller critter (less than 5 mm in body length) that we found wandering the forest floor while we were hiking at Mount Work on southern Vancouver Island this past weekend.

Wolf-like spider from Mount Work. Photo: Sean McCann.

This photo shows how tiny this spider is relative to Sean’s thumbnail. Photo: Sean McCann.

This little guy definitely had us thinking he was a wolf spider until we took a closer look at his eyes. The eye pattern is sort of similar to that of a lycosid, but I only see two rows of four eyes rather than three distinct rows, and the middle two eyes in the second row (called the posterior median eyes if you want to be technical) are too close together. This eye arrangement is more similar to that of ctenids (wandering spiders, which we don’t have in Canada) or pisaurids (nursery web spiders and fishing spiders).

Eye arrangement of our mystery spider. Photo: Sean McCann.

I guessed that this might be Zora hespera (another miturgid!) based on a drawing of a similar tiny spider in our field guide, and our friend and arachnological guru Robb Bennett quickly confirmed the guess. As it turns out, this species was only described in 1991, and Robb first documented its presence in British Columbia in 1996.

Adult male Zora hespera (Miturgidae). Photo: Sean McCann.

The genus Zora used to be in the family Zoridae, which no longer exists (if you use the excellent Field Guide to the Spiders of California, however, you’ll still find Zora hespera listed as a zorid). The name Zora is also new – the genus was originally called Lycaena (which means female wolf) because of its similarity to wolf spiders, but the name had to be replaced because it was already being used for a butterfly genus. These spiders hunt on the ground and low vegetation during the day and are most often found in open sunny areas of wooded or disturbed habitats.

Adult male Zora hespera. Note how small he is relative to the pine needles! He was pretty cryptic against the forest floor. Photo: Sean McCann.

The individual we found prowling the forest floor is a male (you can tell by the enlarged pedipalps) who may have been on the hunt for a female. Courtship in this species is brief and includes a leg-waving display on the part of the male. Once mated, the female produces an egg sac that she attaches to the underside of a rock or other object. A flat sheet of silk hides the egg sac and the female stands guard to protect her offspring from predators and parasites.

Syspira sp. looking cryptic on the desert sand. Photo: Sean McCann.

Spider identification can be tricky! Next time you think you’ve found a wolf spider, take a closer look – it might be a wolf-like prowling spider, or something else altogether! The more time I spend learning about spiders, the more amazed I am by their beauty and diversity.

References

Adams, R. J. (2014). Field Guide to the Spiders of California and the Pacific Coast States (Vol. 108). University of California Press.

Bennett, R. G., & Brumwell, L. J. (1996). Zora hespera in British Columbia: a new spider family record for Canada (Araneae: Zoridae). Journal of the Entomological Society of British Columbia, 93, 105-110. PDF

Bradley, R. A. (2012). Common Spiders of North America. University of California Press.

Corey, D. T., & Mott, D. J. (1991). A revision of the genus Zora (Araneae, Zoridae) in North America. Journal of Arachnology, 55-61. PDF

Ubick, D., Paquin, P., Cushing, P., & Roth, V. (2005). Spiders of North America – an identification manual. American Arachnological Society.

Rhomphaea: ridiculously long theridiids

Posted on April 23, 2016 by cataranea

Male Rhomphaea fictilium – a theridiid with a ridiculously long abdomen and pedipalps! Photo: Al Denesbeck (used with permission).

I’ve written about long spiders before: the “stretch spiders” in the family Tetragnathidae (long-jawed orb-weavers) are notable for their elongated bodies as well as their long jaws. When I first spotted Rhomphaea, I thought it might be a tetragnathid, before taking a closer look and realizing it must be something else entirely. As it turns out, Rhomphaea is a very odd-looking member of the family Theridiidae, or comb-footed spiders, which includes the black widows!

Rhomphaea fictilium from my field site at Island View Beach on Vancouver Island, BC. This spider does not show much resemblance to its relatives the black widows, who are found nearby! Photo: Sean McCann (used with permission).

Rhomphaea is a Latin word of Thracian origin that literally means long spear or javelin. The long, straight abdomen of the male in the photo below helps explain the name.

