58-407: Ascidae is a family of mites in the order Mesostigmata . Ascidae are mites characterised by: seta st4 usually on unsclerotised cuticle , peritrematic shield broadly connected to exopodal shield beside coxa IV, fixed cheliceral digit with setiform pilus dentilis and movable cheliceral digit usually with two teeth, sternal shield with three pairs of lyrifissures and the third pair usually on
116-425: A cephalothorax (with no separate head) or prosoma, and an opisthosoma 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 or capitulum. This is not a head and does not contain the eyes or the brain, but is a retractable feeding apparatus consisting of
174-408: A prion disease of sheep. The mite Varroa destructor is a serious pest of honey bees , contributing to colony collapse disorder in 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
232-447: A century earlier). The definition was posited because extinct organisms are hardest to classify: they can be offshoots that diverged from a phylum's line before the characters that define the modern phylum were all acquired. By Budd and Jensen's definition, a phylum is defined by a set of characters shared by all its living representatives. This approach brings some small problems—for instance, ancestral characters common to most members of
290-577: A colony, generally over the winter. Since 2006, more than 10 million beehives have been lost. Various mites prey on other invertebrates and can be used to control their populations. Phytoseiidae , especially members of Amblyseius , Metaseiulus , and Phytoseiulus , are used to control pests such as spider mites. Among the Laelapidae , Gaeolaelaps aculeifer and Stratiolaelaps scimitus are used to control fungus gnats , poultry red mites and various soil pests. Mites were first observed under
348-522: A few phylogenomic studies have found strong support for monophyly of Acari and a sister relationship between Acariformes and Parasitiformes, although this finding has been questioned, with other studies suggesting that this likely represents a long branch attraction artefact. Mites are tiny members of the class Arachnida ; most are in the size range 250 to 750 μm (0.01 to 0.03 in) but some are larger and some are no bigger than 100 μm (0.004 in) as adults. The body plan has two regions ,
406-477: A level of the Linnean hierarchy without referring to (evolutionary) relatedness is unsatisfactory, but a phenetic definition is useful when addressing questions of a morphological nature—such as how successful different body plans were. The most important objective measure in the above definitions is the "certain degree" that defines how different organisms need to be members of different phyla. The minimal requirement
464-439: 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. The mites living in soil consist of
522-765: A network of sinuses and most mites lacks a heart, movement of fluid being driven by the contraction of body muscles. But ticks, and some of the larger species of mites, have a dorsal, longitudinal heart. Gas exchange is carried out across the body surface, but many species additionally have between one and four pairs of tracheae . The excretory system includes a nephridium and one or two pairs of Malpighian tubules . Several families of mites, such as Tetranychidae, Eriophyidae, Camerobiidae, Cunaxidae, Trombidiidae, Trombiculidae, Erythraeidae and Bdellidae have silk glands used to produce silk for various purposes. Additionally, water mites (Hydrachnidia) produce long thin threads that may be silk. The sexes are separate in mites; males have
580-418: A pair of testes in the mid-region of the body, each connected to the gonopore by a vas deferens , and in some species there is a chitinous penis ; females have a single ovary connected to the gonopore by an oviduct , as well as a seminal receptacle for the storage of sperm . In most mites, sperm is transferred to the female indirectly; the male either deposits a spermatophore on a surface from which it
638-422: A phylum may have been lost by some members. Also, this definition is based on an arbitrary point of time: the present. However, as it is character based, it is easy to apply to the fossil record. A greater problem is that it relies on a subjective decision about which groups of organisms should be considered as phyla. The approach is useful because it makes it easy to classify extinct organisms as " stem groups " to
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#1733085073607696-689: A phylum, other phylum-level ranks appear, such as the case of Bacillariophyta (diatoms) within Ochrophyta . These differences became irrelevant after the adoption of a cladistic approach by the ISP, where taxonomic ranks are excluded from the classifications after being considered superfluous and unstable. Many authors prefer this usage, which lead to the Chromista-Protozoa scheme becoming obsolete. Currently there are 40 bacterial phyla (not including " Cyanobacteria ") that have been validly published according to
754-448: A range of taxa. Oribatida and Prostigmata are more numerous in soil than Mesostigmata, and have more soil-dwelling species. When soil is affected by an ecological disturbance such as agriculture, most mites (Astigmata, Mesostigmata and Prostigmata) recolonise it within a few months, whereas Oribatida take multiple years. Many mites are parasitic on plants and animals. One family of mites, Pyroglyphidae , or nest mites, live primarily in
812-542: 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 ; 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
