Secret life of daddy longlegs amazes scientists

By Gary Raham
Nature Writer

While hiking the lush woodland parkways of North Carolina recently, I encountered an old childhood acquaintance sharing the trail: a daddy longlegs.

You've seen these spider relatives whose body is suspended improbably in a network of eight spindly legs. In fact, admit it: You may have pulled off a few of those legs as a child--either accidentally or by devilish design--only to see them lie twitching on the ground.

Daddy longlegs (a.k.a. harvestmen, shepherd spiders, and Grand daddy longlegs) avoid lots of predators by leaving a leg or two behind while they scramble out of harm's way. But have you ever considered how totally bizarre these creatures are? They put some movie aliens from outer space to shame.

Maybe they inspired H.G. Wells when he created the spindly Martian invaders in "War of the Worlds." The early English microscopist, Robert Hooke, included a picture of their strange, oddly sculptured body in his book "Micrographica" written in 1665. Unlike spiders, with either six or eight eyes, the daddy longlegs (a member of the order Opiliones) possesses two. They reminded Hooke of vertebrate eyes: "These eyes, to appearance, seem'd to be of the very same structure with that of larger binocular creatures, seeming to have a very smooth and very protuberant cornea, and in the midst of it to have a very black pupil, incompassed about with a kind of grey iris..." The creatures reminded Hooke of tiny shore crustaceans, and he referred to them as "air crabs."

If you smell something bad while handling a daddy longlegs, don't blame your hiking partner. These beasts mix up a chemical brew in glands near the eyes that travel down channels in their armor to the legs. They often brush the stinky solution onto potential predators. They have chewing mouthparts like spiders, but no venom glands, and are basically harmless to humans. A few South American species can pinch pretty hard with one pair of legs. Daddy longlegs have no silk glands like spiders, but male opilionids do have something their spider counterparts lack: a retractable penis.

It might be indiscreet to mention this facet of sexual anatomy, except that daddy longlegs hold the distinction - at least temporarily - of having the oldest fossilized genitalia of any terrestrial animal. These well-preserved remains, formally described in 2003, turned up in the Rynie chert of Scotland, a rich fossil site that is approximately 400 million years old.

Daddy longlegs might also qualify as sexual athletes of sorts. Researcher Arlan Edgar once observed a couple mate 29 times in two and a half hours. After mating, the male stands over the female using his legs like a cage so that other males can't intrude while the female deposits her eggs in various cracks and crevices in decaying wood. Stressed males may also move their bodies up and down quickly in a series of push-ups that may also be part of their courtship repertoire.

Daddy longlegs like disturbed habitat with a bit of moisture. In Colorado, you might be most apt to see these creatures wandering in gardens or among crops like corn, alfalfa, small grains, potatoes, cabbage, strawberries and apple orchards. They are one of the "good guys," consuming various pest arthropods like aphids, caterpillars, leafhoppers, beetle larvae, mites and small slugs. They are generalist eaters and will clean up a variety of organic debris. Their prey capture technique is worthy of a sci-fi creature. They surround a meal with their legs, and then come down on them like a pile driver to attack from above with their chewing mouthparts (chelicerae).

Sometimes, daddy longlegs come together in aggregations. Naturalist Sue Hubbell often found them socializing in her beehives. She describes her experiences in a delightful book called "Broadsides From the Other Orders" (Random House, 1993). Opilionid expert Arlan Edgar believes beehives provide the moist and sheltered habitat daddy longlegs find desirable. Aggregation may also provide defense against predators, as it does for flocks of starlings and other creatures. Chances are the predator will get one of the other guys in the crowd.

So, when the cable channel self-destructs and you can't get the sci-fi channel, search the garden and take another look at your childhood friends, the daddy longlegs. And (as you might have guessed) there is a web site that will answer most, if not all, your burning questions about these strange creatures: http://www.arachnology.org/Arachnology/Pages/Opilio_QandA.html#E.