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Arachnids May Be Closer Than You Think | By Ranger Doug Sousa

May contain: animal, invertebrate, and spider

 Valley Wilds Article 

Many people have a fear of arachnids. Some think of a spider hanging delicately from a single thread inching down closer and closer to their sleeping mouth. Others fear a scorpion that has made a resting spot out of a shoe and would gladly defend itself against encroaching toes. Others yet fear a tick that hitches a ride on a blade of grass, makes its way to your skin, and buries its head in for a delightful meal before you have ever noticed it was there. Arachnids can make people feel squeamish or in some cases, outright disgusted. Even as a park ranger that loves the outdoors, I can tell you that it is very difficult for me to overcome my fear of spiders. Just watching a harmless Tarantula move across the ground, I can feel my face contort into a sneer with every one of its slow methodical steps.

So, what if I told you we have nothing to fear? That we shouldn’t avoid arachnids or fear them because arachnids are always with us and always have been? In fact, we humans, every one of us, have microscopic arachnids that live on our faces. Yep, it’s true. These microscopic monsters are called Demodex Mites. These mites burrow into our pores and eat the grease we produce on our faces. Now, there is no need to rush off to a mirror to see if I’m telling you the truth. They are much too small to see with the naked eye but trust me they are there. Species of Demodex Mites can be found on every mammal on planet Earth except for the Platypus and its egg-laying kin. In fact, the poor Field Mouse has four different species of mites that call its face home.

We humans actually aren’t home to one species of microscopic face spiders, but two. The Demodex folliculorum is a longer and skinnier mite that lives closer to the surface of the skin while our other friend, the Demodex brevis is shorter and wider and lives deeper in the pores. One would think that these two mite species that share the same host would be closely related. It turns out that they are not. Under closer study, it was revealed that D. brevis was more closely related to dog mites than its neighbor D. folliculorum.

It is unknown, however, how we got them. Some surmise that they have always been with us since we evolved from fur bearing creatures and that our mites evolved with us. Others believe that we may have picked them up when we domesticated animals. Possibly our affinity for dogs, cats, or livestock brought us these little gifts. Some others think that it could be both. They believe that D. folliculorum is our native mite and that we were introduced to D. brevis when we brought home man’s best friend. Though these are all possible, their origins are still a mystery.

Even though their origins are mysterious, they can help tell us something about our own past. We can look back at early humans and see their Demodex Mites. While D. folliculorum populations are like one another everywhere on Earth, it is believed that D. brevis mites may be genetically different depending on where you are from. Currently samples have only been taken from the United States and China. With this information scientists discovered that roughly 40,000 years ago as East Asian and European populations diverged and spread out from one another, their D. brevis mites did as well. Some think that the deeper burrowing habits of the D. brevis mean that they are shared among people less frequently as their D. folliculorum neighbors.

So, remember the next time you look at a spider coming your way and recoil in disgust it’s probably not coming for you at all, it’s just coming by to visit its cousins that are living on your face.