Male Rhomphaea fictilium with long, “spear-like” abdomen and extremely long pedipalps. Photo: Kyron Basu, licensed under CC BY-ND-NC 1.0.

Below is a female Rhomphaea projiciens with her egg sac. Note that the spider has a tiny spine on the end of her abdomen, making it more literally spear-like!

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Rhomphaea prociciens female with egg sac. Photo: Jon Hart (used with permission).

My first encounter with this genus was observing Rhomphaea fictilium. Fictilis means “clay” in Latin, and the Latin-derived English adjective fictile “means capable of being molded.” The abdomens of Rhomphaea fictilium are worm-like and flexible, allowing the spider to change its shape. This ability may help Rhomphaea to camouflage itself in different contexts – the shortened abdomen of the little one in the photo above helps it to blend in with the seed heads it rests on. When their abdomens are held out long and straight, these spiders can look like very convincing sticks. The incredible photo below shows an individual that looks like it has the tail of a (very tiny) dragon!

Rhomphaea fictilium with extended abdomen (dragon’s tail?). Photo: Gergin Blagoev, licensed under CC BY 3.0.

As well as having wonderfully strange morphology, Rhomphaea have rather unusual habits. Most spiders are generalist predators, and spiders in the family Theridiidae typically build tangle webs that they use to catch crawling insects and other arthropods, including other spiders. Rhomphaea, unlike most of their relatives, specialize on hunting other spiders. They do sometimes build their own rudimentary webs from just a few silk lines, but they also enter the webs of other spiders and use aggressive mimicry to hunt their owners. Rhomphaea will pluck the web and produce vibrations that lure the resident spider out to investigate what they perceive to be prey caught in the web. The web-building hunter then becomes the hunted, tricked into the approaching the dangerous intruder. Rhomphaea fictilium have been reported to prey on other theridiids, orb-weavers (araneids), sheet-weavers (linyphiids) and others.

Rhomphaea fictilium with its unfortunate prey. Note that the spider is covered with silk – theridiids comb sticky silk out of their spinnerets with their fourth legs and throw it over their victims to subdue then before biting. Photo: Al Denesdbeck (used with permission).

These tiny, cryptic spiders are rare and difficult to spot, but keep your eyes out for them in low tree branches, grasses, and bushes – or in the webs of other spiders!

References & further reading

Bradley, R. A. (2012). Common Spiders of North America. Univ of California Press.

Exline, H., & Levi, H. W. (1962). American spiders of the genus Argyrodes (Araneae, Theridiidae). Arañas americanas del género Argyrodes (Araneae, Theridiidae). Bulletin of the Museum of Comparative Zoology., 127(2), 75-202. Full text at BHL

Paquin, P., & Dupérré, N. (2001). On the distribution and phenology of Argyrodes fictilium (Araneae, Theridiidae) at its northern limit of North America. Journal of Arachnology, 29(2), 238-243. PDF

Oecobiidae

Posted on December 6, 2015 by cataranea

Last week a colleague of mine found a tiny spider we didn’t recognize in the biology building at UTSC. We regularly find common house-dwelling spiders in and around the buildings on campus (most often false widows, Steatoda ~~grossa~~ triangulosa). But this spider was different from the ones we usually find in the building – tiny (only a couple of millimetres long), pale in colour, and a very fast runner! I brought it home and asked Sean to take some photos of it, and we soon realized it was a member of the fascinating family Oecobiidae. [note: this paragraph was revised on 7 Dec. 2015]

Oecobius sp. from Scarborough, Ontario. Photo: Sean McCann (used with permission)

The name Oecobiidae comes from the Greek words oikos (οικος), meaning “house” and bios (βιος), meaning “living”. A name that means “living in the house” is highly appropriate for these synanthropic spiders that are commonly found in human dwellings. The spider we found is most likely one of two species that have a worldwide distribution and can be found in southeastern Canada: Oecobius cellariorium (cellariorium means, unsurprisingly, “of the cellar” in Latin) and Oecobius navus (navus means active or busy, which these little spiders certainly are!).

