No Boy Scout

There’s (at least) two messages within that title, which you know makes me happy…

So, in going back through the folders in search of more subjects for the Profiles of Nature posts, I found some of those frames for which I’d said, “I need to write about that,” and then promptly filed them and forgot about it – this is a semi-regular occurrence. Lucky for all of us, I have a rampaging ego and go look at my own photos on occasion.

This is from a student outing, back in the fall.

long-jawed orb weavers Tetragnatha during courtship
We have here a pair of long-jawed orb weavers (genus Tetragnatha,) common spiders around water sources, in this case Jordan Lake. This makes only the second time I’ve caught spiders in “the act;” that’s the female on top (hunh hunh hunh) with the male grappling her chelicerae safely away while he prepares to inseminate her. I apologize for this, because if you don’t know what you’re looking for there isn’t the level of detail here to make it clear, and describing it isn’t guaranteed to fill in the gaps, but I wasn’t intending to do finely detailed macro work and thus wasn’t prepared with the macro flash attachment or the higher magnification lens, so I was shooting in available light with a larger aperture, and focus/depth suffered.

So, the male is largely vertical, and you can see the dark eyes all lined up. Below them (or to the upper right as far as the photo goes) sit the very large chelicerae, the ‘fangs,’ for which the long-jawed orb weavers are named – you can get better views here (male) and here (female.) You can just make out that the male has his wrapped around the female’s; it’s the darker orange bit near the top of the frame. The key bit is the pedipalps, the extra ‘legs’ or even ‘feelers’ that emanate from right alongside the chelicerae, thinner than the legs. One of the male’s is in plain sight and focus, crossing over his own chelicera, but the other is the key one, and it’s a bit unfocused; that’s it underneath the female’s abdomen with its big ‘boxing glove’ end. Again, you can see the difference in the male and female versions in those other links: the male has club ends, while the female has slender pointed ends. That’s because the male stores sperm within his, and ‘manually’ inserts this into the female’s epigyne, a flap opening near the base of the abdomen, which this frame is just short of illustrating.

Most people are familiar with the idea that the female spider may eat the male after mating, which can be true among certain species at least, but overall, courtship is often a highly contentious affair; it’s possibly the way that the female weeds out the less-capable males to ensure that her progeny is from tough genes. I’ve seen courtship a few times now, and in most of them the male is very quick to drop away from the female if she makes a threatening move – only to slip in again for another try, like a tipsy lounge lizard. In fact, seeing the unique chelicerae of this species in such use, I wondered if that was the true purpose, and had to go back through my photos to determine if it was only the male that had these hinged monstrosties. But no, the female has much the same, so this may only be a secondary, incidental purpose.

This would be an ideal subject for video, though exceptionally challenging. The magnification has to be pretty high, the focus bang on, the view unobstructed, the light adequate and from the right direction, and most especially, it’s very difficult to find a way to use a tripod, and not using one means so much focus change from either the camera movement or just the breeze shifting the breeding lair (which would be an issue even with a tripod) that sea-sickness is likely to be induced from such a video clip. Maybe someday.

But we come back to the title, where we find I’m unprepared for the subject matter, as well as creeping on the spiders during their private time. But hey, they could have pulled the shades if privacy was so important…

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