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Mites are small
arachnid Arachnida () is a class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytica ...

arachnid
s (eight-legged
arthropod An arthropod (, (gen. ποδός)) is an invertebrate animal having an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form the phylum Euarthropoda,Reference showing that Euarthropoda is a phylum: ...
s). Mites are not a defined taxon, but the name is used for members of several groups of the class
Arachnida Arachnida () is a class of joint-legged invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all animals apart fr ...

Arachnida
. Mites span two large orders of arachnids, the
Acariformes The Acariformes, also known as the Actinotrichida, are the most diverse of the two superorders of mite Mites are small arachnids (eight-legged arthropods). Mites are not a defined taxon, but the name is used for members of several groups of ...
and the
Parasitiformes Parasitiformes is an order of Acari (treated as a suborder and superorder in outdated classifications). An alternative name is Anactinotrichida. Parasitiformes is one of two groups (orders) in Acari, the other being Acariformes (Actinotrichida).E ...
, which were historically grouped together in the subclass Acari, but genetic evidence suggests are not closely related. The Parasitiformes include
ticks Ticks (suborder Ixodida) are parasitic arachnid Arachnida () is a Class (biology), class of joint-legged invertebrate animals (arthropods), in the subphylum Chelicerata. Arachnida includes orders containing spiders (the largest order), sco ...

ticks
, which are sometimes semantically distinguished from mites. Most mites are tiny, less than in length, and have a simple, unsegmented body plan. The small size of most species makes them easily overlooked; some species live in water, many live in soil as
decomposer Decomposers are Organism, organisms that break down dead or decaying organisms; they carry out decomposition, a process possible by only certain kingdoms, such as fungi. Like herbivores and predators, decomposers are heterotrophic, meaning that t ...
s, others live on plants, sometimes creating
gall Galls (from Latin ''galla'', 'oak-apple') or ''cecidia'' (from Greek ''kēkidion'', anything gushing out) are a kind of swelling growth on the external Tissue (biology), tissues of plants, fungi, or animals. Plant galls are abnormal outgrowths ...

gall
s, while others again are
predators Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common List of feeding behaviours, feeding behaviours that includes parasitism and micropredation (which ...

predators
or
parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), adapted structurally to this w ...

parasites
. This last type includes the commercially important ''
Varroa ''Varroa'' is a genus of parasitic Mesostigmata, mesostigmatan mites associated with honey bees, placed in its own family, Varroidae. The genus was named for Marcus Terentius Varro, a Roman scholar and beekeeper. The condition of a honeybee colon ...
'' parasite of
honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Eurasia. They are known for their construction of wiktionary:perennial, perennial Colony (biology), colonial nests from B ...

honey bee
s, as well as
scabies Scabies (also known as the seven-year itch) is a contagious skin infestation Infestation is the state of being invaded or overrun by pests Pest or The Pest may refer to: Science and medicine * Pest (organism), an animal or plant detrimenta ...

scabies
mites of humans. Most species are harmless to humans but a few are associated with allergies or may transmit diseases. The scientific discipline devoted to the study of mites is called
acarology Acarology (from Ancient Greek /, , a type of mite; and , -logy, ) is the study of mites and ticks, the animals in the order (biology), order Mite, Acarina. It is a subfield of arachnology, a subdiscipline of the field of zoology. A zoologist specia ...
.


Evolution and taxonomy

The mites are not a defined taxon, but is used for two distinct groups of arachnids, the
Acariformes The Acariformes, also known as the Actinotrichida, are the most diverse of the two superorders of mite Mites are small arachnids (eight-legged arthropods). Mites are not a defined taxon, but the name is used for members of several groups of ...
and the
Parasitiformes Parasitiformes is an order of Acari (treated as a suborder and superorder in outdated classifications). An alternative name is Anactinotrichida. Parasitiformes is one of two groups (orders) in Acari, the other being Acariformes (Actinotrichida).E ...
. The
phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram A diagram is a symbolic representation Representation may refer to: Law a ...

