Acari (Mites and ticks)

Acari are small arachnids (eight-legged arthropods) and span two large orders of arachnids, the Acariformes and the Parasitiformes. Superorder Parasitiformes consist of ticks and a variety of mites, while Acariformes comprise the most diverse group of mites.

Mites occupy a wide range of ecological niches. Most mites are less than 1 mm in length, and have a simple, unsegmented body plan. Because of their small size, they are easily overlooked. They occur in diverse habitats; some live in both fresh and salt water, many Oribatida mites are important decomposers, eat a wide variety of material including living and dead plant and fungal material, lichens and carrion, while others live on plants creating galls, while others are predators or parasites. Most species are harmless to humans, but a few are associated with allergies or may transmit diseases.

Parasitic mites can infect both animals and plants. Parasitic mites primarily consume blood, skin and keratin. Dust mites, feed mostly on dead skin and hair shed from humans instead of consuming them from the organism directly.

Source: Wikipedia