by Joseph DeSisto
I mostly work on centipedes. I like all sorts of creatures though, and one of my favorite groups are the whip-spiders, in the arachnid order Amblypygi. Amblypygids are distantly related to spiders, but look more like … well, they don’t look much like anything, except maybe a cross between a spider and an especially grotesque praying mantis.
Recently I’ve been teaching myself to identify the whip-spiders of the Americas. I’ve looked at quite a few now, and it turns out I love them. Here are some reasons why.
1) Grabby claws of death. Whip-spiders, like all arachnids, have pedipalps at the front of their body, which are sort of like short legs. These are an arachnid’s “hands,” and they can do all sorts of things. Spiders use theirs to manipulate prey, as well as in reproduction. A scorpion’s pedipalps are its pincers.
A whip-spider’s pedipalps are specialized too, but are less like pincers and more like medieval torture devices. They look sort of like a praying mantis’s front legs, but meaner. These claws might be several times longer than the whip-spider’s body, and can quickly swing forth to snatch an unsuspecting insect meal, draw it close, and finish with an appetizing crunch.
2) Legs that are antennae. Arachnids don’t have antennae. But a whip-spider’s front pair of legs, behind the grabby claws of death, are modified to serve this very purposes. These are the whip-spiders “whips,” and their main sensory devices. Since most species live in caves, they need to be able to navigate, capture prey, avoid predators, and reproduce all in complete darkness.
3) They live in families. Well, sort of — mothers care for their young, and the relationship can be long-lived. In a few species, whip spiders even stay with their mothers until they become adults (Rayor and Taylor 2006). This is almost unheard of in the arachnid world, where mothers may be just as likely to eat their grown-up young as care for them.
In these close family groups, whip-spiders identify each other using their sensitive whips. Aggression is very rare, although it can happen, especially if a member of another family comes too close (Walsh and Rayor 2008). When two unrelated whip-spiders meet, they raise their pedipalps high above their heads and threaten each other. If that doesn’t work, they do battle, swatting at each other like gladiators until one backs down.
There are many more reasons to find these creatures fascinating, but when it comes down to it, I love whip-spiders because they are just too strange — they should be aliens, or cartoon monsters. Whip spiders could be mythical creatures, but they aren’t. They really exist. That’s awesome.
Oh, and they fish … click here to read about that.
Rayor, L.S. and L.A. Taylor. Social behavior in amblypygids, and a reassessment of arachnid social patterns. Journal of Arachnology 34(2): 399-421.
Walsh, R.E. and L.S. Rayor. Kin discrimination in the amblypygid, Damon diadema. Journal of Arachnology 36(2): 336-343.