Opiliones

Opiliones Temporal range: Devonian – Recent
Hadrobunus grandis
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Class:	Arachnida
Subclass:	Dromopoda
Order:	Opiliones Sundevall 1833
Diversity
4 suborders, > 6,400 species

Harvestmen are eight-legged arachnids. Even though they are arachnids like spiders, harvestmen are not spiders. They are in the order Opiliones.

More than 6,400 species of harvestmen have been discovered, although the real number of extant species may be more than 10,000.^[1] Well-preserved fossils have been found in the 400-million year old Rhynie cherts of Scotland. Fossil harvestmen look surprisingly similar to modern harvestmen. Apparently, the basic body shape of harvestmen has not changed much.

In some places, harvestmen are known by the name "daddy longlegs", but this name is also used for two other unrelated arthropods: the crane fly (Tipulidae) and the cellar spider (Pholcidae).

Many species of harvestmen are omnivores--they eat anything they can find. Most of the time this is small insects, and some plants and fungi. Some are scavengers.

Harvestmen are not dangerous to humans. None of the described species have poison glands. They are not "true" spiders even though they look like spiders in many ways. For example, harvestmen have no venom or silk glands; spiders have these.

1. ↑ Pinto-da-Rocha R. Machado G. & Giribet G. eds. 2007. Harvestmen – The biology of Opiliones. Harvard University Press ISBN 0-674-02343-9