Harvestmen

Seeing a mass of harvestmen (aka “daddy longlegs”) would probably cause panic for anyone suffering from arachnophobia. I was removing a bbq pit from an old shed and upon opening it found a throng of harvestmen that was so massive it covered the entire inner surface of the pit’s lid. Realizing they were exposed they all began bobbing up and down giving them an even more creepy appearance. A little known fact though is that harvestmen are actually not true spiders. They fall in the order Opiliones, whereas spiders are in the order Araneae. They have eight legs, but are different from spiders in other ways.


~ The bodies of spiders have two sections- the abdomen and cephalothorax. Harvestmen have an oval-shaped body much like mites and ticks. There are two parts fused together giving the appearance of a single segment with no "waist".

~ Spiders have venom with which they inject their prey to immobilize them, but harvestmen do not. They do have fang-like mouthparts (chelicerae) and feed on insect eggs, decaying plant matter, aphids, caterpillars, flies, mites, earthworms, snails, and any decaying animal matter they come across.

~ Spiders have silk producing glands; Harvestmen do not produce silk and in turn no webs.

Harvestmen do perform one feat not done by true spiders- if attacked by a predator they can detach a wriggling leg much like geckos and lizards do with their tail in order to distract it while the harvestman escapes (Note the missing leg in the photo above). This can be a blessing and a curse though. The ejected leg does not regenerate like the afformentioned tails meaning each time it loses a leg in order to escape being eaten it becomes progressively handicapped.

So all of you arachophobes remember these guys are harmless, not really spiders and are pretty much nothing but legs. There's an old French peasant legend that states "the sighting of a harvestman in the evening hours is a good omen, a portent of good luck, and a symbol of hope."

Sources:

Harvestmen: The Biology of Opiliones. Glauco Machado & Gouzalo Giribet. Harvard University Press (c) 2007.

http://en.wikipedia.org/wiki/Harvestman