This post will probably be shorter than the last one, as it continues on from it. Again, I’ll posting photos of the Mascot Mines, this time outside the visible spectrum, so read the last post if you want some history on it. I went over most of the information last time about the mine, including why it was created, the routes to the mines, the venomous spiders, the many, many, many stairs, and…
…wait, I didn’t mention the venomous spiders?
Yeah, there’s totally venomous spiders there. See?
Are you sure I didn’t mention it? I’m fairly sure I said something. I remember the old crone being covered in them. Fine- Mascot Mines part 2 is on hold, because I want to talk about a spider I saw. I’m not getting paid for this, so I can do what I want, and I want to talk about a spider!
Obviously, that’s a black widow spider. I’d never seen one before, and I didn’t know they even lived in British Columbia.
Specifically, it is a latrodectus hesperus, or Western Black Widow. There are a number of black widow species worldwide but the Northern Black Widow is the only other species in Canada; it appears mainly in the USA but the range reaches southern Ontario.
…I think that maybe it was named by an American. In fact, ‘Southern Ontario’ is fairly far south. I think the Western Black Widow might even live further north, as BC’s border is at the 49th parallel and Ontario starts at 41° 41′ North … so maybe it was named by a geographically confused American. At least BC’s spider is in the west, so he got that right.
The western black widow females are sheer glossy black, with only the red hourglass on their abdomen to break up the darkness, and they look both incredibly cool and incredibly terrifying.As you can guess from the fact that I took a bunch of photos of it, Cool won out. Still, I couldn’t help feeling sorry for the spider I saw; after all, she’s a widow. In fact, her poor husband is lying dead right there!
The female black widow is the black and red one, and the males are a dull brown or grey colour. Or in this case, the colour of dead.
To be fair, this spider wasn’t even seen at the Mascot Mines, but rather outside the Snaza’ist Discovery Centre(run by the Upper Similkameen First Nations band), which ran the tours to the mine. To be even fairer, this spider was by a well-trafficked doorway in the centre, probably the largest tourist attraction in the area right by the highway at Hedley. How many spiders would be tucked away in an abandoned complex of wooden buildings, only visted once a day at most? Maybe watch out if you want to stick your hand in any holes up there. Or maybe it’s too high at the mines for the spiders to survive. I really don’t know, so let me revise my warning: maybe stick your hand in some dark holes up there, and let me know how it goes. I’m always happy to learn new things. These spiders are also much smaller than I thought they would be; I see bigger spiders all the time! They must just be good at hiding. Did you check all the crevices in that hole?
Anyways, Here’s the poor lonely widow again. I’m doing my usual thing and breaking up the photo above into the red…
Green…
… and blue colour channels
The hourglass is mostly noticeable in the red channel, but still much darker than I expected. You can’t distinguish it in the green or blue channel, but if you look very closely in the blue channel, it seems that it might even be a little darker than the rest of the exoskeleton. It is more clear when the images are quickly alternated. Which means it’s GIF time again!
I didn’t get any closer because I have no idea how close is ‘too close’; like I said, I don’t have much experience with venomous things. Anything that will kill you up in northern BC is big enough that you know it’s going to kill you. That’s reassuring, isn’t it?
If the spider’s hourglass is clearest in the red channel, and darker the shorter the wavelength, how does it look outside the visible spectrum? does this trend hold? It’s really hard to estimate a trend based on three data points? I wanted to do a comparison in different spectra, but the spider built it’s web in a dark corner by the door, and the wind kept the spider vibrating, meaning a long exposure was not an option. Ultraviolet was out, and even my short pass filter(allowing blue, violet, and UV light to pass into the camera) was a little blurry.
Still, it’s enough to see that the hourglass does not come back in any significant way in the UV range; the abdomen would look brighter in the above photo. Maybe, if I took a full UV photo, there might be a small difference, but any larger UV variation does normally show up in the short pass filter as well, usually as a slight discolouration or a different shade. The hourglass is still invisible. The dead male spider is still dead.