phylogeny
of the Acari has been relatively little studied, but molecular information from
ribosomal DNA Ribosomal DNA (rDNA) is a DNA Deoxyribonucleic acid (; DNA) is a molecule A scanning tunneling microscopy image of pentacene molecules, which consist of linear chains of five carbon rings. A molecule is an electrically Elec ...
is being extensively used to understand relationships between groups. The 18 S rRNA gene provides information on relationships among phyla and superphyla, while the
ITS2 Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit Ribosomal DNA, rRNA genes in the chromosome or the corresponding Transcription (genetics), transcribed region in the polyci ...
, and the 18S ribosomal RNA and
28S ribosomal RNA 28S ribosomal RNA is the structural ribosomal RNA (rRNA) for the large subunit (LSU) of eukaryotic cytoplasmic ribosomes, and thus one of the basic components of all eukaryotic cells. It has a size of 25S in plants and 28S in mammals, hence the ...
genes, provide clues at deeper levels.


Taxonomy

The third edition (2009) of the standard textbook ''A Manual of Acarology'' uses a system of six
orders Orders is a surname In some cultures, a surname, family name, or last name is the portion of one's personal name 300px, First/given, middle and last/family/surname with John Fitzgerald Kennedy as example. This shows a structure typical f ...
, grouped into three superorders: * Superorder
Opilioacariformes Opilioacariformes is the smallest order (or superorder) of mite Mites are small arachnids (eight-legged arthropods). Mites are not a defined taxon, but the name is used for members of several groups in the subclass acari of the class arachn ...
– a small order of large mites that superficially resemble
harvestmen The Opiliones (formerly Phalangida) are an Order (biology), order of arachnids Common name, colloquially known as harvestmen, harvesters, or daddy longlegs. , over 6,650 species of harvestmen have been discovered worldwide, although the total nu ...

harvestmen
(
Opiliones The Opiliones (formerly Phalangida) are an order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, ...

Opiliones
), hence their name * Superorder
Parasitiformes Parasitiformes is an order of Acari (treated as a suborder and superorder in outdated classifications). An alternative name is Anactinotrichida. Parasitiformes is one of two groups (orders) in Acari, the other being Acariformes (Actinotrichida).E ...
– ticks and a variety of mites ** Holothyrida - small group of predatory mites native to former
Gondwana Gondwana () or Gondwanaland was a supercontinent In geology Geology (from the Ancient Greek γῆ, ''gē'' ("earth") and -λoγία, ''-logia'', ("study of", "discourse")) is an Earth science concerned with the solid Earth, the rock (ge ...

Gondwana
landmasses **
Ixodida Ticks (suborder Ixodida) are parasitic arachnid Arachnida () is a class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of in ...

Ixodida
– ticks **
Mesostigmata Mesostigmata is an order of mites belonging to the Parasitiformes. Unlike most members of that group, many of these mites are not parasitic but free-living and predatory. They can be recognized by the single pair of Spiracle (arthropods), spiracle ...
– a large order of predatory and parasitic mites *** Trigynaspida - large, diverse order *** Monogynaspida - diverse order of parasitic and predatory mites * Superorder
Acariformes The Acariformes, also known as the Actinotrichida, are the most diverse of the two superorders of mite Mites are small arachnids (eight-legged arthropods). Mites are not a defined taxon, but the name is used for members of several groups of ...
– the most diverse group of mites **
Trombidiformes The Trombidiformes are a large, diverse order of mite Mites are small arachnids (eight-legged arthropods). Mites are not a defined taxon, but the name is used for members of several groups in the subclass acari of the class arachnid, Arachn ...
– plant parasitic mites (spider mites, peacock mites, gall mites, red-legged earth mites, etc.), snout mites, chiggers, hair follicle mites, velvet mites, water mites, etc. *** Sphaerolichida - small order of mites containing two families ***
Prostigmata The Prostigmata is a suborder of mites belonging to the order Trombidiformes, which contains the "sucking" members of the "true mites" (Acariformes). Many species are notorious pest (organism), pests on plants. Well-known examples of prostigmata ...
- large order of sucking mites **
Sarcoptiformes The Sarcoptiformes are an order (biology), order of Acari comprising over 15,000 described species in around 230 families. Previously it was divided into two suborders, Oribatida and Astigmatina, but Oribatida has been promoted to an order, and A ...
*** Oribatida – oribatid mites, beetle mites, armored mites (also cryptostigmata) *** Astigmatina – stored product, fur, feather, dust, and human itch mites, etc. It has been subsequently argued that Opilioacariformes should be considered a subgroup of Parasitiformes, based on genetic evidence.


