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Daddy Long Legs

All Fun and Games Until Someone Loses a Leg – or Three

Daddy long legs
Illustrations by Adelaide Tyrol

There’s a fantastic song by folk singer Colm Gallagher called “Reel in the Flickering Light” about a daddy long legs who, after first making inquiries about the singer’s sister, woos a red carnation. Although the term “daddy long legs” can refer to three distinct groups of organisms, including crane flies and true spiders, it’s clear that the song, with its reference to the dancer’s “thin and wispy spindles,” is referring to harvestmen, arachnids in the order Opiliones.

It’s easy to imagine a harvestman “on his delicate legs of silver” dancing with his ladylove in the evening light. Daddy long legs (Opiliones) have just one body segment to which all eight spindly legs are attached; they look rather like heads with legs. In contrast, spiders have sturdier builds, with two major body segments: their cephalothorax with legs attached, and behind that their abdomen. And crane flies have three body segments and, with minor exceptions, have wings.

I can’t get too far into a daddy long legs conversation with my students before I’m informed of the legendary toxicity of their venom, and our good fortune that these arachnids’ fangs are just too small to penetrate human skin. For this myth to hold water, our leggy friends would require both venom and fangs to inject it into thin-skinned prey. Like spiders, daddy long legs do have fanglike mouthparts called “chelicerae” that are indeed comparatively short; however, no one has found venom glands in any daddy long legs.

So what do daddy long legs do with their fangs? It seems like a simple question, but with more than 225 species in the United States alone, we might expect a bit of variability. Daddy long legs are opportunistic feeders. They happily dine on small invertebrates, alive or dead, and on decaying plant and fungal material. In one study, deceased earthworms were high on the menu. In a different study, a scientist offered pineapple and termites as alternative choices; most daddy long legs went for the pineapple, but a significant minority of them consumed termites, demonstrating their potential in pest control.

Daddy long legs are unusual among arachnids in that they can ingest solid food particles in addition to the more standard liquid fare. Spiders use their chelicerae to inject venom into prey and later to drain out their liquid meal, but daddy long legs use theirs to chew food. They also possess teeth on their chelicerae that they use for grooming.

And, other than sometimes stimulating arachnophobic responses, there is no evidence that your local daddy long legs population does harm of any sort to humans, crops, or favorite garden plants. In fact, because they dine on soft-bodied invertebrates such as aphids, they are likely a valuable addition to your farm or garden.

The most distinctive feature of daddy long legs is, of course, those very long legs – which are not actually used to keep the animal aloft. Rather, the legs arc up from the body and back down to the ground so that the body is usually in contact with the ground. This arrangement helps the daddy long legs to avoid desiccation, taking advantage of humid microhabitats between rocks and in tree bark furrows. The tarsus, or foot end of the leg, has all of the multi-joint flexibility of a bicycle chain, serving these arachnids very well when climbing and maneuvering over rough terrain.

Unfortunately, having stilt-like legs provides a convenient grip for birds and other predators. Daddy long legs have a strategy that gives them a leg up in this scenario: When a predator grabs a leg, the daddy long legs can pinch off the leg where it joins its body and beat a hasty retreat. The strategy is called “autotomy” or “self-amputation.” It leaves the predator with a distracting, still-twitching leg in its grasp while the daddy long legs lives to fight another day. And apparently it’s common; in one study, nearly half of the 1,000-plus daddy long legs examined were missing at least one leg.

Not surprisingly, losing a leg comes at a cost. Cary Cuffey from Our Lady of the Lake University in Texas studied mobility and feeding in daddy long legs. He found that losing a leg or two had little effect on speed and foraging success, but losing a third leg slowed the animals down by as much as two-thirds and limited their ability to find food.

It also matters which leg is lost. There is evidence that the second pair of legs function like the antennae of insects and are important for sensing food, predators, and mates in the environment. Daddy long legs that lost their second pair of legs were less likely to move, feed, or mate. It seems that that particular pair of legs would be essential for the character in the song to woo a mate, be that a flower, or one of its own species.

Discussion *

Dec 01, 2021

Super article. So interesting to learn more about this common yet cool insect.

Margie M.

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