Harvestmen: Lifespan, Facts & Types

Instructor: Sarah Friedl

Sarah has two Master's, one in Zoology and one in GIS, a Bachelor's in Biology, and has taught college level Physical Science and Biology.

Though often mistaken for their relatives, harvestmen are unique creatures that stand apart from the crowd. In this lesson we'll discuss what harvestmen are, some interesting things to know about them, and the different kinds that exist.

I'm Not a Spider!

One very common source of confusion in the animal world involves spiders and their relatives. For example, spiders and other arachnids, such as ticks, mites, and scorpions, are often confused for insects. Another misconception within the Arachnida class is between spiders and harvestmen. Sometimes called 'daddy long legs', these creatures are in a separate order from spiders, called Opiliones.

Spiders (top) have 8 eyes and 2 body segments, while harvestmen (bottom) have only two eyes and one body segment
harvestmen spider comparison

The confusion between the two is not unjustified since they do have some similarities. And from high above the ground, our eyes tend to see all round things with eight long legs as spiders. But harvestmen have some distinct anatomical differences that you can see if you look closely enough. First, they do not have a separate head region - it's just one fused body. Harvestmen also have only one pair of eyes, while most spiders have a whopping four. And finally, harvestmen do not have fangs, venom, or silk glands.

Biology & Facts

So now that you know what harvestmen aren't, let's talk about what they are. Harvestmen are numerous and widespread. There are over 6,600 species of harvestmen, and they can be found just about everywhere but Antarctica. They need humidity, so they thrive in environments like forests and caves. Their average body length is 5/16 of an inch, and their leg span can exceed half a foot! They are typically carnivorous and feed on insects, though they are also scavengers of dead insects and plant material.

Although they only live for about one year, harvestmen have been on Earth for hundreds of millions of years. Some species of harvestmen have been known to aggregate in large numbers, with the largest recorded aggregation being an incredible 70,000 individuals. Though they are generally solitary creatures, it's thought that this grouping behavior allows them to avoid drying out during the day time in dry climates.

Like other arachnids, harvestmen have to shed their skin or molt in order to grow. Though they have eyes, they don't see very well, so it is thought that scent and touch are more useful senses. Harvestmen produce chemicals to keep predators at bay. They also produce chemicals that are useful to humans, and we have been able to isolate over 60 chemical compounds from their secretions.

Harvestmen can also shed their legs or leave one behind in the event of an attack. In fact, that leg will stay behind and twitch, distracting whoever detached it, while the harvestman makes its escape in the other direction.

Types of Harvestmen

Armored harvestmen have a bit more body protection than other types
armored harvestman

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