Long-Jawed Orb Weaver

2009 September 5

On July 19, I was up on the stamp sands from the old Copper Falls Mine with some friends[1], and decided to poke around a bit in the shrubbery growing along a stream bed. When I came out, I noticed this spider rapelling down from the edge of my hat:

Unfortunately, I didn’t have any of the add-on lenses for my camera with me, but I did the best I could. Fortunately, the spider was big enough that the pictures came out reasonably clear anyway. It scurried around pretty fast on the ground, making it hard to get pictures. But, one friend was sufficiently non-arachnophobic to be willing to get close up and take some pictures while the spider walked around on my hands (thanks, Mary Lynn!), which helped for getting side and face shots:




At first, I thought it was a lynx spider. But, after checking against the descriptions in “Spiders of North America”, I realized that the eye pattern was wrong, the legs didn’t have the spines that lynx spiders have, and the body didn’t taper correctly. Looking at the face, the eye pattern and the very long jaws, it was much more consistent with being one of the Long-Jawed Orb Weavers, probably in the genus Tetragnatha.



I didn’t see the web, but they spin a more or less classic orb web (the circular web with the strand spiraling towards the center). They are a bit different from other orb weavers, though, in that they normally spin their webs horizontally instead of vertically. They like to live in the bushes near streams and bodies of water, and it sounds like they spin their webs flat to catch mosquitos, gnats, mayflies, and other aquatic insects as they either hatch out and fly up from the water, or fly down towards the water from above to lay eggs.

I probably walked through her web while going through the brush, and she ended up dangling from my hat instead. Hopefully the ride didn’t disturb her too much.

[1] A lot of the copper mines in this area were mining native copper, which is pieces of actual metallic copper that are dispersed through the rock. These copper pieces ranged from microscopic flakes, to chunks the size of a small car. Mining the copper mainly consisted of digging up the ore, and smashing it with “steam stamps”, which were basically big automatic hammers. The rock would break, but the ductile copper just mashed into flakes. The copper flakes could then be screened out, or separated in machines that classified the particles by density (metallic copper is about 3 times denser than the average rock). Once the copper was removed, what was left was this dark-colored basalt sand, which was termed “stamp sand”. There are a bunch of areas where this sand was dumped, some of the stamp sand deposits are very extensive. Nothing much grows on it. This isn’t so much because of any toxicity, but because it is sand. The water drains right out of it in the summer, so anything growing in it dies and nothing really gets a foothold. Anyway, there are about 100 acres of stamp sand from the Copper Falls mine. One of my friends bought a bunch of the land that it covers really cheap years ago so that we could all get together and play there every summer.

4 Responses
  1. September 12, 2009

    Great info about the copper. I didn’t know you could find it in chunks. The colonists at Roanoke got along with the Indians by trading copper because the tribe near them were at war with the one that normally provided copper for tools. I had wondered how the Indians managed the smelt the stuff, but from reading this, it looks as though they didn’t have to smelt it much at all.

  2. September 15, 2009

    Occasional chunks of native metallic copper are fairly common in most copper ore bodies, even though most of the metal in them is usually in the form of copper sulfides. But, the copper deposits up here in the Keeweenaw Peninsula of Michigan are an anomaly in that practically *all* of the copper is present as metallic copper. There are none of the sulfide minerals that usually cause things like acid runoff and heavy-metal contamination at other copper mining sites. The mining methods here were thereofore much more focused on recovering the metal, and the environment is actually pretty much uncontaminated from past mining activity. The stamp sands mostly just lie there, they don’t appear to be actively poisoning anything. There is one bad bit where Torch Lake is contaminated by heavy metals (mostly lead), but that wasn’t actually from local ores – it was from lead-tin solder contained in electrical scrap that was brought in for remelting.

    Copper from here was apparently traded all over North America by the natives before the Europeans came over. At one point, before the Arizona copper deposits were discovered, it was thought that copper from the Keeweenaw was traded all the way to *Mexico* (which is why we have some streets with names like “Montezuma” and “Tezcuco” in town – people felt like they had a connection to the Aztecs).

  3. Joy K. permalink
    November 23, 2009

    Have you seen these spiders in the web? They position themselves with their 4 front legs stretched far out in front of their heads in a most un-spider-like configuration. They appear VERY long and thin, rather than rounded like most spiral-web spiders.

  4. November 24, 2009

    I’ll have to look for that. I haven’t done much photographing of spiders in the web so far, which is something I really need to do.

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