The first-ever complete DNA analysis of the mites that live in our hair follicles reveals some peculiar body features and even more remarkable mating habits.

The hair follicle mite (Demodex folliculorum) is a mite that occurs in humans in hair follicles and sebaceous glands, especially on the face (eyebrows and around the nose). It is known that the mite sometimes walks over our face at night. But what he is up to there has been less known until now. Scientists have now sequenced the genome of these tiny critters. And their studies provides new (and a little creepy) insight into the secret life of the mites that inhabit our faces.

More about the hair follicle mite
There is a good chance that you also carry the hair follicle mite with you. The mite is passed on during birth and almost every human being on earth lives with it. The organisms have four pairs of short legs and are about 0.3 mm long. As mentioned, they are mainly in the hair follicles on our face – including the eyelashes – and feast on the sebum that naturally comes out of our pores. The mites are mainly active at night and move between the hair follicles to mate – more on that later.

To learn more about the hair follicle mite, researchers decided to study the mite’s DNA. And that leads to some remarkable discoveries. “We found that these mites have a different arrangement of genes than other similar species,” explains study leader Alejandra Perotti. “That’s probably because they’ve adapted to a sheltered life in the pores. These changes in their DNA have led to some unusual body characteristics and behavior.”

Simple Organisms

The critters have a very isolated existence. This is mainly because they have no natural enemies, do not suffer from competition and do not meet other mites with different genes. This has resulted in their genome being reduced to only the bare essentials. They are extremely simple organisms, with tiny legs powered by only three single-celled muscles. In addition, their bodies have the absolute minimum amount of protein, only what is needed for survival. It is the smallest number ever seen in this or related species.

night owls

This gene reduction is also the reason for the fact that the mites are real night owls. The mites are not equipped with UV protection and have lost the gene that causes animals to wake up in daylight. In addition, the mites are also unable to produce melatonin – a substance that makes small invertebrates active at night. However, that does not stop the hair follicle mite; it harvests the melatonin that is secreted by our skin during twilight.

Sex

Oh, and another fact you might not want to know: the mites have sex in your pores at night. And that is quite strange. The unique arrangement of genes has resulted in the hair follicle mite having some unusual mating habits. Unlike other mites, the reproductive organs of the hair follicle mite are in the front. Thus, the penis of the males sits at the front of the body and points upwards, which means that they have to position themselves below the female during mating. Then they have sex while both clinging to a human hair.

The picture shows the unusual position of the hair follicle mite’s penis. Image: University of Reading

You may be wondering what the benefit of these mites is and why they are allowed to live on our faces. The researchers have a suspicion.

Anus

It was previously suggested that the hair follicle mite does not have an anus and accumulates its feces throughout its life. These are then released only when the mite dies, causing skin inflammation. However, the new study shows that the mite does have an anus and is therefore wrongly blamed for many skin conditions. “Mites are blamed for many things,” says researcher Henk Braig. “But because they have lived with people for so long, they could also play a simple but important and beneficial role, for example by keeping the pores in our face open.”

All in all, the researchers reveal some bizarre features and properties of the mites that hide in our pores. However, it is doubtful whether the hair follicle mite has a long life. Their gene pool is very small and due to a lack of mates, their genetic diversity is likely to continue to decline. This means that the mites may be heading for an evolutionary dead end and may even become extinct.