My camera is better at the other end of the spectrum, so how does the spider look in infrared? For this, I just stuck with one filter, my Zomei 850 nm filter. I don’t usually use this one, as I default to Zomei’s 760 nm or 950 nm filter, but I had it on this trip. the 850 nm filter still allows for a quicker shutter speed, but is deep enough into the infrared range that there isn’t any traces of colour in the resuluting photo. As far as I can tell, no visible light can pass through this filter.
Even in the near-infrared range, the hourglass pattern in clearly visible. I’d say that the hourglass is only visible in the red wavelengths and longer, and not in the short wavelengths. I can’t prove it’s invisible in the ultraviolet spectra, as my photos aren’t good enough, but I do think it’s invisible. If I had to derive a conclusion… well first off, I’m sorry you have to rely on me, but I couldn’t find any actual scientific literature on this through cursory searching, and didn’t want to spend a week combing through the literature. I think that…wait a second…
Seriously. I looked again. If I look for ‘Black Widow’ and ‘Infrared’, I get a bunch of links for night vision scopes; if I look for ‘Black Widow’ and ‘Ultraviolet’, I get a bunch of links to buy a film with a defunct digital download code. And while on the topic, why is a digital film distribution service called ‘Ultraviolet’? THAT’S THE CRAPPIEST SPECTRUM! Everything looks hazy and washed out! No wonder they shut down. Look. I don’t want to do this. I just want to make dumb jokes. I think I’ve proven that I should not attempt to be scientific. Are you sure you can’t find someone more qualified to make a conclusion for you? Maybe an arachnologist, or biologist, or basketball player? Anyone? Fine, be that way: Conclusion time.
Conclusion the First: The spiders are camouflaged to other insects. Many insects can see short wavelengths and ultraviolet light, and spiders feed on insects(I did double check this for black widow spiders, but I don’t why I did that… seriously; they build webs, and the webs are covered with the desiccated corpses of various insects, and I saw that first-hand and took pictures of it). After even more exhaustive research, I’ve found that the natural habitat of the black widow spider is not a brightly coloured pink building, but rather in that scary nebulous place known only as ‘nature’. As I’ve show from other posts, foliage is much darker in the short wavelengths, and in ultraviolet photos, it appears almost black. By the same token, dark holes are usually dark. A black spider would blend in perfectly, and to an insect, the black widow would be all black… At the same time, the spider does have one bright mark on it, the red hourglass. Why?
Conclusion the Second: It’s a warning colour. Most larger vertebrate species can see the longer wavelengths, even if most can’t distinguish between red and green. Birds CAN see UV light, but also red light, so the hourglass would still be visible to them. Many birds eat spiders and small insects, so it would be useful if there was a bright colour on the venomous ones that the bird could see; this distinguishes the food category ‘insects/spiders that might result in a small itch if they bite me’ from the catagory ‘insects/spiders that will agonizingly kill me if they bite me’. Are there potential predators to the black widow that can see in the near-infrared range? None that I’ve been able to find, but it wouldn’t surprise me. It could also be that the red spot evolved to be visible in the red wavelength, but was also visible in infrared as a side effect. Evolution is messy that way.
Conclusion the Third: It’s camouflage AND a warning, at the same time. It seems so strange, but the above two conclusions aren’t mutually exclusive. The spider is camouflaged from those it needs to hide from, and has a bright spot for those that need to see it. Insects can’t see red, but many of the spider’s predators can see it, and are either smart enough to avoid it or dead enough to join the ex-spouse.
Conclusion the Fourth: If their warning colouration is also a camouflage, then black widows are even cooler and more terrifying than I originally thought.
Conclusion the Fifth: The dead spider is dead in all spectra. I think it might be dead.
Conclusion the Sixth: Finally, for the sake of maintaining my sanity when doing research, I am never, never, NEVER again writing about something when a blockbuster movie that shares a name with that same something is being released soon.
The above photos were taken with a modified Canon T3i Rebel camera
Parallel Views 