river spiders

If you’re thinking, “What the heck?” — you’re not alone. I happened upon the above Black Widow spider while trying to photograph some small gray Fishing spiders that were perched on rocks and gliding across the surface of the water along a river in central Oregon in late September. The gray spiders (see below) looked like some small species of Dolomedes and were behaving much as I’d expect them to, but what about that Black Widow?

I haven’t had much to do with Black Widows in the past as they aren’t usually found up here in the north. I have photographed one before though — was asked to take some shots of one that came in on some grapes and ended up in a natural history museum up here. I didn’t know they liked to get their feet wet — and perhaps they usually don’t — but this one didn’t seem to mind. Its pose almost reminded me more of some of the Dolomedes I’ve photographed in the past. So, what’s it up to? Opinions and guesses are most welcome.

I’m also not sure which species of Widow (Latrodectus) this would be. I did some checking around and am still unsure. It had what looked to be a couple of faint red marks along the center of the dorsum, which I take is common to the Northern Black Widow (Latrodectus variolus). I did use a small twig to try to turn the spider over so that I could take some photos of the underside of its abdomen. I managed to get a couple of brief looks, but the spider wasn’t in a cooperative mood, so I couldn’t hold the twig and shoot a photo quick enough before the spider flipped upright again. However, from the my brief glimpses, I’d say that the red hourglass on the abdomen looked to be divided across the center, rather than entirely red like the spider that I photographed at the museum.

By the way, after messing around with the twig and the spider for a little while, I wandered along the shore and mentioned to my travel pal, Wilbur, that I’d found a Black Widow in the water on the shore and described what I’d been up to. He paused in the middle of taking a photo, scowled (in what seemed like mild disapproval), and said, “You do know you’ll get pretty sick if you get bitten by one of those.” I shrugged, shot him a grin and said, “Yup… but don’t worry….I won’t take any chances.” He shook his head as he turned back to his work. I believe I heard him mumbling something about us being in the middle of nowhere away from any hospitals . . .

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12 Responses to “river spiders”

  1. Peter Says:

    The Black Widow photo is amazing. I am always impressed by your photography but you just raised your own bar.

    I am also with your friend, and the “stay safe” attitude. I know you won’t put yourself in a position of bad risk though.

  2. Mark Says:

    That behavior is unlike any I have ever seen, and there are lots of black widows around here. If I happen to turn over a rock around the house I always expect to find one. That means I handle things carefully. But I doubt you were in much danger. I have never seen a black widow do anything but try to escape when disturbed. I don’t think they jump. (Or do they? Hmmm.)

  3. burning silo Says:

    Peter – Thanks! It was such an unusual sight, and so interesting to see how the front pair of legs were poking down into the water. I have no idea of the reason for this. And yes, I’m pretty careful when handling all creatures, and actually prefer not to bother them at all — just take a photo and leave them to their business.

    Mark – From my own scant observations, I don’t think a Black Widow can move very fast except possibly when sliding along its web. The one that I photographed at the museum seemed almost ponderously slow. I suspect most encounters must occur when one might get into some clothing, or perhaps bite when it feels it’s being crushed. One of my field guides says that they like to hang around in outhouses – which could present a unique danger, I suppose! (-:

  4. robin andrea Says:

    When I worked at the university, the building I managed (the Press Center) was on the edge of a redwood canyon on one side and a large meadow on the other. We had a wide range of wildlife that passed through and around the building. I had to do orientations for students who would be using the Press Center. I always had to point out the black widow webs that showed up every year. They liked to build their nest under desks (I found one under mine in a pile of envelopes), and in stacks of old newspapers that accumulated every year. We could often find the spider just by looking for the pile of dessicated insect remains. I never saw the black widows move very much, and thought that they stayed in their webs waiting for their food to come to them. It is surprising to see one out like in your photograph, dangling those legs into the water. What a beauty.

  5. Xris (Flatbush Gardener) Says:

    My first thought was that it was using the surface tension of the water in the same way that it uses its web: to detect vibrations of prey. But your note about their sluggishness doesn’t seem to fit that behavior.

    It looks like its face is in or at the water’s surface. Maybe it was drinking? The front legs are out to provide support, using the surface tension.

    I notice its back/dorsum looks “dented”: perhaps it was injured?

  6. burning silo Says:

    Robin – I think you’re quite right about their usual hunting strategy. I think they usually make their web and hang out in it waiting for prey to come along.

