Among Inspector Gadget's many strange features—teeth that fly around on their own (go, go gadget teeth) and a flower that pops out of his hat (go, go gadget flower) and of course gadget Spanish translation—it's his telescoping neck that seems to most defy conventional biology. But it'd be hard to argue that a super-long neck doesn't come in handy in a pinch.
Just ask the bizarre assassin spiders of Australia, South Africa, and Madagascar, with their craning necks and enormous jaws and general what-in-the-what-now appearance. These beauties (also known appropriately enough as pelican spiders) hunt other spiders, and by deploying their jaws out 90 degrees from their necks, they can impale prey, inject venom, and let them dangle there to die, all without getting bitten themselves. It's a bit like the school bully holding a nerd at arm's-length while the poor kid swings hopelessly at the air.
Now, spiders aren’t supposed to have necks, and in fact calling this a neck is a bit of a misnomer. The front bit of a spider is known as the cephalothorax, where you find its legs and mouthparts and eyes, and on top of that is a plate known as a carapace (these terms are a bit goofy so I'm going to keep calling it a neck for the sake of your brain, but now you know the score). So they don’t really have a head as we’d recognize it. But in the assassin spiders, that carapace has been extremely elongated into a kind of tube. The eyes and the jaws (scientifically known as chelicerae, so I’ll just keep calling them jaws if you don’t mind) sit up at the top. Perhaps most weirdly, though, the feeding mouthparts remain down at the base of the neck. So really they have necks in the middle of their faces.
This all makes the assassin spiders somewhat … ungainly. Indeed, they tend to spend nearly all their time hanging upside down on leaves and such, and “it’s almost awkward for them to walk upright,” said arachnologist Hannah Wood of the University of California, Davis. “They're a little bit top-heavy, especially the species with the longest necks.” But Wood reckons that instead of their weird bodies long ago encouraging them to walk upside down, “it might be that since they all were upside down, that allowed for some of the necks to get really, really long, longer than if they were constrained walking upright.”
This is not to say that these spiders are anything short of master hunters. They’re the stealthy ninjas of the forest, feeling around for other spiders’ silk droplines with their elongated front legs, which function almost like antennae (they never build their own webs, by the way—they’re nomads). Once they’ve got a lead, they move gingerly toward the web so as to not arouse the suspicion of their prey. As they get closer, they pause at the edge of the web, or drop down on top of it with a silk line like Batman and whatnot. “It’s all very, very slow,” said Wood. “And I think it’s such a slow movement that their prey probably doesn't register that it’s another spider that’s coming to attack them.”
They’ll then begin plucking at the web with those elongated front legs, all the while constantly feeling around for their target (they’re unlikely to use vision at this point, because their two biggest eyes are situated almost on the sides of their heads). The dupe comes to investigate, and the assassin strikes, firing those jaws from their tucked-in resting position to 90 degrees and lunging to impale the poor critter (think of it like a forklift, but instead of lifting something gently with the forks the spider is just murdering it). Fangs at the tips of the jaws inject venom, as the assassin holds its prey well away from its body. It would seem this bizarre body evolved, then, to keep the wounded spider from biting back. And in this way, the assassin spider can take on prey almost as big as itself.
Weirdly, as soon as the prey is impaled, the assassin lowers one of its jaws back to the resting position, leaving the other at 90 degrees. Why that is, Wood can’t say. Really, it seems like a good way for your meal to slip out of your grasp. But it probably has something to do with energy efficiency, and it usually doesn’t take long for the prey to perish anyway. After a while, the assassin spider will use those long legs to feel the prey to make sure it isn’t moving anymore, then lower the jaws back down, perfectly aligning the food at the tip with the mouthparts at the base of the neck. And then it’s feeding time.
Those crazy jaws aren’t just for hunting, though. They’re also sexy violins.
You see, when two assassin spiders love each other very much, they flirt by vibrating their abdomens. “And then they also have these little modified pair of legs called pedipalps, really close to the mouthparts,” Wood said. “And they have specialized hairs that they rub on the jaws, and they vibrate that really quickly and make sounds.” Then once they do decide to mate, they line up belly to belly, facing away from each other—on account of those big heads being in the way. The male will then use his pedipalps to grab a sperm bundle from his genital opening and place it in the female’s genital opening.
When she eventually lays her eggs, she carries the egg case on her leg, "and she kind of drags it around with her wherever she goes,” Wood said. “It almost looks like a fungus spore, with this little ball hanging beneath them.” Once the kiddos hatch, the family will actually hang out together for a few days, “and then the little babies just decide to wander off and start to hunt.”
And so the next generation of ninjas heads off into the world to terrorize their fellow spiders and maybe, just maybe, one day use their faces as violins. Go, go gadget face violin!
