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www.thevillagenews.co.za
1 July 2020
MY ENVIRONMENT
Face mites – we all have them! By Anina Lee
affecting the lids and lashes. Demodex folliculorum mites are wormlike, with eight stumpy legs; they are microscopic in size, measuring about 0.3 millimetres in length. They live near the roots of facial hair follicles, hidden away inside your pores.
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ace mites live in your pores, eat your grease and crawl on your face while you sleep. That’s right – they crawl out of your pores at night and party on your face. And you don’t even know it. You probably have a few dozen tiny arachnids on the shafts of hair on your face, quietly gorging themselves on your natural oils. There are two species of face mite called Demodex. They have eight legs, so they belong to the class Arachnida. They live within the hair follicles on human skin, feeding on face oils and dead skin cells. These mites tend to be most prevalent around the eyes,
There they have easy access to your sebum — the waxy oil your face secretes to keep hydrated. Sebum is produced by glands inside your pores, near the bottom of your hair follicles. Demodex mites love this greasy meal. They burrow face-first into your pores, gorge on your face oil and then at night, when you're asleep, they crawl out on your face to mate. That's right — there's a nightly mite party on your face, and you're not invited. You are but a sleeping partner. The entire lifecycle of Demodex. folliculorum lasts only 14–16 days. Adult mites copulate at the top of the hair follicle, near the skin surface. Eggs are deposited in the sebaceous (oil) gland inside the hair follicle. The heartshaped egg hatches into a six-legged larva. It takes seven days for the larva to develop into a mature 8-legged adult, which lives for only 4–6 days. Demodex mites pose no known threats to humans – that is unless they over-proliferate. Most people live peacefully with their face mites until old age. Just think, in your lifetime, your nose could serve as the family home to hundreds of generations of grease-swilling, nocturnal-partying arachnids. However, you probably won't ever
have to clean up after your Demodex houseguests. Face mites have no anus, instead storing their poop in their bodies for the full duration of their brief lives. Now that's just good manners. Michelle Trautwein, an evolutionary biologist at the California Academy of Sciences, thinks they're “actually pretty adorable." She believes the mites could help answer questions about human migrations through history, perhaps more than genetics or archaeology alone could because of how they're shared among humans.
ABOVE: Demodex folliculorum mites (above, much magnified) are worm-like, with eight stumpy legs and measure about 0.3 millimetres in length. They live near the roots of facial hair follicles, hidden away inside your pores. BELOW: Demodex folliculorum mite on the skin.
Mites are mostly shared between members of the same nuclear family. Because of that tight bond, the mites can be a pretty good measure of where people came from. The researchers collected mites from the faces of about 70 people with different origins, most of them now living in the US, and sequenced the mites' mitochondrial DNA. They found that people from different continents harbour different varieties of mites on their faces. Even generations after a family leaves one geographic region for another, their descendants can retain those original mite populations. "Basically, as all humans evolved in Africa, our mites evolved with us," says Trautwein. "And as mite populations became isolated they evolved into their own lineages, just like humans did." Think of them not as parasites, but as family heirlooms, your own special heritage. Friends forever.
RIGHT: This micrograph shows three Demodex folliculorum diving into a follicle next to a hair.
CIRCLE: Only a biologist would describe these microscopic arachnids as “actually pretty adorable”!
