Spiderday (#27)

I know, I know… it’s been too long since the last SPIDERDAY post! The end of term proved busy, but I’m trying to get back on track. So: here are some of the best arachnid-themed stories of the past couple of months. I hope you enjoy all the eight-legged greatness! Let’s start things off with a beautiful photo:

Zora hespera, photo by Sean McCann

Zora hespera, photo by Sean McCann



Spiderday (#26)

Finally, SPIDERDAY is back! (Sorry about the delay – it’s been a busy term, so I’ve not been able to keep up on the blogging). Here are some Arachnid-themed stories pulled from the web over the past month or so:

Two of my favourite Arachnologists (Sean and Catherine) have been on a great SPIDER TRIP adventure! This is one of the species they stumbled across in Texas. Yes, it's a brown recluse (photo by S. McCann).

Two of my favourite Arachnologists (Sean and Catherine) have been on a great SPIDER TRIP adventure! This is one of the species they stumbled across in Texas. Yes, it’s a brown recluse (photo by S. McCann). Check out more photos from their adventure, here.


Bog spiders: family composition and sex ratios

This is the second post by Honour’s undergraduate student Kamil Chatila-Amos – he has been busy working on identifying LOTS of spiders from bogs of northern Quebec. His first blog post introduced his project: this one gives a glimpse into the data…

My project is focused on studying spiders from bogs in the James Bay region of Quebec. Five bogs along the James Bay highway were sampled with pan traps every week for four sampling periods. In the full project I’m looking at how abiotic factors (i.e. pH, water table, latitude, etc.) and the plant community affect the arachnid community composition. For now, let’s look at how the spider families are distributed in these sites:

bogSpidersThe first thing that might strike you if you are familiar with the area and its spider fauna is that in 4 out of 5 sites, neither Lycosidae (wolf spiders) nor Linyphiidae (subfamily Erigoninae) are the most abundant family. Previous studies in similar habitats tend to find a much greater proportion of those two taxa (Aitchison-Benell 1994; Koponen 1994). All sites except the first have more Gnaphosids than Lycosids. However, the breakdown within families is very different. Whereas the Lycosids are represented by 19 species, there were only five species within the Gnaphosidae. Even more impressive is that one Gnaphosidae species represents 99% of the family. Indeed, Gnaphosa microps alone represents a fifth of all arachnids I collected.

I’ve come to like Gnaphosa microps a lot! The family Gnaphosidae is pretty easy to identify thanks to their long and separate spinnerets, colour and eye placement. Even the palps, which are unique to species, are fairly easy to recognize. It ranges in size from 5.4 – 7.1 millimeters which is a large enough size so it isn’t a hassle to manipulate.

Gnaphosa microps, seen from above. Photo from the Biodiversity Institute of Ontario through Barcode of Life Data Systems

Gnaphosa microps, seen from above. Photo from the Biodiversity Institute of Ontario through Barcode of Life Data Systems

Gnaphosa microps is by no means a star of the spider world but we still know a fair bit about it. It is a holarctic species meaning it can be found in almost all of the northern hemisphere, even as far as Turkey (Seyyar et al. 2008). It is usually found in in open boreal forests, alluvial meadows and bogs. A nocturnal species, it spends its days in a silk retreat under moss or debris and hunts at night by catching prey on the ground (Ovcharenko et al. 1992). Even though sampling has been done very near my sites and in similar habitats (Koponen 1994) I still haven’t found another study where it was the most abundant species.

Another interesting tidbit about this species is just how skewed their sex ratio is. According to my data, males outnumber females almost 10 to 1! Now this does not mean it is always like this in nature, this ratio can be explained by sexually dimorphic behavior. This means that the males would behave differently than females in a way that would increase their odds of falling into traps. Indeed, according to Vollrath and Parker (1992) spider species with sedentary females have smaller, roving males. And like their model predicts the G. microps males are a bit smaller than the females.

Sex ratio of Gnaphosa microps, collected in bogs

Sex ratio of Gnaphosa microps, collected in bogs


So what’s next? I still need to retrieve the COI barcode of all my species and that will be possible thanks to the University of Guelph’s Biodiversity Institute of Ontario. This is to make sure my identifications are indeed correct. As a first time spider taxonomist it’s great to be able to confirm my work in a way that still is not widely available. Today I received the plate in which I’ll load the spider tissue and I am amazed at how tiny it is. I guess they just need 2mm per spider but I still expected it to be much more impressive. Hopefully I don’t get any nasty surprises once the DNA data comes back, although some of those tiny Linyphiids did give me a pretty bad headache…



Aitchison-Benell CW. 1994. Bog Arachnids (Araneae, Opiliones) From Manitoba Taiga. Mem. Entomol. Soc. Canada 126:21–31.

