Some National Geographic grantees are braving the nighttime jungle of Costa Rica to catch gigantic whip spiders by hand, glue transmitters on their backs and paint them with nail polish.
Whip spiders are not actually spiders, but it's almost not worth splitting hairs with an arthropod like this. They're huge, first of all, with specially-adapted front legs that extend up to two feet long and move like whips (hence the name). They also possess delightful extra appendages called pedipalps, that are described as being like serrated blades.
The scientists are interested in whip spiders in particular because they have a strong sense of direction, almost like homing pigeons. Once the spiders are tagged, the team moves them several meters from their territory, which is usually a small area on the trunk of a tree. When the researchers return a few days later, they inevitably find the spider back in the same spot they captured it. Somehow the arachnid always finds its way back to its little patch of home turf.
But if they coat the spider's legs with nail polish, which blocks its ability to smell and touch, it can no longer navigate home—leaving the researchers with no doubt as to the origin of the spider's homing ability. (Before you call PETA, bear in mind that both the polish and the transmitter are shed the next time the spider molts, so it is only temporarily incapacitated.)
Says Verner Bingman, the project's leader, "It's really, really exciting to look at how a true kind of navigational system can evolve with the relatively simple nervous system that these guys have." That's true, and the specialized skills of arachnids and their relative intelligence to other arthropods is consistently fascinating. But all the same, I'm okay with staying far, far away from these little monsters.