Wild Thing : Harvestmen
Daddylonglegs often pulsate in large groups and emit an odd smell when threatened.
By Sheryl Smith-Rodgers
Huddled together in huge masses, daddylonglegs wobble and pulsate together with little provocation under limestone cliffs and roof eaves. Flip over a rock, and several may scamper out at top speed.
Are they spiders? Bugs? Nope. Biologists classify those strange-looking critters as harvestmen (Leiobunum townsendi), so named for their abundant numbers at harvest time. Like other arachnids, they have eight legs. But unlike spiders, harvestmen lack fangs, venom and silk-making spinnerets. They also have one globular body; spiders have two sections whereas insects have three.
Some species have extra long legs. Others run around on short, stubby ones. Nocturnal, harvestmen live under rocks and logs, in caves, and other sheltered areas, and sometimes inside homes. Scavengers by nature, they eat nearly anything, including worms, snails, small bugs, dead matter and plants. A tiny pair of eyes mounted atop their body allows them to see what's above them.
Completely harmless, harvestmen can release an unpleasant smell when threatened. If caught, one may lose a leg, which can twitch several minutes while the harvestman gets away. As for those throbbing masses, no one's sure why they do that. Perhaps they prefer to rest communally. Or maybe they can scare off predators better, especially when they all bounce up and down together.
FYI: Some folks also call cellar spiders and adult crane flies by the same name - daddylonglegs.