Koponen S. 1994. Ground-living spiders, opilionids, and pseudoscorpions of peatlands in Quebec. Mem. Entomol. Soc. Canada 126:41–60.

Ovcharenko VI, Platnick NI, Sung T. 1992. A review of the North Asian ground spiders of the genus Gnaphosa (Araneae, Gnaphosidae). Bull. Am. Museum Nat. Hist. 212:1-92

Seyyar O, Ayyıldız N, Topçu A. 2008. Updated Checklist of Ground Spiders (Araneae: Gnaphosidae) of Turkey, with Zoogeographical and Faunistic Remarks. Entomol. News 119:509–520.

Vollrath F, Parker GA. 1992. Sexual dimorphism and distorted sex ratios in spiders. Nature 360:156–159.

A Tangle of Opiliones

The results are in!! Last week I ran a poll to get help in picking the best name for a congregation of Opiliones (i.e., Daddy long-legs, Harvestmenpersons). HUNDREDS of you voted, but the clear winner, with just about 55% of the votes is…

“A Tangle of Opiliones”


A congregation of Opiliones (photo by D. Ringer, reproduced here under CC License 3.0)

This name was proposed by “Antnommer” on Twitter, and it is quite fitting. When thousands of Opiliones hang out together, it does indeed look like a full-on tangle of Arachnids.

Thanks, everyone, for participating in the poll, and helping to find a perfect collective noun for these astounding Arachinds.

Here are the poll results, for those interested:

PollResultsAnd some of the “other” suggestions:


Here’s another video to illustrate a rather fine tangle of Opiliones


What do you call a congregation of Opiliones? (Poll)

The Arachnid order Opiliones are interesting animals, although vastly understudied. In the English speaking world, they commonly known as Daddy long-legs, Harvestmenpersons, or Shepherd spiders. Opilio, in latin, refers to “shepherd”, and many temperate/northern species have exceedingly long-legs, perhaps in reference to Shepherds on stilts, watching their flocks. The name ‘harvest’ likely refers to the natural history of some species who tend to see higher population numbers in the autumn (‘harvest’ season in the north). Many species are also known to form very dense ‘congregations’, sometimes numbering in the thousands.


A congregation of Opiliones (photo by D. Ringer, reproduced here under CC License 3.0)

I was doing a bit of art on the weekend, and was drawing such a congregation, and this led me to consider what to call a collection of Opiliones. There are great sites out there devoted to Animal Congregations, but none of them had a collective noun for Opiliones (spiders, by the way, are sometimes referred to as a clutter or cluster)

Time to change that. After some Twitter discussions, I present to you a Poll, and I am looking for your votes!


A congregation of Opiliones.

A congregation of Opiliones.

I’ll leave this Poll open until around the 8 of March – and then write an update! Please share!

…for inspiration, here’s a video for you:

Will spiders bite my dog?

I field a lot of questions about spider bites, and I have argued that spider bites are exceedingly rare (for humans). But what about our pets? Do our furry friends get bitten by spiders? If they get bitten, how do they react? Let’s look at this, move beyond anecdotes, and see what science has to say on the topic!

Can spiders bite my dog or cat?

The short answer to this is: YES. Some spiders are physically capable of biting mammals, including dogs and cats.


This is my dog, Abby. Should she be scared of spiders?

The longer answer is that we really don’t know about this for the vast majority of spider-pet interactions, and even if spiders can bite mammals, I would argue that such events are relatively uncommon. Spiders certainly don’t hunt dogs or cats, and when bites do occur, they are likely quite accidental. Your puppy Ralph can be quite energetic and rambunctious, and stick his snout into a dark corner which may be home to an arachnid. I’ve certainly seen my cat “play” with insects and spiders, and ping-pong an arthropod across the kitchen floor. However, we certainly have to get a little lucky to see an actual spider-pet interaction, and dogs and cats can’t tell us whether they have been bitten by a spider. Proper verification of any bite requires evidence.

In some cases, the evidence isn’t in dispute, such as the paper by O’Hagan and colleagues who state quite clearly in their peer-reviewed paper:

Two 9-week-old Chihuahua pus weighing 960 grams and 760 grams were seen to be attacked and bitten by a large black spider. The spider was killed” (O’Hagan et al. 2006).