Fossil record

The mite fossil record is sparse, due to their small size and low preservation potential. The oldest fossils of acariform mites are from the
Rhynie Chert The Rhynie chert is a Lower Devonian Sedimentary rock, sedimentary deposit exhibiting extraordinary fossil detail or completeness (a Lagerstätte). It is exposed near the village of Rhynie, Aberdeenshire, Scotland; a second unit, the Windyfield ...

Rhynie Chert
, Scotland, which dates to the early
Devonian The Devonian ( ) is a geologic period and system of the Paleozoic The Paleozoic (or Palaeozoic) Era ( ; from the Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the H ...
, around 410 million years ago while the earliest fossils of Parasitiformes are known from
amber Amber is fossil A fossil (from Classical Latin Classical Latin is the form of Latin language Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communi ...

amber
specimens dating to the mid-
Cretaceous The Cretaceous ( ) is a geological period A geological period is one of the several subdivisions of geologic time enabling cross-referencing of rocks and geologic events from place to place. These periods form elements of a hierarchy of division ...

Cretaceous
, around 100 million years ago. Most fossil acarids are no older than the
Tertiary Tertiary ( ) is a widely used but obsolete term for the geologic period The geologic time scale (GTS) is a system of chronological dating that classifies Geology, geological strata (stratigraphy) in time. It is used by geologists, paleontology ...

Tertiary
(up to 65 ).


Phylogeny

Members of the superorders
Opilioacariformes Opilioacariformes is the smallest order (or superorder) of mite Mites are small arachnids (eight-legged arthropods). Mites are not a defined taxon, but the name is used for members of several groups in the subclass acari of the class arachn ...
and
Acariformes The Acariformes, also known as the Actinotrichida, are the most diverse of the two superorders of mite Mites are small arachnids (eight-legged arthropods). Mites are not a defined taxon, but the name is used for members of several groups of ...
(sometimes known as Actinotrichida) are mites, as well as some of the
Parasitiformes Parasitiformes is an order of Acari (treated as a suborder and superorder in outdated classifications). An alternative name is Anactinotrichida. Parasitiformes is one of two groups (orders) in Acari, the other being Acariformes (Actinotrichida).E ...
(sometimes known as Anactinotrichida). Recent genetic research has caused a change in the naming scheme, however, and recent publications have changed the superorder
Parasitiformes Parasitiformes is an order of Acari (treated as a suborder and superorder in outdated classifications). An alternative name is Anactinotrichida. Parasitiformes is one of two groups (orders) in Acari, the other being Acariformes (Actinotrichida).E ...
to an order. Other recent research has suggested that Acari is
polyphyletic A polyphyletic group or assemblage is a set of organisms, or other evolving elements, that have been grouped together based on characteristics that do not imply that they share a common ancestor that is not also the common ancestor of many othe ...
(of multiple origins), with ticks and spiders more closely related than ticks and mites. The cladogram is based on Dabert et al. 2010, which used molecular data. It shows the Acariformes
sister A sister is a woman A woman is an adult female Female (symbol: ♀) is the sex of an organism, or a part of an organism, that produces non-mobile ovum, ova (egg cells). Barring rare medical conditions, most female mammals, including fema ...
to the
Solifugae Solifugae is an order Order or ORDER or Orders may refer to: * Orderliness Orderliness is associated with other qualities such as cleanliness Cleanliness is both the abstract state of being clean and free from germs, dirt, trash, or waste, an ...