Oecobiid next to its sheetweb. Photo: Mark Yokoyama, licensed under CC BY-NC-ND 2.0

Despite their very appropriate scientific names, non-Latin and Greek speakers have come up with a variety of fun common names for members of this family. These include wall spiders, baseboard spiders, stucco spiders, starlegged spiders, disc web spiders, and dwarf round-headed spiders. The official common name for the family is “flatmesh weavers” (at least in North America, according to the American Arachnological Society) because of the flat webs they build.

Figures 2 and 3 from Glatz 1969, showing the two kinds of webs built by Oecobius navus (previously called Oecobius annulipes). The first is a “star-shaped” web with an upper and lower sheet surrounded by radiating silk lines. These threads allow the spider sitting on the lower sheet to detect vibrations produced by prey. When the spider detects prey outside its web it can rush out in any direction to capture it. The second type of web is similar, but the upper and lower sheets form a tube, with only two entrances.

I quite like the name starlegged spiders for oecobiids though, because it so aptly describes one of the very distinctive characteristics of spiders in this family. Unlike most spiders, which have the first two pairs of legs pointing forward and the last two pointing backward (an exception is the family Segestriidae, which have the first three pairs pointing forward), oecobiids have all 8 legs sticking more or less straight out from their bodies, in a somewhat starburst-like fashion.

Oecobius sp. (male). In addition to being “star-legged”, oecobiids have their 8 eyes arranged in a characteristic cluster in the centre of a circular cephalothorax. Photo: Sean McCann

The defining characteristic of oecobiids, however, is the extraordinary anal tubercle (that’s exactly how it’s described in this paper, and I assure you it is entirely appropriate). Seriously, these tiny spiders have the most incredible hairy butts! Ahem. Fringed anal tubercles, I mean. Let me explain.

The North American oecobiids are cribellate spiders. What this means is that the spider is equipped with a cribellum (a special silk spinning organ covered with thousands of tiny spigots) near the spinnerets and a calamistrum (a specialized row of bristles) on each of the fourth legs. The calamistrum is used to comb out fine strands of cribellar silk into sheets with a fuzzy texture. The stickiness of this silk comes from its physical structure, as opposed to the glue used by ecribellate (non-cribellate) spiders to make their capture silk sticky. Anyway, instead of combing silk out of the cribellum with the calamistrum like regular cribellate spiders, oecobiids have their own fancy way of doing things. They use the fringe of hairs on their jointed anal tubercles to comb silk directly from arrays of spigots on a pair of enlarged spinnerets.

Figure 11 from Glatz 1969, showing the extraordinary fringed anal tubercle and spinning apparatus. The long posterior lateral spinnerets (labelled hspw) are covered with spigots (s). The outer fringe of hairs (rh) on the anal tubercle comb silk out of the spinnerets. The anal tubercle is also equipped with sensory hairs (mh) that are used to detect prey movement via vibrations through the silk threads.

This unusual set-up enables oecobiids to produce a sheet of sticky silk without using their legs, which is important for their unusual method of prey capture. Many spiders use their last pair of legs to pull sticky silk out of their spinnerets and throw it onto their prey. Oecobiids, instead, run around and around their prey in circles as they spew out ribbons of silk from their feathery butts. Once the victim (often an ant) is fully encircled and stuck to the substrate, the spider bites it. Here is a video of the behaviour. (Video* by Ahmet Özkan, used with permission.)

As you can see in the video, the spider does occasionally use its last pair of legs while wrapping the ant with silk, but the anal tubercle/spinneret combo does most of the work. Female and juveniles of Oecobius navus can produce cribellar silk, but adult males have a reduced cribellum and don’t have a calamistrum at all. Another oecobiid genus, Uroctea, used to be placed in its own family, the Urocteidae, because they are ecribellate (lacking the cribellum and calamistrum).

Uroctea durandi, one of the ecribelleate oecobiids. Photo: Siga, licensed under CC BY-SA 3.0

Early work on spiders in the genus Oecobius suggested that they were ant-specialists, but more recent research has shown that they eat a variety of prey types. However, different populations of a single species seem to specialize to some extent on whatever type of prey is most locally abundant. In Portugal, a population of Oecobius navus preys mainly on ants, but another population in Uruguay eats mostly flies.