Right: the puppies were seen to have been bitten by a spider, and presumably the pet-owners know what a spider looks like. Also, that paper was co-authored by a well-known Arachnologist, Dr. Raven – having an arachnologist involved in these studies is important, and gives credibility to the incident. This is a good example of a verifiable interaction between dogs and spiders.

There’s another detailed paper by Isbister et al., outlining spider bites (in the family Theraphosidae, a family of Tarantula spiders) in humans and dogs: their evidence isn’t in dispute either, and in two cases, the human was bitten just after the dog was bitten. That’s pretty clear!

Without clear evidence, however, it becomes tricky: there’s a case report of a Brittany spaniel being brought to a hospital, with “swelling on its muzzle, left of the midline” (Taylor & Greve 1985). This became a ‘suspected’ case of loxoscelism, and assumed by the authors to be caused by the brown recluse spider. However, diagnosis of loxoscelism is very difficult, and other more probably causal agents could be investigated. Stated another way: it may not be the spider. Don’t blame the spider without adequate evidence. As Rick Vetter states on his excellent website:

There are many different causative agents of necrotic wounds, for example: mites, bedbugs, a secondary Staphylococcus or Streptococcus bacterial infection. Three different tick-inflicted maladies have been misdiagnosed as brown recluse bite…” (Rick Vetter, accessed Feb 9 2015)

It’s also very tricky to look at a ‘wound’ on a pet and determine whether or not a spider was involved. I would suggest if there are multiple wounds, or lacerations, multiple bumps and bruises, it is unlikely to have been caused by a spider, and other more likely causal agents should be investigated (e.g., punctures, skin reaction to something, or perhaps an insect sting, or fleas).

So, bottom line: although I think direct interactions between spiders and our pets are relatively rare, spiders are certainly capable of biting our dogs or cats.


Do cats and spiders mix?

What happens if my pet is bitten by a spider?

If there is clear evidence that a spider bit your pet, there are really only two outcomes: nothing will happen (or your pet may exhibit mild reactions that may not be immediately obvious), or there will be clear, definable symptoms, and these may lead to more serious consequences.

I think the first scenario is more common than the latter, largely because we just don’t have a good way of tracking the frequency of spider-pet interactions, and as is the case with humans, the vast majority of spiders probably aren’t venomous to our pets. Our pets certainly get ‘mildly’ sick all the time – I think of the times that my dog got an upset stomach, and I always assume she tracked down some ‘snacks’ when on an off-leash run (I think she is quite fond of rabbit droppings…).

Science does provide us some data about more serious reactions when our pets do get bitten by certain spiders. The paper by Isbister et al., from 2003, is quite detailed, and gives case studies of a number of verified bites by spiders on humans and canines in Australia. Here’s the alarming part:

There were seven bites in dogs, and in two of these the owner was bitten after the dog. In all seven cases the dog died. In one case… the Alsatian died within 2 h of the bite. In two cases small or juvenile dogs died in less than an hour…” (Isbister et al.)

In this paper, the effects on humans were relatively minor, but this was not the case for our furry friends – reactions were severe and fast and resulted in death. The poor little Chihuahua pups mentioned earlier were equally unlucky, as reported by O’Hagan et al. Although both of these studies were from Australia, and involved only one family of spiders, it’s certainly scientifically interesting that canines were affected so strongly, and their reactions provide opportunities to further research the components of spider venom (e.g., see Hardy et al 2014).

There is also some evidence that cats may be affected by spider venom: research reported by Gwaltney-Brant et al, and Hardy et al, stated that toxicity studies result in fatalities of our feline friends:

Cats are very sensitive to the effects of widow venom. In one study, 20 of 22 cats died after widow-spider bites, with an average survival time of 115 h. Paralysis occurs early in the course; severe pain is evidenced by howling and other vocalizations…” (Gwaltney-Brant et al.*)

That’s pretty grim. Interestingly, this case reports on envenomation by widow spiders in the genus Latrodectus (e.g., the genus that includes all the black widow spiders that occur in North America) – these spiders are relatively common in some habitats, and can certainly live in proximity to humans. Looking at Australia again, Hardy et al. state that cats are seemingly unaffected when bitten by female funnel-web spiders in Australia. So,  effects of spider venom on cats and dogs differs depending on the type of spider, and even our pets aren’t likely to respond the same way to different kinds of spiders. Clearly, it is difficult to generalize about any of this!


Black widow spider – bad for cats? (photo by Sean McCann)

In sum, I have presented some details about spiders and how they might interact with our beloved pets. It’s fair to say that our pets certainly may get bitten by spiders, but overall I would argue such interactions are relatively rare. However, dogs and cats are certainly not immune to spider venom, and there is evidence to suggest they might have strong negative reactions to spider bites.

