Abstract/Summary

We carry them in our skin pores through our entire life, from birth to death. We offer them shelter and in return, they tidy-up our pores. We go on with our busy day life and they sleep. They wake up when we go to sleep and while we are deeply dreaming, they move around, visit other pores and mates, and reproduce. Despite being our ‘very own’ life companions, until recently, we knew very little about their struggle. Their miniaturised Bauplan is perfectly fit for life inside the pores of hair follicles and sebaceous glands. Perception of light is achieved by one of the smallest ‘eyes’ (photoreceptors) known to date, and movement and dispersal is accomplished by minute legs powered by just three unicellular-uninucleate muscle segments. With a unique arrangement of Hox genes, their reproductive organs allow them to mate and to deliver offspring inside the limited space offered by the pores. Unless they soon find a way out, genome erosion, on an evolutionary time scale, is leading them to a dead end, to extinction. They outbreed less and less: each of us has a unique population, started by a few colonisers, legacy of our moms when we were babies. This resulted in a mite species that presents the lowest number of protein genes. Yet, they manage to successfully carry on with their lives by synchronising with our lifestyles, and we hope they will keep doing it for the foreseeable future!