Male (right) and female (left) Oecobius sp. Photo: Allan Lance (used with permission). Check out more of Allan’s photos of oecobiids here.

Reproductive behaviour has only been well documented in Oecobius navus. The male spins a tubular silk mating web on top of the female’s retreat and tries to entice her to join him inside. Copulation only occurs if she enters the male’s web, and sometimes the female will cannibalize the male during or after mating. Females are not caring mothers in this species – they spin several egg sacs that each contain only 3 to 10 eggs and then abandon them.

Oecobius sp. from Scarborough. Photo: Sean McCann

Now that you know all about oecobiids, keep your eyes out for them! They live all over the world, and often on the walls and ceilings of houses. You never know – there might be one in the room with you right now!

This photo of an Oecobius sp. is one Sean dug up from his archives. We had found the spider in our old lab at SFU in BC, and did not identify it at the time. When Sean showed me the photo recently, and I started trying to ID it, I took a look at the checklist of BC spiders to get an idea of which species it might be. I didn’t see any oecobiids on the list, so I emailed the author, Robb Bennett, and it turns out that this photo is the first record of the family for British Columbia.

*For another cool oecobiid video with a surprise ending, click here.

References

Adams, R. J. (2014). Field Guide to the Spiders of California and the Pacific Coast States (Vol. 108). Univ of California Press.

Glatz, L. (1967). Zur biologie und morphologie von Oecobius annulipes lucas (Araneae, Oecobiidae). Zeitschrift für Morphologie der Tiere, 61(2), 185-214.

Líznarová, E., Sentenská, L., García, L. F., Pekár, S., & Viera, C. (2013). Local trophic specialisation in a cosmopolitan spider (Araneae). Zoology, 116(1), 20-26.

Shear, W. A. (1970). The spider family Oecobiidae in North America, Mexico, and the West Indies. Harvard Univ Mus Compar Zool Bull.

Myrmecophilic spiders

Posted on November 1, 2015 by cataranea

Myrmeco = ant; philic = loving

Note: All photos in this post are copyright Sean McCann.

Yesterday, for the final day of Arachtober, Sean and I went to Tommy Thompson park in Toronto to look for some autumn arachnids and other arthropods. Sean was very excited when he turned over a rock and found a nest of acrobat ants, Crematogaster cerasi. The genus Crematogaster is mainly tropical, and we didn’t have them back in BC, so it was a pretty cool find for us.

Then we took a closer look at the ants running around under the rock. One of these ants is not like the others!

The interloper is a myrmecophilic spider in the family Phrurolithidae – probably Phruronellus formica. Athough they are not modified to look especially ant-like in shape, their shiny black abdomens certainly help them to blend in with the colony.

Hey look, there’s another one! Although we were almost fooled by the imperfect ant-mimicry of these spiders, ants rely much more on smell and touch than vision, so looking a bit ant-like wouldn’t do much to help them fit in. It may, however, provide some protection against predators that find ants distasteful or difficult to eat.

Not much is known about their natural history, but Phruronellus formica is thought to be an obligate associate of ants in the genus Crematogaster [1,2]. If they are disturbed, they disappear into the ants’ nest. This implies that the spiders are not only not recognized as intruders by the ants, but are tolerated by their hosts. Presumably they produce or acquire compounds that allow them to wander freely among the ants, who recognize their nest-mates by their colony-specific chemical profile.

The relationship between Phruronellus formica and Crematogaster has not been studied, but based on what is known about other spider-ant associations [2,3], we can infer a bit about how this arrangement benefits the spiders. Living amongst ants can provide spiders with a comfortable home, free food, and protection from enemies. Myrmecophilic spiders are known to prey on other ant-associates (like collembolans), prey brought back to the colony by their ant hosts, or even the ants themselves. Ants are also fierce defenders, armed with stings or noxious defensive chemicals to protect the colony (and, incidentally, the spiders within it) from predators.

This doesn’t seem like a very good deal for the ants – at best, the spiders have no effect on them, and at worst, they are stealing food or preying on their hosts or their beneficial symbionts [3]. But the number of spiders in any colony is so small (we saw two among hundreds of ants, in a colony that probably has about 2000 workers) that they are probably not harmful enough to make it worth the ants’ while to do anything about them.