Solifugae
(camel spiders), while the Parasitiformes are sister to the
Pseudoscorpionida A pseudoscorpion, also known as a false scorpion or book scorpion, is an arachnid belonging to the order Pseudoscorpiones, also known as Pseudoscorpionida or Chelonethida. Pseudoscorpions are generally beneficial to humans since they prey on Tineo ...

Pseudoscorpionida
.


Anatomy


External

Mites are tiny members of the class
Arachnid Arachnida () is a class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of individuals or objects * Class (philosophy), an analytica ...

Arachnid
a; most are in the size range but some are larger and some are no bigger than as adults. The body plan has two
regions In geography Geography (from Greek: , ''geographia'', literally "earth description") is a field of science devoted to the study of the lands, features, inhabitants, and phenomena of the Earth and planets. The first person to use the wor ...
, a
cephalothorax The cephalothorax, also called prosoma in some groups, is a tagma of various arthropod An arthropod (, (gen. ποδός)) is an invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ...
(with no separate head) or prosoma, and an
opisthosoma The opisthosoma is the posterior part of the body in some arthropods, behind the prosoma (cephalothorax). It is a distinctive feature of the subphylum Chelicerata (arachnids, horseshoe crabs and others). Although it is similar in most respects to a ...
or abdomen. Segmentation has almost entirely been lost and the prosoma and opisthosoma are fused, only the positioning of the limbs indicating the location of the segments. At the front of the body is the
gnathosoma The gnathosoma (from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately 10.7 mi ...
or capitulum. This is not a head and does not contain the eyes or the brain, but is a retractable feeding apparatus consisting of the
chelicerae The chelicerae () are the mouthparts of the Chelicerata, an arthropod An arthropod (, (gen. ποδός)) is an invertebrate animal having an exoskeleton, a Segmentation (biology), segmented body, and paired jointed appendages. Arthropods form ...

chelicerae
, the
pedipalp Pedipalps (commonly shortened to palps or palpi) are the second pair of appendage An appendage (or outgrowth) is an external body part, or natural prolongation, that protrudes from an organism In biology, an organism () is any orga ...
s and the oral cavity. It is covered above by an extension of the body
carapace A carapace is a Dorsum (biology), dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tor ...
and is connected to the body by a flexible section of
cuticle A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non-homology (biology), homologous, differing in the ...
. The mouthparts differ between taxa depending on diet; in some species the appendages resemble legs while in others they are modified into chelicerae-like structures. The oral cavity connects posteriorly to the mouth and pharynx. Most mites have four pairs of legs, each with six segments, which may be modified for swimming or other purposes. The dorsal surface of the body is clad in hardened
tergites A tergum (Latin for "the back"; plural terga, associated adjective tergal) is the Anatomical terms of location#Dorsal and ventral, dorsal ('upper') portion of an arthropod segment other than the head. The Anatomical terms of location#Anterior and po ...
and the ventral surface by hardened
sclerite A sclerite (Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately ...
s; sometimes these form transverse ridges. The
gonopore A gonopore, sometimes called a gonadopore, is a genital pore in many invertebrates. Hexapoda, Hexapods, including insects have a single common gonopore, except mayfly, mayflies, which have a pair of gonopores. More specifically, in the unmodified ...
(genital opening) is located on the ventral surface between the fourth pair of legs. Some species have one to five median or lateral eyes but many species are blind, and slit and pit sense organs are common. Both body and limbs bear
seta In biology Biology is the natural science that studies life and living organisms, including their anatomy, physical structure, Biochemistry, chemical processes, Molecular biology, molecular interactions, Physiology, physiological mechanis ...

seta
e (bristles) which may be simple, flattened, club-shaped or sensory. Mites are usually some shade of brown, but some species are red, orange, black or green, or some combination of these colours.