870-467: Is a paraphyletic taxon, which is less acceptable to present-day biologists than in the past. Proposals have been made to divide it among several new kingdoms, such as Protozoa and Chromista in the Cavalier-Smith system . Protist taxonomy has long been unstable, with different approaches and definitions resulting in many competing classification schemes. Many of the phyla listed below are used by
928-833: Is also prevalent in soil-dwelling Ascidae. Other habitats from which Ascidae have been collected include under bark of dead trees, on small mammals, and in nests of birds and mammals. Though mostly terrestrial, some ascids live on wet plants and detritus and on the water surface of marginal freshwater habitats. These walk about on the surface film and feed on the floating egg masses of nematocerous flies such as mosquitoes . Ascidae can disperse to new environments via phoresis : riding on larger arthropods. Species of Arctoseius are phoretic on adults of mushroom sciarid fly, Lycoriella auripila (whose eggs and larvae they consume), while aquatic ascids are phoretic on adult crane flies . Ascidae occur in many countries and regions. The highest numbers of species, endemic species and genera occur in
986-472: Is generally included in kingdom Fungi, though its exact relations remain uncertain, and it is considered a protozoan by the International Society of Protistologists (see Protista , below). Molecular analysis of Zygomycota has found it to be polyphyletic (its members do not share an immediate ancestor), which is considered undesirable by many biologists. Accordingly, there is a proposal to abolish
1044-440: 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. Mites are tiny 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, as part of
1102-491: 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 setae (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. Many mites have stigmata (openings used in respiration). In some mites,
1160-458: 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 , insemination is direct using the male's penis. The spermatophora in all mites are aflagellate. The eggs are laid in the substrate , or wherever the mite happens to live. They take up to six weeks to hatch, according to species, with the next stage being
1218-459: Is that all organisms in a phylum should be clearly more closely related to one another than to any other group. Even this is problematic because the requirement depends on knowledge of organisms' relationships: as more data become available, particularly from molecular studies, we are better able to determine the relationships between groups. So phyla can be merged or split if it becomes apparent that they are related to one another or not. For example,
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#17330850736071276-552: The Catalogue of Life , and correspond to the Protozoa-Chromista scheme, with updates from the latest (2022) publication by Cavalier-Smith . Other phyla are used commonly by other authors, and are adapted from the system used by the International Society of Protistologists (ISP). Some of the descriptions are based on the 2019 revision of eukaryotes by the ISP. The number of protist phyla varies greatly from one classification to
1334-617: The Palearctic . On the other hand, the most speciose genus, Asca , has the most species in the Neotropical and Oriental regions. Ascidae is believed to have originated from the Palearctic. Mite Mites are small arachnids (eight-legged arthropods ). Mites span two large orders of arachnids, the Acariformes and the Parasitiformes , which were historically grouped together in
1392-514: The Parasitiformes (sometimes known as Anactinotrichida). Recent genetic research has suggested that Acari is polyphyletic (of multiple origins). A study using molecular data from the mitochondria and nucleus recovered Acariformes as sister to the Solifugae (camel spiders) and Parasitiformes as sister to the Pseudoscorpionida , with other arachnid orders separating these two groupings on
1450-548: The Rhynie Chert , Scotland, which dates to the early Devonian , around 410 million years ago while the earliest fossils of Parasitiformes are known from amber specimens dating to the mid- Cretaceous , around 100 million years ago. Most fossil acarids are no older than the Tertiary (up to 65 mya ). Members of the superorders Opilioacariformes and Acariformes (sometimes known as Actinotrichida) are mites, as well as some of
1508-459: The bearded worms were described as a new phylum (the Pogonophora) in the middle of the 20th century, but molecular work almost half a century later found them to be a group of annelids , so the phyla were merged (the bearded worms are now an annelid family ). On the other hand, the highly parasitic phylum Mesozoa was divided into two phyla ( Orthonectida and Rhombozoa ) when it was discovered
1566-417: The carbon cycle . Two species live on humans, namely Demodex folliculorum and Demodex brevis ; both are frequently referred to as eyelash mites. The majority of mite species are harmless to humans and domestic animals , but a few species can colonize mammals directly, acting as vectors for disease transmission, and causing or contributing to allergenic diseases. Mites which colonize human skin are
1624-625: The chelicerae , the pedipalps and the oral cavity. It is covered above by an extension of the body carapace and is connected to the body by a flexible section of cuticle . Two-segmented chelicerae is the ancestral condition in Acariformes, but in more derived groups they are single-segmented. And three-segmented chelicerae is the ancestral condition in Parasitiformes, but has been reduced to just two segments in more derived groups. The pedipalps differ between taxa depending on diet; in some species
1682-511: 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". In 1898, Arthur Conan Doyle wrote a satirical poem, "A Parable", with the conceit of some cheese mites disputing the origin of the round cheddar cheese in which they all lived. The world's first science documentary featured cheese mites , seen under