References:

1. Emerton, J. H. 1911. New spiders from New England. Trans. Connecticut Acad. Arts and Sciences 16: 383-407. full text

2. Cushing, P. E. (1997). Myrmecomorphy and myrmecophily in spiders: a review. Florida Entomologist 165-193. PDF

3. Cushing, P. E. (2012). Spider-ant associations: an updated review of myrmecomorphy, myrmecophily, and myrmecophagy in spiders. Psyche: A Journal of Entomology. doi:10.1155/2012/151989

Pirate spiders

Posted on October 26, 2015 by cataranea

Mimetidae are the pirates of the spider world, but their acts of theivery take place on the webs, rather than ships, of other spiders. The name Mimetidae means “imitator” and is thus a very fitting name for these sneaky spiders.

A mimetid found at Payne’s Prairie in Florida. Photo: Sean McCann (used with permission).

Common names for this family include pirate spiders and cannibal spiders, for reasons that will soon become clear. They have a worldwide distribution, occurring on every continent except Antarctica, and everywhere in North America except the arctic.

What makes mimetids so fascinating is their predatory behaviour. These spiders don’t build their own webs. Instead, they invade the webs of other spiders – most often spiders in the families Araneidae (orb-weavers), Theridiidae (cobweb weavers), and Dictynidae (mesh web weavers). Here’s a series of photographs showing an interaction between a pirate spider and an orb-weaver in Arizona. (Full disclosure: Sean and I introduced the mimetid ourselves, hoping to witness a predation event).

Below is the web of a trashline orbweaver, Cyclosa turbinata (family Araneidae). The vertical “trashline” that bisects the upper half of the orb is made of old prey carcasses.

This photo and the rest in this series by Sean McCann.

Here’s a closer look at the trashline. The spider is well camouflaged when she sits right in the centre of the orb-web.

Here’s a better view of the spider herself.

And this is another Cyclosa conica female, for a better idea of what these spiders look like.

Ok, now back to the pirate spider! This is a male Mimetus hesperus that we found nearby, and introduced onto the yucca right next to the orb-web.

Soon he entered the periphery of the web and assumed the ‘legs cocked’ posture characteristic of hunting mimetids. He then started carefully plucking the threads of the orb-web with his front pair of legs. This plucking makes the web vibrate in very much the same way it would if an insect had been captured, and resulted in the Cyclosa female orienting toward the source of the vibrations, but remaining in the hub of the web.

Mimetid_vs_Cyclosa_IMG_5075

Gradually Mimetus began to move toward the hub of the orb-web, plucking and sometimes even snapping spiral threads (much as would happen if a winged insect was struggling to free itself from the sticky threads). At first it seemed the mimetid was going to be successful in luring the female Cyclosa out onto the web and into its deadly embrace, but after a few steps toward the mimetid she suddenly dropped out of the web on a dragline.

As Cyclosa hung below, the mimetid made his way to the hub of the web and took up residence. Sean and I were impressed by Cyclosa’s ability to recognize the mimetid as as being dangerous rather than dinner, but disappointed not to see Mimetus succeed in securing a meal. So we put the spider back onto her web. (Sorry Cyclosa!)

As soon as she started moving back toward the hub, Mimetus lunged and bit Cyclosa. Mimetids are equipped with a spider-specific venom that paralyzes their prey almost instantly.

The successful pirate then carried its meal back to the periphery of the web to feed. Below you can see that he has Cyclosa by the leg. Apparently mimetids almost always bite the legs of their victims, and when they do paralysis occurs within moments. If they bite another spider’s abdomen, however, the venom takes much longer to work.

We left the pirate enjoying his meal on the yucca. He may have gone on to find a new web to invade, or taken over Cyclosa’s web for a while. If we hadn’t interfered, he may have remained in the hub of the web and used it to capture insect prey himself. In addition to this sort of takeover, mimetids are also known to steal prey from the webs of other spiders who are much larger (and thus too big to prey on). They also sometimes eat the eggs of other spiders.

