TheAcarina, orAcari, are themites andticks. They are anorder ofArachnids. Their fossil history goes back to theDevonian era.
Most acarines are tiny: less than amillimetre. Over 50,000 species have been described, but a million or more species may be living. The study of mites and ticks is calledacarology.[1]
Acarines live in practically everyhabitat, including aquatic (freshwater and sea water) and terrestrial.
They outnumber otherarthropods in the soil anddetritus. Many areparasitic, and they affect bothvertebrates andinvertebrates. Most parasitic forms are external parasites, while the free living forms are generallypredators and may even be used to control undesirable arthropods. Others help to break down forestlitter and dead organic matter such asskin cells. Still others areherbivorous and may damagecrops. Damage to crops is perhaps the most costly economic effect of mites, especially by the spider mites and their relatives, earth mites, thread-footed mites and the gall and rust mites.
Some parasitic forms affecthumans and othermammals, causing damage by their feeding, and can even bevectors of diseases such asscrub typhus andrickettsia. A well-known effect of mites on humans is as anallergen which stimulatesasthma. Predatory mites may be used inpest control and herbivorous mites used to attackweeds.
A positive contribution of the Acari is their normal functions inecosystems, especially their roles in the decomposer subsystem.[1]
Mites are a hugely successful group with a large number ofspecies. They are among the most diverse and successful of allinvertebrates, but because of their small size they go largely unnoticed. They have exploited manyhabitats. Many live freely in the soil or water, but there are also a large number of species that live as parasites on plants, animals, and some that feed on moulds (fungi).
Ticks areblood-sucking ectoparasites, mostly ofmammals andbirds. They wait on grass or bushes, and jump onto passing animals. A number of birds specialise in picking them off larger animals: theCattle Egret and theOxpecker for example. They are quite serious pests, and can be hard to get rid of. They are vectors, carrying diseases such asLyme disease.
↑1.01.1Walter D.E. & Proctor H.C. 1999.Mites: ecology, evolution and behaviour. University of New South Wales Press, Sydney and CABI, WallingfordISBN0-86840-529-9
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