Internal

Mite digestive systems have salivary glands that open into the preoral space rather than the foregut. Most species carry two to six pairs of salivary glands that empty at various points into the subcheliceral space. A few mite species lack an anus: they do not defecate during their short lives. The circulatory system consists of a network of sinuses and lacks a heart, movement of fluid being driven by the contraction of body muscles. Gas exchange is carried out across the body surface, but many species additionally have between one and four pairs of
trachea The trachea, also known as the windpipe, is a cartilaginous Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue, rubber-like padding that covers and protects the ends of long bone A bone is a Stiffness, rigid tissue ...

trachea
e, the spiracles being located in the front half of the body. The excretory system includes a
nephridium The nephridium (plural ''nephridia'') is an invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all animals apart fr ...
and one or two pairs of
Malpighian tubule The Malpighian tubule system is a type of excretory and osmoregulation, osmoregulatory system found in some insects, myriapods, arachnids and tardigrades. The system consists of branching tubules extending from the alimentary canal that absorbs ...
s.


Reproduction and life cycle

The sexes are separate in mites; males have a pair of
testes Testicle or testis (plural testes) is the male Male (symbol: ♂) is the sex of an organism that produces the gamete (sex cell) known as sperm, which fuses with the larger female gamete, or ovum, in the process of fertilization. A male or ...

testes
in the mid-region of the body, each connected to the gonopore by a
vas deferens The vas deferens, or ductus deferens, is part of the male reproductive system The male reproductive system consists of a number of sex organs that play a role in the process of human reproduction. These organs are located on the outside of the ...

vas deferens
, and in some species there is a chitinous
penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during Copulation (zoology), copulation. Such organs occur in many animals, both #Vertebrates, vertebrate ...

penis
; females have a single
ovary The ovary is an organ found in the female reproductive system The female reproductive system is made up of the internal and external sex organs that function in reproduction of new offspring. In humans, the female reproductive system is im ...

ovary
connected to the gonopore by an
oviduct The oviduct is the passageway in animals from an ovary The ovary is an organ found in the female reproductive system The female reproductive system is made up of the internal and external sex organs that function in reproduction of new of ...
, as well as a
seminal receptacle Female sperm storage is a biological process and often a type of sexual selection in which spermatozoa, sperm cells transferred to a female during mating are temporarily retained within a specific part of the reproductive tract before the oocyte, o ...
for the storage of
sperm Sperm is the male reproductive Cell (biology), cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as ...

sperm
. In most mites, sperm is transferred to the female indirectly; the male either deposits a
spermatophore A spermatophore or sperm ampulla is a capsule or mass containing spermatozoa A spermatozoon (pronounced , alternate spelling spermatozoön; plural spermatozoa; from grc, σπέρμα ("seed") and grc, ζῷον ("living being")) is a motile spe ...
on a surface from which it is picked up by the female, or he uses his chelicerae or third pair of legs to insert it into the female's gonopore. In some of the
Acariformes The Acariformes, also known as the Actinotrichida, are the most diverse of the two superorders of mite Mites are small arachnids (eight-legged arthropods). Mites are not a defined taxon, but the name is used for members of several groups of ...
, insemination is direct using the male's penis. The eggs are laid in the
substrate Substrate may refer to: Physical layers *Substrate (biology), the natural environment in which an organism lives, or the surface or medium on which an organism grows or is attached **Substrate (locomotion), the surface over which an organism loco ...
, or wherever the mite happens to live. They take up to six weeks to hatch, according to species, and the first stage larvae have six legs. After three moults, the larvae become nymphs, with eight legs, and after a further three moults, they become adults. Longevity varies between species, but the lifespan of mites is short as compared to many other arachnids.


Ecology


Niches

Mites occupy a wide range of
ecological niches In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Topics of interest include the biod ...
. For example, Oribatida mites are important
decomposers Decomposers are organisms that break down dead or decaying organisms, they carry out decomposition, a process possible by only certain kingdoms, such as fungi. Like herbivores and predator Predation is a biological interaction where one o ...
in many habitats. They eat a wide variety of material including living and dead plant and fungal material, lichens and carrion; some are
predatory Predation is a biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical envi ...

predatory
, though no oribatid mites are
parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...

