Mites: Subclass Acari
Mites are the ultimate colonizers. Their miniscule size has allowed them to occupy a wide range of ecological niches, from the soil, to plants, to the follicles on our skin. While we may think of mites as parasitic, for the most part they act as decomposers, living in the soil and amongst the leaf litter, recycling organic material back to the earth. These arachnids are one of the exceptions to the “8-legs” rule: many species of mites only have 6 legs when in their nymphal stages.
You’ll notice I labeled the mites as Subclass: Acari instead of using their order, and that’s because “mites,” as we know them, actually belong to three separate superorders: Parasitiformes (which also contains the order Ixodida, the ticks), Opilioacariformes and Acariformes. Recent phylogenetic research suggests that Parasitiformes are closely related to Pseudoscorpiones (see below!) while Acariformes are closely related to Solifugae (camel spiders, as we explored last week). This suggests that mites have evolved from multiple common ancestors, making some mites more closely related to other arachnids than they are to each other. Taxonomy is a wild and challenging world, my friends.
Acari Fun Fact! I mentioned above that mites have colonized all sorts of niches, including the human body. While the thought of mites living on you may want to make you bathe in pesticide, some human mites are commensalists, not parasites. This means that they benefit from a host without causing that host any harm. The best example? Eyelash mites. Microscopic mites that reside in the hair follicles of eyelashes and consume the natural oils and sebum produced by the pores around the follicle. These are largely beneficial mites, and eye doctors note that while eyelash mites may multiply when an infection is present, you should be more worried about the infection than the mites.