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Wisconsin Natural Resources magazine

Wisconsin Natural Resources magazine

June 2000

The Big Daddy: Its legs can be 30 times longer than its body. © Don Blegen
The Big Daddy: Its legs can be 30 times longer than its body.

© Don Blegen


The elegant harvestmen are neither spiders nor insects.

Anita Carpenter

They seem to be everywhere: climbing over raspberry bushes and woodpiles, loping along woodland paths, or resting on cabin walls. With each trip outdoors we are likely to encounter these creatures that resemble split peas supported on eight long stilts. The gangly, fast-moving creatures are instantly recognized as daddy long-legs.

Although they resemble spiders, daddy long-legs, more correctly called "harvestmen," are neither spiders nor insects. Taxonomically, they are arthropods, in the same class as spiders, Arachnida, but in a different order, Phalangida. Anatomically daddy long-legs differ from spiders because their three body segments – head, thorax and abdomen, are joined as one compact body segment. Spiders have two body segments – the head and thorax are joined as the cephalothorax, and the abdomen is the second body segment. Insects, which are taxonomically in the class Insecta, have three distinct body segments.

Let daddy long-legs crawl onto your hand. It won't bite and you probably won't even feel it unless its second pair of legs is gently touching and exploring your hand. Take a closer look. The tiny black dot on top of its body is a raised knob or tubercle with two minute black eyes peering out. The body supports six pairs of appendages, the chelicerae, pedipalps and four pairs of legs. The chelicerae or jaws, and the short leg-like pedipalps are used for sensing, capturing and holding food until it is eaten.

The daddy long-legs' most impressive feature is its four pairs of long slender legs, which may be up to 30 times as long as its body. Each leg has seven segments and curves out at the tip. If the daddy long-legs is in danger of being caught, it can break off a portion of its legs and then escape while the detached legs continue to quiver in front of a confounded predator. Daddy long-legs can grow new legs to replace the broken ones.

That's not to diminish the value of those magnificent legs. They are so important that daddy long-legs spends considerable time fastidiously cleaning them. Each leg is gingerly held in its jaws and nibbled to clean the leg as it is carefully pulled through the chelicerae.

Adults ordinarily hide during the day and become active at twilight when they wander in search of food such as dead insects, plant juices and possibly living insects. When they walk, their bodies are always held a little distance above ground. As they move, seemingly on tiptoe, the second pair of legs, the longest, touch the surface sensing food. If something edible is detected, the daddy long-legs begins a teetering motion and tilts the body forward, enabling it to see over its legs and explore the intended object with its pedipalps. If the detected item is acceptable, the daddy long-legs grabs it with its pedipalps and eats it.

The more brilliantly colored males are smaller than females, but may have longer legs.

During the summer mating season, there is no formal courtship. The male simply climbs on the body of the female and transfers his spermatozoa into her gonopore. In autumn, the female uses a long, reversible ovipositor to deposit eggs into soil or crevices in wood. In Wisconsin, the adults most like1y die in autumn, thus the species overwinters in the egg stage. The young hatch the following spring and grow by splitting and shedding their "skins".

Next time you are startled by a daddy long-legs scurrying across the woodpile, spare its life, for it is a beneficial and graceful creature in the complex web of life.

Anita Carpenter keeps a close watch on nature's doings near her Oshkosh home.