parasitic
. Mites are among the most diverse and successful of all
invertebrate Invertebrates are animals that neither possess nor develop a vertebral column (commonly known as a ''backbone'' or ''spine''), derived from the notochord. This includes all animals apart from the chordata, chordate subphylum vertebrate, Vertebra ...
groups. They have exploited a wide array of
habitat In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, "study of") is the study of the relationships between living organisms, including humans, and their physical environment. Ecology considers at the ...
s, and because of their small size go largely unnoticed. They are found in fresh and salt water, in the soil, in forests, pastures, agricultural crops, ornamental plants, thermal springs and caves. They inhabit organic debris of all kinds and are extremely numerous in leaf litter. They feed on animals, plants and fungi and some are
parasites Parasitism is a Symbiosis, close relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), adapted structurally to this w ...

parasites
of plants and animals. Some 48,200 species of mites have been described, but there may be a million or more species as yet undescribed. The tropical species '' Archegozetes longisetosus'' is one of the strongest animals in the world, relative to its mass (100 μg): It lifts up to 1,182 times its own weight, over five times more than would be expected of such a minute animal. A mite also holds a speed record: for its length, '' Paratarsotomus macropalpis'' is the fastest animal on Earth.


Parasitism

Many mites are
parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...

parasitic
on plants and animals. One family of mites,
Pyroglyphidae Pyroglyphidae is a family of non-parasitic mites. It includes the house dust mite that live in human dwellings, many species that live in the burrows and nests of other animals, and some pests of dried products stored in humid conditions. Etymol ...
, or nest mites, live primarily in the nests of birds and other animals. These mites are largely
parasitic Parasitism is a Symbiosis, symbiotic biological interactions, relationship between species, where one organism, the parasite, lives on or inside another organism, the Host (biology), host, causing it some harm, and is adaptation (biology), ad ...

parasitic
and consume
blood Blood is a body fluid Body fluids, bodily fluids, or biofluids are liquid A liquid is a nearly incompressible In fluid mechanics or more generally continuum mechanics, incompressible flow (isochoric process, isochoric flow) refers t ...

blood
,
skin Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation. Other cuticle, animal coverings, such as the arthropod exoskeleton, have differ ...

skin
and
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin Alpha-keratin, or α-keratin, is a type of keratin Keratin () is one of a family of fibrous structural proteins known as Scleroprot ...

keratin
.
Dust mites House dust mites (HDM, or simply dust mites) are various species of Acariformes, acariform mites belonging to the family Pyroglyphidae that are found in association with dust in dwellings. They are known for causing an dust mite allergy, allergy. ...
, which feed mostly on dead skin and hair shed from humans instead of consuming them from the organism directly, evolved from these parasitic ancestors.
Ticks Ticks (suborder Ixodida) are parasitic arachnid Arachnida () is a class Class or The Class may refer to: Common uses not otherwise categorized * Class (biology), a taxonomic rank * Class (knowledge representation), a collection of in ...

Ticks
are a prominent group of mites that are parasitic on vetebrates, mostly mammal and birds, feeding on blood with specialised mouthparts. Parasitic mites sometimes infest insects. ''
Varroa destructor ''Varroa destructor'' (''Varroa'' mite) is an ectoparasite, external parasitic mite that attacks and feeds on the honey bees ''Apis cerana'' and ''Apis mellifera''. The disease caused by the mites is called varroosis. The ''Varroa'' mite can re ...

Varroa destructor
'' attaches to the body of
honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Eurasia. They are known for their construction of wiktionary:perennial, perennial Colony (biology), colonial nests from B ...

honey bee
s, and ''
Acarapis woodi ''Acarapis woodi'' is an internal parasite affecting honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Eurasia. They are known for their construction of wikti ...
'' (family Tarsonemidae) lives in their
trachea The trachea, also known as the windpipe, is a cartilaginous Cartilage (cartilaginous tissue) is a resilient and smooth elastic tissue, rubber-like padding that covers and protects the ends of long bone A bone is a Stiffness, rigid tissue ...
e. Hundreds of species are associated with other bees, mostly poorly described. They attach to bees in a variety of ways. For example, ''
Trigona corvina ''Trigona corvina'' (Cockerell, 1913) is a species of stingless bee that lives primarily in Central and South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relative ...

