Opiliones

Cyphophthalmi
Eupnoi
Dyspnoi
Laniatores

The Phalangids (legacy name) or Opiliones (better known as daddy long-legs or harvestmen) are eight-legged invertebrate animals belonging to the order Opiliones in the class Arachnida, in the subphylum Chelicerata of the phylum Arthropoda. As of 2006, over 6,400 species of Phalangids have been discovered worldwide. The order Opiliones can be divided in four suborders: Cyphophthalmi (Simon, 1879), Eupnoi (Hansen & Sørensen, 1904), Dyspnoi (Hansen & Sørensen, 1904) and Laniatores (Thorell, 1876). Well-preserved fossils have been found in the 400-million year old Rhynie cherts of Scotland, which look surprisingly modern, indicating that the basic structure of the harvestmen hasn't changed much since then. Phylogenetic position is disputed: their closest relatives may be the mites (Acari) or the Novogenuata.

In some places Harvestmen are known by the name "daddy longlegs" or "granddaddy longlegs", but this name can also refer to two other unrelated arthropods: the crane fly (Tipulidae) and the cellar spider (Pholcidae).