1740-593: The Acari has been relatively little studied, but molecular information from ribosomal DNA 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 , and the 18S ribosomal RNA and 28S ribosomal RNA genes, provide clues at deeper levels. The mite fossil record is sparse, due to their small size and low preservation potential. The oldest fossils of acariform mites are from
1798-495: The Greek phylon ( φῦλον , "race, stock"), related to phyle ( φυλή , "tribe, clan"). Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity"): "perhaps such a real and completely self-contained unity is the aggregate of all species which have gradually evolved from one and
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1856-510: The Orthonectida are probably deuterostomes and the Rhombozoa protostomes . This changeability of phyla has led some biologists to call for the concept of a phylum to be abandoned in favour of placing taxa in clades without any formal ranking of group size. A definition of a phylum based on body plan has been proposed by paleontologists Graham Budd and Sören Jensen (as Haeckel had done
1914-491: The Zygomycota phylum. Its members would be divided between phylum Glomeromycota and four new subphyla incertae sedis (of uncertain placement): Entomophthoromycotina , Kickxellomycotina , Mucoromycotina , and Zoopagomycotina . Kingdom Protista (or Protoctista) is included in the traditional five- or six-kingdom model, where it can be defined as containing all eukaryotes that are not plants, animals, or fungi. Protista
1972-546: 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 (two pairs in Eriophyoidea ), each with six segments, which may be modified for swimming or other purposes. The dorsal surface of the body is clad in hardened tergites and the ventral surface by hardened sclerites ; sometimes these form transverse ridges. The gonopore (genital opening)
2030-642: The body of honey bees , and Acarapis woodi (family Tarsonemidae ) lives in their tracheae . Hundreds of species are associated with other bees, mostly poorly described. They attach to bees in a variety of ways. For example, 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 . Mites also parasitize some ant species, such as Eciton burchellii . Most larvae of Parasitengona are ectoparasites of arthropods, while later life stages in this group tend to shift to being predators. Plant pests include
2088-407: The cause of several types of itchy skin rashes, such as gamasoidosis , rodent mite dermatitis , grain itch , grocer's itch , and 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
2146-437: The commercially destructive Varroa parasite of honey bees , as well as 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 . The mites are not a defined taxon, but is used for two distinct groups of arachnids, the Acariformes and the Parasitiformes . The phylogeny of
2204-428: 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 . 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 ,
2262-504: The first publication of the APG system in 1998, which proposed a classification of angiosperms up to the level of orders , many sources have preferred to treat ranks higher than orders as informal clades. Where formal ranks have been provided, the traditional divisions listed below have been reduced to a very much lower level, e.g. subclasses . Wolf plants Hepatophyta Liver plants Coniferophyta Cone-bearing plant Phylum Microsporidia
2320-468: The four embranchements of Georges Cuvier . Informally, phyla can be thought of as groupings of organisms based on general specialization of body plan . At its most basic, a phylum can be defined in two ways: as a group of organisms with a certain degree of morphological or developmental similarity (the phenetic definition), or a group of organisms with a certain degree of evolutionary relatedness (the phylogenetic definition). Attempting to define
2378-417: 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 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
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2436-536: The idea that each of the phyla represents a distinct body plan. A classification using this definition may be strongly affected by the chance survival of rare groups, which can make a phylum much more diverse than it would be otherwise. Total numbers are estimates; figures from different authors vary wildly, not least because some are based on described species, some on extrapolations to numbers of undescribed species. For instance, around 25,000–27,000 species of nematodes have been described, while published estimates of
2494-703: The influential (though contentious) Cavalier-Smith system in equating "Plantae" with Archaeplastida , a group containing Viridiplantae and the algal Rhodophyta and Glaucophyta divisions. The definition and classification of plants at the division level also varies from source to source, and has changed progressively in recent years. Thus some sources place horsetails in division Arthrophyta and ferns in division Monilophyta, while others place them both in Monilophyta, as shown below. The division Pinophyta may be used for all gymnosperms (i.e. including cycads, ginkgos and gnetophytes), or for conifers alone as below. Since
2552-584: The microscope; the short film was shown in London's Alhambra music hall in 1903, causing a boom in the sales of simple microscopes. Phylum In biology , a phylum ( / ˈ f aɪ l əm / ; pl. : phyla ) is a level of classification or taxonomic rank below kingdom and above class . Traditionally, in botany the term division has been used instead of phylum, although the International Code of Nomenclature for algae, fungi, and plants accepts