Trigona corvina
'' workers have been found with mites attached to the outer face of their hind tibiae. Some are thought to be parasites, while others are beneficial
symbionts Symbiosis (from Greek , , "living together", from , , "together", and , bíōsis, "living") is any type of a close and long-term biological interaction In ecology Ecology (from el, οἶκος, "house" and el, -λογία, label=none, ...

symbionts
. Mites also parasitize some ant species, such as ''
Eciton burchellii ''Eciton burchellii'' is a species of New World army ant in the genus ''Eciton''. This species performs expansive, organized swarm raids that give it the informal name, ''Eciton'' army ant. This species displays a high degree of worker polymorphi ...
''. Plant pests include the so-called
spider mite Spider mites are members of the Acari The Acari (or Acarina ) are a taxon of arachnids that contains mites and ticks. The diversity of the Acari is extraordinary and their fossil record, fossil history goes back to at least the early Devonia ...

spider mite
s (family
Tetranychidae Spider mites are members of the Acari (mite) family Tetranychidae, which includes about 1,200 species. They generally live on the undersides of leaf, leaves of plants, where they may spin protective silk Spider web, webs, and they can cause damage ...

Tetranychidae
), thread-footed mites (family Tarsonemidae), and the
gall mite Eriophyidae is a family of more than 200 genera of mites, which live as plant parasites, commonly causing galls or other damage to the plant tissues and hence known as gall mites. About 3,600 species have been described, but this is probably le ...
s (family
Eriophyidae Eriophyidae is a family of more than 200 genera of mites, which live as plant Plants are mainly multicellular organisms, predominantly photosynthetic Photosynthesis is a process used by plants and other organisms to Energy transfo ...
). Among the species that attack animals are members of the
sarcoptic mange Mange is a type of skin disease A skin condition, also known as cutaneous condition, is any medical condition A disease is a particular abnormal condition that negatively affects the structure or function (biology), function of all ...
mites (family
Sarcoptidae The Sarcoptidae family of mites contains the genus ''Sarcoptes''. Sarcoptic mange is caused by burrowing mites within this genus. References

Sarcoptiformes Acari families {{Sarcoptiformes-stub ...
), which burrow under the skin. Demodex mites (family Demodecidae) are parasites that live in or near the
hair follicle The hair follicle is an organ Organ may refer to: Biology * Organ (anatomy) An organ is a group of Tissue (biology), tissues with similar functions. Plant life and animal life rely on many organs that co-exist in organ systems. A given org ...

hair follicle
s of
mammal Mammals (from Latin Latin (, or , ) is a classical language A classical language is a language A language is a structured system of communication Communication (from Latin ''communicare'', meaning "to share" or "to be i ...
s, including humans.


Dispersal

Being unable to fly, mites need some other means of dispersal. On a small scale, walking is used to access other suitable locations in the immediate vicinity. Some species mount to a high point and adopt a dispersal posture and get carried away by the wind, while others waft a thread of silk aloft to balloon to a new position. Parasitic mites use their hosts to disperse, and spread from host to host by direct contact. Another strategy is
phoresy hitching a ride on a fly. File:Phoresy_edited.png, A pseudoscorpion on the leg of a crane fly Phoresis or phoresy is a non-permanent, Commensalism, commensalistic interaction in which one organism (a phoront or phoretic) attaches itself to anoth ...
; the mite, often equipped with suitable claspers or suckers, grips onto an insect or other animal, and gets transported to another place. A phoretic mite is just a hitch-hiker and does not feed during the time it is carried by its temporary host. These travelling mites are mostly species that reproduce rapidly and are quick to colonise new habitats.


Relationship with humans

Mites are tiny, almost invisible, and apart from those that are of economic concern to humans, little studied. The majority are beneficial, living in the soil or aqueous environments and assisting in the decomposition of decaying organic material, or consuming fungi, plant or animal matter, as part of the
carbon cycle The carbon cycle is the biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere, and Earth's atmosphere, atmosphere of the Earth. Carbon is the main component of biological compounds as well as ...

carbon cycle
.


