Back to the trough


It’s funny. I grew up with a fear of spiders, and while it is maintained that this is a learned response, I have a very hard time pinning this down – I can think of no specific education I received that set spiders apart, aside from the idea that some were venomous. I knew the same about snakes, yet had no fear of them at all, perhaps because my father and brothers not only handled them frequently, they kept several as pets. I discourage such things now, mostly because it is unnecessary and often detrimental captivity, but also because snakes (like countless non-domesticated species) really aren’t all that interesting to have around.

But spiders! There was definitely something about their appearance, their way of moving, that simply creeped me out, and those urges remain even though I’m in my forties now. At the same time, my fascination has grown, and I can handle most species voluntarily, though I can still get a chill if I discover one walking on me. They have such a wide variety of habits that they bear closer examination, and these are a case in point: the fishing spiders.

My first photo sale was of both a fishing spider and water striders, for an article in a water gardening magazine. The spider image, shown at right, was printed full page because, I’m guessing, they had too many readers. This is an example of one of the largest species, and almost certainly the largest species found in North Carolina – this one easily spanned my entire hand across the legs, tip to tip. They don’t spin webs, but instead capture their food by stalking like the various wolf spiders. In the case of the Dolomedes genus, they lie in wait on the edges of ponds and rivers, forelegs often resting on the water, and dart off across the water when an insect inadvertently splashes down, occasionally dining on small minnows and frogs as well. I suspect they also watch for species that hatch from an aquatic larval stage into a flying adult, emerging unprepared from beneath the surface.

Many spiders can get away with walking on the surface of the water, for two distinct reasons. The first of which is that they don’t weigh very much, so they can displace their weight against the surface tension easily, but more important is the structure of their feet, which contains tiny hairs that spread out on the surface, distributing their weight over a greater area. This can be selective as well – if they so choose, they can dive beneath the surface to escape predators or capture their own prey, as I watched one demonstrate the other day. When this occurs, the hairs on their bodies serve another purpose, which is to trap air against their abdomens where the breathing spiracles are located. In this way they carry their oxygen supply with them, and the various species of diving spiders will actually construct a dome-shaped web underwater and shed the air from their abdomen underneath this, forming a captured bubble beneath the surface in which they can retire, as well as raise their young.

They are not confined to water, and can be found in wooded areas fairly distant from ponds and streams – there’s a chance that the monster seen here is a fishing spider species, but many of the Dolomedes genus are hard to tell apart, especially when their abdomen is obscured by tiny horrors.

Most spiders are very shy in reality, and despite our impressions of aggressive behavior, will vastly prefer to run and hide at any sign of trouble – compare that to mosquitoes ;-). But one of the larger species was responsible for the most aggressive act I’ve seen from a spider, though I am forced to admit it was probably a case of mistaken identity. When I first moved to NC in 1990, I soon found that the nearby creek played home to some of these monsters, and one day I saw one disappear under a branch at my approach. Wanting a closer look, I took a small (but long) stick and started to ease it under the branch to flush the spider back out. But as the tip of the stick approached the hiding spot, the spider leapt out and seized the stick fiercely in its fangs for a moment, almost certainly under the impression it was a choice tasty insect of some kind. Such a display, however, does induce a bit of caution in one’s approach thereafter. This memory naturally came right to the front, many years later, when I was opening a wellhead and removing a bat of fiberglass insulation, to find another massive example perched on the insulation right smack on the opposite side as my hand. Knowing that, if startled, the spider would immediately run to the reverse, my movements became excruciatingly slow and careful. The spider graciously held still, sparing the immediate neighborhood a manly display of screams and leaping about.

Below, the largest example of a six-spotted fishing spider (Dolomedes triton) that I’ve seen, showing the way the water bends under her weight but still supports her. You might also notice that she has an undersized leg, presumably growing back after an altercation. This is the same one I witnessed diving under the surface in an eyeblink, and from the size of the abdomen, I’m guessing she’s not far from laying her eggs. In two locations within the past couple of days, I spotted well over a dozen of this species, often three or four examples within a meter of one another. Since this is the hatching season for many insects and tadpoles, I imagine it’s a great time for the spiders too. The one at the top of the post, a typical specimen spanning a little over a large coin in size, was one of many ignoring me because they were busy feeding – you can just see the captured delicacy if you look closely.

And yes, that’s my own finger – I do this strictly for blog posts, so you get a good idea of the scale. See how much I care for my readers?

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