Despite this, I don’t see this as reason to panic or start stomping on any arachnid that wanders across your living room floor. The evidence we have is still relatively limited, and we just don’t have much information about effects of venom on pets, for those spiders that commonly inhabit our homes. I also think the lack of evidence is important to mention: if our pets were getting bitten by spiders on a regular basis, there would be more papers on the topic, and certainly more cases where anecdotes made the transition to evidence.

I think it’s possible to love your pets AND be an arachnophile. That’s certainly how I live my life.

[A BIG thanks to Maggie Hardy, Daniel Llavaneras and Catherine Scott, for helping point me to literature on this topic]


Hardy, M.C., J. Cochrane and R.E. Allavena (2014). Venomous and Poisonous Australian Animals of Veterinary Importance: A Rich Source of Novel Therapeutics. Biomed Res. Intl. doi: 10.1155/2014/671041

Isbister, G.K. J.E. Seymour, M.R. Gray, R.J. Raven (2003). Bites by spiders of the family Theraphosidae in humans and canines. Toxin doi:10.1016/S0041-0101(02)00395-1

Gwaltney-Brant, S.M., E.K. Dunayer and H.Y. Youssef. (2007) Terrestrial Zootoxins. Ch. 64 in Veterinary Toxicology (Edited by R. C. Gupta).

O’Hagan, B.J., R.J. Raven, and K.M. McCormick (2006) Death of two pups from spider evenomation. Aust. Vet. J. 84: 291

Taylor, S.P. and J.H. Greve. (1985) “Suspected Case of Loxoscelism (Spider-bite) in a Dog,” Iowa State University Veterinarian: Vol. 47: Iss. 2, Article 1.


*I was not able to access or read the original paper upon which this statement is based (Peterson and McNalley 2006 Spider evenomation: black widow, in Small Animal Toxicology, 2nd edition)

© C.M. Buddle (2016)

Frozen spiders

Winter has arrived here in the Montreal area. Brrrrrr. Last night was below -25C, there’s a bitter wind, and about a foot of snow on the ground. I found my warm mitts and down jacket, but our arthropod friends don’t have this luxury! This time of year really gets me thinking about how spiders are handling the weather….

What do spiders do in the winter?

Some spiders don’t overwinter at all, and instead die at the end of the Fall, with their hardy egg cases doing the overwintering. Many other spiders, however,  do remain active under the snow, in a little zone called the ‘subnivean zone‘ – between the snow and the ground. Others hunker down, nestled in leaf litter, under bark, or in otherwise concealed locations. On slightly warmer winter days, spiders can also become quite active on the snow surface. But all of this is generally not enough to guarantee survival, because even subnivean zones and hidey-holes can get very cold.

Maybe they freeze, and come back to life after it warms up? You may be inclined to think so – it certainly happens with a lot of insects. And, check out this photo that popped up on Twitter a week or so ago, by Nash Turley. It shows a fishing spider under a layer of thin ice, and it was still alive after Nash helped it out of its icy tomb. What the heck?


A fishing spider, under ice.

Did this spider  ‘flash freeze’, and like a good science fiction movie, pop back to life once it warmed up?

Probably not… I think ‘flash frozen’ spiders probably won’t survive. The literature generally suggests that spiders are not freeze tolerant. In other words, their tissues cannot survive the process of freezing, and ice will cause irreparable damage. Instead, I suspect Nash’s spider was already prepared or preparing for winter, and got trapped under the ice, but hadn’t yet frozen. It’s physiological adaptations involve some nifty and super-cool tricks.

Spiders are generally thought to be freeze avoidant* (e.g. here’s a paper on this), and through the process of accumulating glycols in their blood (i.e., antifreeze), are able to supercool. This means their tissues remain unfrozen at temperatures well below freezing, because they have physiologically adapted via the production of special antifreeze compounds that stops them from turning into ice. It’s a neat trick, and one that is relatively common in the invertebrate world. Of course, supercooling alone doesn’t ensure survival at extremely cold temperatures, and that’s where other adaptations come into play. Spiders will therefore find their way to the relatively insulated subnivean zone, or deep down in soil or leaf-litter. These behavioural adaptations (i.e., selecting overwintering sites), combined with supercooling superpowers, helps them get through the cold seasons. 

For me, I’ll stick to my down jacket, and enjoy how Hydro Quebec helps keep our buildings warm!

* actually, we don’t know nearly enough about spiders and their overwintering physiology. I should state that I assume most spiders are freeze avoidant, based on the current literature on the topic – there’s a LOT more species to study, though!