2610-612: The most diverse and successful of all invertebrate groups. They have exploited a wide array of habitats , and because of their small size go largely unnoticed. They are found in freshwater (e.g. the water mites or Hydrachnidia ) and saltwater (most Halacaridae ), 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 of plants and animals. Some 48,200 species of mites have been described, but there may be
2668-506: The nests of birds and other animals. These mites are largely parasitic and consume blood , skin and keratin . Dust mites , 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 are a prominent group of mites that are parasitic on vertebrates, mostly mammal and birds, feeding on blood with specialised mouthparts. Parasitic mites sometimes infest insects. Varroa destructor attaches to
2726-411: The next. The Catalogue of Life includes Rhodophyta and Glaucophyta in kingdom Plantae, but other systems consider these phyla part of Protista. In addition, less popular classification schemes unite Ochrophyta and Pseudofungi under one phylum, Gyrista , and all alveolates except ciliates in one phylum Myzozoa , later lowered in rank and included in a paraphyletic phylum Miozoa . Even within
2784-436: The phyla with which they bear the most resemblance, based only on the taxonomically important similarities. However, proving that a fossil belongs to the crown group of a phylum is difficult, as it must display a character unique to a sub-set of the crown group. Furthermore, organisms in the stem group of a phylum can possess the "body plan" of the phylum without all the characteristics necessary to fall within it. This weakens
2842-413: The phylogenetic tree, as shown below. Palpigradi False scorpions [REDACTED] Ixodida (ticks) [REDACTED] Parasitic mites, inc. Varroa [REDACTED] Trombidiformes (chiggers, velvet mites, etc) [REDACTED] Sarcoptiformes (dust & fur mites, etc) [REDACTED] Camel spiders [REDACTED] other Arachnids including spiders and scorpions However,
2900-411: The same common original form, as, for example, all vertebrates. We name this aggregate [a] Stamm [i.e., stock] ( Phylon )." In plant taxonomy , August W. Eichler (1883) classified plants into five groups named divisions, a term that remains in use today for groups of plants, algae and fungi. The definitions of zoological phyla have changed from their origins in the six Linnaean classes and
2958-515: The shield's posterior margin, genital shield truncate to convex posteriorly (tapering in some Antennoseius ), with an anal shield bearing only circumanal setae (rare) or a ventrianal shield bearing additionally up to seven pairs of setae, and spermathecal apparatus laelapid -type. This family is morphologically similar to Blattisociidae and Melicharidae , and these families were formerly included within Ascidae. The life cycle of Ascidae consists of
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#17330850736073016-564: The six-legged larvae. 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 compared to many other arachnids. Mites occupy a wide range of ecological niches . For example, Oribatida mites are important decomposers in many habitats. They eat a wide variety of material including living and dead plant and fungal material, lichens and carrion; some are predatory , though no oribatid mites are parasitic . Mites are among
3074-477: The so-called spider mites (family Tetranychidae ), thread-footed mites (family Tarsonemidae ), and the gall mites (family Eriophyidae ). Among the species that attack animals are members of the sarcoptic mange mites (family Sarcoptidae ), which burrow under the skin. Demodex mites (family Demodecidae ) are parasites that live in or near the hair follicles of mammals , including humans. Being unable to fly, mites need some other means of dispersal. On
3132-548: The stages egg, larva, protonymph, deutonymph and adult. Each stage has a duration measurable in days. The total lifespan is similarly short, being on average 27 days in Arctoseius semiscissus and 19 days in Proctolaelaps deleoni . Ascidae include epedaphic species that hunt on the soil surface in the litter layer. These prey on other small arthropods, particularly springtails (Collembola). Nematophagy (consumption of nematodes )
3190-505: The stigmata are associated with peritremes: paired, tubular, elaborated extensions of the tracheal system. The higher taxa of mites are defined by these structures: 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
3248-579: The subclass Acari . However, most recent genetic analyses do not recover the two as each other's closest relative within Arachnida, rendering the group non- monophyletic . Most mites are tiny, less than 1 mm (0.04 in) 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 decomposers , others live on plants, sometimes creating galls , while others are predators or parasites . This last type includes
3306-416: The terms as equivalent. Depending on definitions, the animal kingdom Animalia contains about 31 phyla, the plant kingdom Plantae contains about 14 phyla, and the fungus kingdom Fungi contains about 8 phyla. Current research in phylogenetics is uncovering the relationships among phyla within larger clades like Ecdysozoa and Embryophyta . The term phylum was coined in 1866 by Ernst Haeckel from
3364-420: The total number of nematode species include 10,000–20,000; 500,000; 10 million; and 100 million. The kingdom Plantae is defined in various ways by different biologists (see Current definitions of Plantae ). All definitions include the living embryophytes (land plants), to which may be added the two green algae divisions, Chlorophyta and Charophyta , to form the clade Viridiplantae . The table below follows
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