Medical significance

The majority of mite species are harmless to humans and
domestic animal This page gives a list of domestic animals, also including a list of animals which are or may be currently undergoing the process of domestication and animals that have an extensive relationship with humans beyond simple predation. This includes s ...
s, but a few species can colonize mammals directly, acting as
vector Vector may refer to: Biology *Vector (epidemiology) In epidemiology Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and risk factor, determinants of health and disease conditions in defined pop ...
s for disease transmission, and causing or contributing to allergenic diseases. Mites which colonize human skin are the cause of several types of itchy skin rashes, such as
gamasoidosis Gamasoidosis or dermanyssosis is a frequently unrecognized Ectoparasitic infestation, ectoparasitosis and source of growing concern in human medicine, occurring after contact with avian mites which Infestation, infest Serinus, canaries, Old World ...
, rodent mite dermatitis, grain itch, grocer's itch, and
scabies Scabies (also known as the seven-year itch) is a contagious skin infestation Infestation is the state of being invaded or overrun by pests Pest or The Pest may refer to: Science and medicine * Pest (organism), an animal or plant detrimenta ...

scabies
; ''Sarcoptes scabiei'' is a parasitic mite responsible for scabies, which is one of the three most common skin disorders in children. ''Demodex'' mites, which are common cause of mange in dogs and other domesticated animals, have also been implicated in the human skin disease rosacea, although the mechanism by which ''demodex'' contributes to the disease is unclear. Ticks are well known for carrying diseases, such as Lyme disease and Rocky Mountain spotted fever. Chiggers are known primarily for their chigger bite, itchy bite, but they can also spread disease in some limited circumstances, such as scrub typhus. The house-mouse mite is the only known vector of the disease rickettsialpox. House dust mites, found in warm and humid places such as beds, cause several forms of allergic diseases, including hay fever, asthma and eczema, and are known to aggravate atopic dermatitis. Mites of domestic animals, Among domestic animals, sheep are affected by the mite ''Psoroptes ovis'' which lives on the skin, causing hypersensitivity and inflammation. Hay mites are a suspected reservoir for scrapie, a prion disease of sheep.


In beekeeping

The mite ''Varroa destructor'' is a serious pest of
honey bee A honey bee (also spelled honeybee) is a eusocial flying insect within the genus ''Apis'' of the bee clade, all native to Eurasia. They are known for their construction of wiktionary:perennial, perennial Colony (biology), colonial nests from B ...

honey bee
s, contributing to colony collapse disorder in beekeeping, commercial hives. This organism is an obligate external parasite, able to reproduce only in bee colonies. It directly weakens its host by sucking up the bee's fat, and can spread RNA viruses including deformed wing virus. Heavy infestation causes the death of a colony, generally over the winter. Since 2006, over 10 million beehives have been lost.


In culture

Mites were first observed under the microscope by the English polymath Robert Hooke. In his 1665 book ''Micrographia'', he stated that far from being spontaneously generated from dirt, they were "very prettily shap'd Insects". The world's first science documentary featured cheese mites, seen under the microscope; the short film was shown in London's Alhambra music hall in 1903, causing a boom in the sales of simple microscopes. A few years later, Arthur Conan Doyle wrote a satirical poem, ''Parable'', with the conceit of some cheese mites disputing the origin of the Truckle, round Cheddar cheese in which they all lived.


See also

* Grain itch * Grocer's itch * Copra itch * Gamasoidosis * Chigger bite * List of mites associated with cutaneous reactions


References


External links


Bitingmites.org: What's biting you?


* [http://entomology.ifas.ufl.edu/fasulo/vector/chapter_05.htm Mites and Ticks] chapter in United States Environmental Protection Agency and University of Florida/Institute of Food and Agricultural Sciences National Public Health Pesticide Applicator Training Manual * {{Acari Acari Paraphyletic groups Arthropod common names