Mimetus sp. from High Park in Toronto, Ontario. Photo: Sean McCann (used with permission).

Notes on identification:

Mimetids look most similar to orb-weavers (araneids) and cobweb weavers (theridiids) but they can be distinguished from spiders in all other families by the unique pattern of spines on their first two pairs of very long legs.

Nice example of the characteristic spination on the tibiae and tarsi (first two leg segments) of the first two legs of pirate spiders. Photo: Nicky Bay (used with permission). Check out more of Nicky’s awesome pirate spider photos here.

The eye arrangement is not so diagnostic (it’s quite similar to that of araneids and theridiids) but here’s a great portrait courtesy of the Insects Unlocked project.

Finally, Mimetids build characteristic egg sacs that are easy to identify to genus even in the absence of the mother (who inevitably abandons her offspring). The sac has a long thin stalk and/or a fluffy coating, depending on the genus, and these two features may help protect the eggs within from parasitoids or predators.

Egg sac of a mimetid in the genus Ero, found hanging inside a hollow stump in Burns Bog, Delta, BC. Photo: Sean McCann (used with permission).

References and further reading:

Eric Eaton’s blog post on pirate spiders.

Africa Gomez’s blog post on pirate spiders.

Bristowe, W. S. (1958). The world of spiders. London: Collins.

Jackson, R. R., & Whitehouse, M. E. (1986). The biology of New Zealand and Queensland pirate spiders (Araneae, Mimetidae): aggressive mimicry, araneophagy and prey specialization. Journal of Zoology, 210(2), 279-303.

Kloock, C. T. (2001). Diet and insectivory in the “araneophagic” spider, Mimetus notius (Araneae: Mimetidae). The American Midland Naturalist, 146(2), 424-428.

Kloock, C. T. (2012). Natural History of the Pirate Spider Mimetus hesperus (Araneae; Mimetidae) in Kern County, California. The Southwestern Naturalist,57(4), 417-420.

Castianeira: ant-like spiders

Posted on August 28, 2015 by cataranea

The spider genus Castianeira (in the family Corinnidae) is one of my favourites. These small spiders are rather elusive, but so beautiful! There are currently 128 known species in the genus, so I will only be able to highlight a small number in this post. This should nonetheless provide a glimpse into the diversity of gorgeous forms they take!

Castianeira dorsata from Arizona. Photo: Sean McCann

Natural History

Common names for the family Corinnidae include “ground sac spiders” (they used to be included in the sac spider family Clubionidae) and “antmimic spiders”. They are not all antmimics, but many species in the genus Castianeira are rather ant-like and are considered generalized ant-mimics.

Castianeira longipalpa, found under a rock near a lot of ants at Iona beach in Richmond, British Columbia. This species is thought to be a generalized mimic of myrmecine or ponerine ants. Photo: Sean McCann

The species shown above and below don’t look especially like any particular species of ant, and their mimicry is “imperfect” – besides having fairly elongate bodies and stripes that might give the illusion of a third body segment, they look a lot more like spiders than ants. At first glance, however, they can easily be mistaken for ants (at least by humans). They are fairly ant-like in size and colour (often red or brown and/or black) and they move around a lot like ants, waving their front legs like antennae, and bobbing their abdomens in ant-like fashion. These spiders are often found in close proximity to ants, which provides some support for the idea that they are in fact mimics. They might benefit by looking ant-like to predators who find ants distasteful (and don’t look too closely).

Castianeira sp. from near the Soutwestern Research Station in Arizona. Photo: Sean McCann

Some species, like the one from Singapore below, are a little more ant-shaped, but their morphology is not as extremely modified as some other kinds of ant-mimicking spiders (like this one photographed by Alex Wild).

Castianeira_sp_singapore_HKTang_CC BY-NC-ND 2.0

Castianeira sp. from Singapore. Photo: H. K. Tang, licensed under CC BY-NC-ND 2.0.

Some Castianeira species are thought to mimic velvet ants (Mutillidae), rather than ants. Mutillids are not actually ants but wasps, and the females are wingless and brightly coloured, with extremely painful stings. In this case, harmless Castianeira spiders might benefit by looking like the much more dangerous velvet ants, and thus be avoided by predators (this is called Batesian mimicry).

