Opiliones are known by many names, shapes and sizes across the world. The harvestman (Opilion canestrinii) pictured here is typically found in Britain and Central Europe and closely resembles what are known as daddy longlegs in The United States.
Most people are familiar with some form of Opiliones, commonly known as daddy longlegs or harvestmen in North America and Europe. Perhaps just as common is the idea that they are among the most venomous spiders in the world, but their “fangs” are not strong enough to pierce human skin, leaving us immune to their threat.
Technically, Opiliones are arachnids, but they are classified in a distinctly different order and are actually considered to be more closely related to scorpions than spiders. They differ from spiders in a number of ways — while they do have eight legs, Opiliones only have one pair of eyes, do not produce silk, and most importantly, they do not have venom — those dagger like fangs you see are actually claws called chelicerae.
A harvestman (Pachyloidellus sp.) in Concón, Valparaíso Region, Chile. Photo credit:jovengandalf/Flickr (CC BY-SA 2.0)
There are believed to be several thousand species of Opiliones, which can be found in an array of body types all over the world. As recently as 2012, an unidentified species of harvestman was discovered in Laos with a leg span of 33 centimeters (more than 12 inches).
Often the target of cruel and bored children, another myth regarding Opiliones is that their long spindly legs will grow back after being pulled off — not true!
These creatures have an exoskeleton that does not regenerate like the tails of some lizards or the arms of a starfish. But in a bit of irony, one defense mechanism for certain species is autotomy, or self amputation, whereby the legs are discarded (and tend to twitch on their own once removed) to distract predators.
Another strange habit of some species and perhaps their most famous, is their affinity for clustering, which is believed to be a self defense tactic as well.