Man Bits

Identification - Tetragnatha sp, long jaw spider.

I spotted a couple of long jaw spiders in the paddy field, not difficult, seeing as the 20m field is probably home to many hundreds, but these two were getting a bit close and excitable. Sure enough it was a male and female, but the male was being a bit hesitant, which of course is quite acceptable given the size of the female's fangs.

This is one of those spiders were both sexes are roughly the same size, the main size difference being that the female is full of eggs. I wasn't bothered about not getting the mating shot, as I have already blipped that one. The male however did present a good view of his bits, to give me something to prattle on about.

I wonder if at one time, spiders mated like all the other bugs, with abdomen contact. But with such a dangerous procedure, it is really no surprise that a better idea evolved. If this is what happened, it must have happened very early, as all spiders mate the same way. This would not be the first time that the bug came up with a better solution than nature, thinking about dragons and damsels.

I have discussed this before, but it has been a while.

The male picks up the seed on the tip of his pedipalps, which have a bulbous structure on the end, which you can clearly see. He then goes in search of a female. They approach each other face to face. The jaws are opened wide and locked together. The male jaw has a small hook which you can see where the fang starts, this is used to help hold the female's fangs. One slip and the male is dead, it seems that food takes precedence over mating.

Once the female is hooked, she automatically curls her abdomen forward, allowing the male to insert his seed, after which a hasty retreat is beaten.

I am not sure how the bulb structure works. I suspect it is some kind of injection thing. I haven't managed to find any more information on the structure, except from observation, the structure varies between different species.

The first time you see two spiders mating, it just looks like they are fighting, with lots of legs moving around, jostling for an advantage. But once you understand the procedure, it is much easier to see. This is the only time spiders get close to each other, so if you see two spiders within a couple of inches, it may be worth having a look for a few minutes to see what develops.

Adendum - The V shape is the chelicerae, the arms that hold the fangs. You can see the long curved fangs returning down the middle. The chelicerae can move in all directions and during mating they open out into a T.

The eyes are two rows of 4 black dots. The mouth is on the other side, opposite the eyes.

I always forget, most people don't know what they are looking at, these things are so alien :)

Dave