Most of us think that daddy longlegs are spiders, but although they’re arachnids – like spiders, ticks, and scorpions – and they’re leggy (“longlegs”) like many spiders, they’re in a scientific order of their own. They are Opiliones.
Opiliones have a single pair of eyes, unlike spiders who may have 3 or 4 pairs, and they have a fused body – they don’t have a spider’s separated abdomen and cephalothorax.
Daddy longlegs are more formally known as “harvestmen”. Like spiders, harvestmen must molt as they grow. Their hard exoskeletons, or skins, don’t stretch or grow larger, so every growing harvestman must shed its skin periodically and replace it with a fresh, slightly bigger one.
We used to have about a zillion harvestmen here; these days there are not so many. They would huddle together in big clumps of dozens – or perhaps hundreds – up under the eaves during the day, quietly jiggling en masse. The huddles would disperse every evening when the harvestmen headed off to hunt for some supper and then recoalesce in the same spot by sunrise the next morning.
When I first arrived in Texas, I asked Dan why harvestmen huddled together in groups and he responded, mysteriously, “I can see why they huddle, but I don’t know why they jiggle”. I remain none the wiser.
NOTE: We thank local naturalist Sheryl Smith-Rodgers (www.sherylsmithrodgers.com) for telling us what was going on in this video. Dan and I thought we were seeing a new harvestman hatching, but Sheryl set us right; it’s molting.
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