Daddy Long Legs
Opiliones (Latin opilio, “shepherd”; formerly Phalangida) are an order of arachnids commonly known as harvestmen.
Particularly in North America, Opiliones are colloquially known by the name “daddy longlegs” or “granddaddy longlegs”, but this name is also used for two other unrelated arthropods: the crane fly (Tipulidae) and the cellar spider (Pholcidae). They are also referred to as “shepherd spiders” in reference to how their unusually long legs reminded observers of the ways that some European shepherds used stilts to better observe their wandering flocks from distance.
As of December 2011, over 6,500 species of harvestmen have been discovered worldwide,although the real number of extant species may exceed 10,000.The order Opiliones includes four suborders: Cyphophthalmi, Eupnoi, Dyspnoi, and Laniatores, and representatives of each can be found on every continent except Antarctica (with the exception of Dyspnoi, which is restricted to North America and Eurasia). Well-preserved fossils have been found in the 400-million-year-old Rhynie cherts of Scotland, which look surprisingly modern, indicating that their basic body plan appeared very early on, and, at least in some taxa, has changed little since that time. Their phylogenetic position within Arachnida is disputed: their closest relatives may be the mites (Acari) or the Novogenuata (the Scorpiones, Pseudoscorpiones and Solifugae). Although superficially similar to and often confused with spiders (order Araneae), Opiliones is a distinct order that is not closely related to spiders within Arachnida. They can be easily distinguished from even long-legged spiders by their fused body regions and single pair of eyes in the middle of their cephalothorax (spiders have an ‘abdomen’ that is separated from the cephalothorax by a constriction, as well as three to four pairs of eyes, usually around the margins of their cephalothorax).