Ancient Opiliones

Harvestman, originally uploaded by eclectic echoes.

Not so long ago Chris at Catalogue of Organisms decided to devote the next few years of his life to sorting out the nomenclature of the long-legged harvestman, a task that he admitted was prone to make him

Run screaming in horror from the entire concept of Asian Gagrellinae and end up crouched into the fetal position and whimpering in the darkest recesses of the wet collection.

You gotta respect a man who can take on his deepest fears like that (either that or prepare to offer him round-the-clock in-house meds, nursing and security).

I can't offer much about the harvestmen, except the most basic tidbits. While harvestmen are arachnids like spiders, they are not spiders, but belong to a sister group (order Opiliones) of the spiders (order Arenea). The most immediate visible difference between harvestmen and true spiders is the appearance of the body: spiders have a clearly defined two part body form consisting of a cephalothorax and an abdomen separated by a "waist", while harvestmen have a body in which the two sections appear fused into one oval shape.

Contrary to popular myth, Harvestmen pose no danger to humans, not because they can't pierce human skin (which all but the largest species can't, but that's beside the point), but because they have no piercing "fangs" and no venom glands. In the image you can clearly see the chelicerae, which have no piercing structures, unlike the true spiders.

Last tidbit...the Opiliones are an ancient group and have left some interesting fossils, including a 400 million year old fossilized penis. The oldest penis second oldest known penis known in fact.

The current and previous record holders? The Ostracod.

Update: I was wrong about the current record holder for the oldest known male genitals... not 3 months after the 412 Myo fossil harvestman was documented, a 425Myo Ostracod was documented with well preserved male member.