Castianeira occidens from South Fork, Arizona. This spider was found running (fast!) across a forest path during the day. Photo: Sean McCann

As with the ant-like species, these spiders tend not to look very much like any particular species of velvet ant. They are generally mutillid-like in their movements and in that they have bright markings on their abdomens reminiscent of the warning colouration (aposematism) of velvet ants, like the one below.

Velvet ant from French Guiana. Photo: Sean McCann.

One of the most gorgeous spiders I have ever seen is the Castianeira dorsata (below, and at the top of this post) that Sean found wandering around by a stream one evening while we were staying at the Southwestern Research Station in Arizona. These spiders are supposed to be active during the day, so it was interesting to find this one running around in the dark while we were out with our headlamps searching for wolf spiders. Obviously, looking like a velvet ant isn’t going to fool anyone if it’s so dark they can’t see how brightly coloured you are.

Castianeira dorsata from Arizona. Photo: Sean McCann

I don’t know of any velvet ants that look much like this (although many are bright orange), but I just can’t get over how beautiful this spider is with its sunset-like stripes on the abdomen and a bluish iridescence on the carapace. Even more dramatic is what I like to call the “tiger-striped” Castianeira below. The photo below shows the relative size of Castianeira amoena on a human hand. I imagine they would be as fearsome or even more so than a tiger if they were blown up to a comparable size. In reality however, these spiders are extremely shy, and very fast runners when they are disturbed (as by humans!) – so all the photographs in this post are real treasures.

Castianeira amoena. Photo: promiseminime, licensed under CC BY-NC-ND 2.0.

Finally, the spider below is not a Castianeira, but a species in the related genus Graptartia (also in the subfamily Castianeirinae). I couldn’t resist adding it because it shows such a beautiful example of mimicry, and one that’s much more specific than the examples above. The velvet ant model and spider mimic where found within a few metres of another (one of the criteria for Batesian mimicry is that the model and mimic have to be found in the same place!) and the photographer then managed to move them so that he could capture them together in the photo below. Wow!

Graptartia_granulosa&velvet_ant_PaulBertner

Graptartia granulosa mimic and velvet ant model from Tanzania. Photo: Paul Bertner (used with permission).

Notes on Identification

Usually these spiders are pretty recognizable because of their distinctive colouration, but some of the less bold ones can be confused with other ant-like spiders (like Micaria). Spiders in the genus Castianeira have 8 eyes in 2 rows. The posterior eye row (the upper row, in the photo below) is slightly wider than the anterior (lower) row with all four eyes about the same size. Both rows are slightly procurved (curved toward the front end of the spider). The anterior median eyes (front and centre) can be slightly smaller to much larger than the other two in their row.

Castianeira_cingulata_sankax_CC BY-NC 2.0

Castianeira cingulata portrait, showing the eye arrangement. Photo: sankax, licensed under CC BY-NC 2.0.

The last (hindmost) pair of legs is always longest, followed by the first (frontmost) pair, and the abdomen is often decorated with bands of white scale-like setae (hairs).

Dorsal veiw of Castianeira longipalpa from BC. Photo: Sean McCann.

References:

Dondale, C. D., & Redner, J. H. (1982). The insects and arachnids of Canada. Part 9. The sac spiders of Canada and Alaska. Araneae: Clubionidae and Anyphaenidae (No. 1724).

Reiskind, J. 1969. The spider subfamily Castianeirinae of North and Central America (Araneae, Clubionidae). Bull. Mus. Comp. Zool. 138(5): 163-325.

spiderbytes

This is a blog about spiders (and other arachnids)

Category Archives: spider diversity

Meet the spiders in your house with Travis McEnery!

Spider sex and silk: From mating threads and bridal veils to nuptial gifts and silk-lined chambers

Fishing spiders (family Pisauridae)

Yellow sac spiders (family Cheiracanthiidae)

Myth-busting

Zora & Syspira: wolf-like prowling spiders

Rhomphaea: ridiculously long theridiids

Oecobiidae

Myrmecophilic spiders

Pirate spiders

Castianeira: ant-like spiders