Daddy longlegs: spider or not?

Almost everyone has walked on the patio or near the side of a house and spotted the spider with long legs and almost no body, with legs so spindly that they seem to be as thin as a hair. This is the well-known daddy-longlegs spider, also known as the harvestman. But wait a minute: is this eight-legged critter a spider at all?

The harvestman is an arachnid, but of the opilionid family, which is more closely related to ticks and mites than spiders. A close look at the harvestman reveals a pill-shaped single-body segment with the eight legs attached to that segment. A true spider has three main body segments: the head, thorax, and abdomen, with the legs attached to the thorax region.

The daddy longlegs also has the reputation of being very venomous, but has mouth parts too soft to administer a painful bite to a person. In reality, a harvestman does not have any venom or venom delivery system at all. The harvestman feeds mainly on decaying plant or animal matter, but will occasionally take very small insects.

The harvestman should not be confused with the celler spider, sometimes called the daddy-longlegs spider. This spider is of the pholcidae family and has the classic three-segment body mentioned above. The cellar spider is not known to bite humans.