Harvestman

Description:

Called "Daddy long-legs" in the U.S., where children get a kick out of letting them walk on their hands and arms. Thousands of species (Order Opiliones) worldwide on every continent but Antarctica. It's a myth that they are highly venomous, but have mouths too small to bite people.

Notes:

From Wikipedia:
Opiliones (formerly Phalangida) are an order of arachnids commonly known as harvestmen. 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 the 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).[3] 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).

From Encyclopedia of Life:
the order name 'Opiliones' comes from the Latin word 'opilio' meaning 'shepherd', because walking harvestmen resembled the European shepherds who used to walk on stilts for an improved view of their flock. It is omnivorous, feeding commonly on small insects, plant material and fungi. The first pair of appendages (chelicera) near the mouth collects the food items and passes them to the second pair of appendages (pedipalps) where they are held and crushed by microscopic claws at the end of the pedipalps. The food is chewed and ingested, rather than having the juices sucked out. The harvestman cannot live for long without water. Harvestmen are most commonly seen in autumn, particularly during harvesting time. They are often found on shady walls on the outside of buildings, where they cluster together in groups of up to 400. They rest flat on the walls with their legs entwined, which serves several possible functions. By gathering together, the harvestmen may be creating an area of desirable temperature and humidity, or making use of the collective repellent power of their smelly defence. It has also been suggested that these aggregations pulsate in order to appear more intimidating to their predators. Harvestmen mate by internal fertilisation, and females use their ovipositor to lay the already fertilised eggs into crevices in the soil. The eggs survive through the winter and hatch in spring.