    Xris – I agree that the behaviour of these spiders doesn’t really seem to fit with what it’s doing. I did wonder about the head end of the spider being at the water’s edge. Normally, I don’t think spiders drink water — probably just requiring body fluids from their prey — and also, I think they can survive very long periods without fluid — just thinking of how a spider can remain alive in the corner of a room for weeks. However, conditions in this region were quite dry and perhaps prey were few. Hard to say. The abdomen looked a bit dented to me too, in this and a couple of the other photos. I don’t know if that might indicate and injury, or perhaps could be a sign of desiccation? One thing I do know is that the abdomens of the big Argiope spiders here at the farm sort of “collapse” and look wrinkled after they lay eggs. Also, I have watched Goldenrod Crab Spiders (Misumena vatia) stay guarding their leaf-wrapped egg cases for 2 or 3 weeks (or more) while the spider slowly wasted away and the abdomen slowly collapsed. Perhaps that was the case with this spider. I’ll see if I can get David Shorthouse from the Canadian Arachnologist website to take a look at the photo and maybe offer an opinion.

  7. Mark Says:

    I have heard stories about men in particular being victims of black widow bites when using outhouses. Thank goodness we have indoor plumbing. And, so far, no black widows inside. Although I find scorpions occasionally.

  8. kara Says:

    Amazing spider pics – thanks for sharing.

  9. burning silo Says:

    Here’s a follow-up on the Black Widow spider’s behaviour. I’ve just received a response to my email sent to David Shorthouse at the Canadian Arachnology website. He writes:

    You are correct, widows do not drink water; they do indeed get all the fluid they need from their prey items. I suspect however they might also get some water intake by sucking up dew droplets from their webs in the early morning hours. Similarly, orbweavers get quite a bit of water when they consume their webs each morning.

    My best guess for the very unusual behavior you captured is that the widow is/was parasitized by a nematode, which would also explain its collapsed abdomen. Very often the behavior of spiders infected by these creatures, which can take up almost the entire volume of their abdomens, shifts dramatically to seek out standing water.

    Pretty interesting stuff and not at all what I might have guessed!

  10. burning silo Says:

    Mark – One of the things I find a little difficult about traveling is keeping in mind that there may be venomous spiders, snakes, scorpions, etc… around. Up here in Ontario, we have only one species of venomous snake and it is so rare and in such a restricted range that I’d feel elated if I ever manage to set eyes on one. When I’ve traveled on the west coast, my friends occasionally warn me about spiders, and the signboards at almost all hiking trailheads have posters warning of the danger of rattlesnakes — and also for mountain lions. Perhaps I should post some photos of warning signs seen along the way as they’re kind of interesting.

    kara – Thanks! Glad you enjoyed the spider photos!

  11. Julia Russell Says:

    I happened on to this site by accident. My husband and I just moved to Oregon and I had not seen any Black Widows. We’re from California where they are very common. I was trying to find out if Oregon had them as well. I guess you answered my question. I read your description of the one at the water (I’ve never seen that before either). However before I stumbled onto your page I found this one at http://kaston.transy.edu/widow.html. It showed three different types of Widows. The one you described with a seperated hour glass (the website says) is a “Northern Black Widow”. “New England and adjacent Canada south to Florida, and west to eastern Texas, Oklahoma and Kansas. More common in the northern part of the range”. I wonder if this is the area this widow came from. If it is, I wonder if it is common for this species to be so comfortable around water. I have a phobia of Black Widows. They scare me. My husband pickes them up with his bare hands and lets them crawl on him.(I definetly don’t advise it.) Yuk! He has been bitten a few times. However he has never been bit when picking them up though. The first time was in bed. It bit his leg. He was sick for three days. He vomited a couple of times and had a stomach ache. He thought it was the flu until he seen the bite. A round nasty hole. He has been bit a couple of times since but doesn’t get sick anymore. I too have been bitten by one. I felt it bite, but never seen it. I’m pretty sure it was a Widow. A couple of days later there was a perfectly round hole in the side of my right breast where I felt the sting. It looked just like a bullet hole. It was very deep. I still have the scar. I only had an upset stomach. I’m sorry for rambling on but Black Widows are still fasinating even though I fear them so much. I have tried to photograph them but could never get the right angle. Your photos are great. – Julia

  12. burning silo Says:

    Julia – As you’ve gathered, there are Black Widows in Oregon. I guess they are common enough, although perhaps not so frequently found as in California. Btw, they do have another venomous spider in Oregon – the Hobo spider. Tell your husband *not* to pick up one of those though! There’s a web page about them on this Oregon Department of Agriculture site. It says that people sometimes mistake the Hobo spider’s bite for that of the Recluse spider, but that the Recluse is not found in Oregon.
    http://www.oregon.gov/ODA/PLANT/ippm_spider.shtml
    Thanks for writing about your experiences with Black Widow spiders. I’d heard they aren’t as dangerous as some people say, and do know someone who got bitten by one and was sick for a couple of days but then okay, but I was curious about how strong a reaction a person might have if bitten.
    Glad you enjoyed visiting my blog!