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Acarian
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 the subclass Acari, but genetic analysis does not show clear evidence of a close relationship. 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 decomposers, others live on plants, sometimes creating galls, while others again are predators or parasites. This last type includes 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. Evolution and taxonomy The mites are not a defined taxon, but is used for two distinct groups of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Early Devonian
The Early Devonian is the first of three Epoch (geology), epochs comprising the Devonian period, corresponding to the Lower Devonian Series (stratigraphy), series. It lasted from and began with the Lochkovian Stage , which was followed by the Pragian from and then by the Emsian, which lasted until the Middle Devonian began, . During this time, the first Ammonoidea, ammonoids appeared, descending from Bactritida, bactritoid Nautiloidea, nautiloids. Ammonoids during this time period were simple and differed little from their nautiloid counterparts. These ammonoids belong to the order Agoniatitida, which in later epochs evolved to new ammonoid orders, for example Goniatite, Goniatitida and Clymeniida. This class of cephalopod molluscs would dominate the marine fauna until the beginning of the Mesozoic Era. References {{Geological history Early Devonian, Geological epochs Devonian geochronology, *01 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ribosomal DNA
Ribosomal DNA (rDNA) is a DNA sequence that codes for ribosomal RNA. These sequences regulate transcription initiation and amplification, and contain both transcribed and non-transcribed spacer segments. In the human genome there are 5 chromosomes with nucleolus organizer regions: the acrocentric chromosomes 13 (RNR1), 14 ( RNR2), 15 ( RNR3), 21 (RNR4) and 22 (RNR5). The genes that are responsible for encoding the various sub-units of rRNA are located across multiple chromosomes in humans. But the genes that encode for rRNA are highly conserved across the domains, with only the copy numbers involved for the genes having varying numbers per species. In Bacteria, Archaea, and chloroplasts the rRNA is composed of different (smaller) units, the large (23S) ribosomal RNA, 16S ribosomal RNA and 5S rRNA. The 16S rRNA is widely used for phylogenetic studies. Eukaryotes The rRNA transcribed from the approximately 600 rDNA repeats forms the most abundant section of RNA found in cells ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monogynaspida
Mesostigmata is an order of mites belonging to the Parasitiformes. They are by far the largest group of Parasitiformes, with over 8,000 species in 130 families. Mesostigmata includes parasitic as well as free-living and predatory forms. They can be recognized by the single pair of spiracles positioned laterally on the body. The family with the most described species is Phytoseiidae. Other families of note are Diplogyniidae, Macrochelidae, Pachylaelapidae, Uropodidae and Veigaiidae. Amongst the best known species are ''Varroa destructor'', an economically important parasite of honey bees, as well as the red mite (''Dermanyssus gallinae'') a parasite of poultry, most commonly chickens. Description Mesostigmata are mites ranging from 0.12-4 mm long (0.2-4 mm according to another source). They have a pair of stigmatal openings above legs III-IV usually associated with a peritrematal groove. The gnathosoma has a sclerotised ring around the bases of the chelicerae (basis capitul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trigynaspida
Trigynaspida is a suborder of mites in the order Mesostigmata. There are more than 25 families and at least 90 described species in Trigynaspida. Families These 27 families belong to the suborder Trigynaspida: * Aenictequidae Kethley, 1977 * Antennophoridae Berlese, 1892 * Asternoseiidae Vale, 1954 * Celaenopsidae Berlese, 1892 * Cercomegistidae Trägårdh, 1937 * Costacaridae Hunter, 1993 * Davacaridae Kethley, 1977 * Diplogyniidae Trägårdh, 1941 * Euphysalozerconidae Kim, 2008 * Euzerconidae Trägårdh, 1938 * Fedrizziidae Trägårdh, 1937 * Hoplomegistidae Camin & Gorirossi, 1955 * Klinckowstroemiidae Camin & Gorirossi, 1955 * Megacelaenopsidae Funk, 1975 * Megisthanidae Berlese, 1914 * Messoracaridae Kethley, 1977 * Neotenogyniidae Kethley, 1974 * Paramegistidae Trägårdh, 1946 * Parantennulidae Willmann, 1941 * Philodanidae Kethley, 1977 * Promegistidae Kethley, 1977 * Ptochacaridae Kethley, 1977 * Pyrosejidae Lindquist & Moraza, 1993 * Saltiseiidae Walter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mesostigmata
Mesostigmata is an order of mites belonging to the Parasitiformes. They are by far the largest group of Parasitiformes, with over 8,000 species in 130 families. Mesostigmata includes parasitic as well as free-living and predatory forms. They can be recognized by the single pair of spiracles positioned laterally on the body. The family with the most described species is Phytoseiidae. Other families of note are Diplogyniidae, Macrochelidae, Pachylaelapidae, Uropodidae and Veigaiidae. Amongst the best known species are ''Varroa destructor'', an economically important parasite of honey bees, as well as the red mite (''Dermanyssus gallinae'') a parasite of poultry, most commonly chickens. Description Mesostigmata are mites ranging from 0.12-4 mm long (0.2-4 mm according to another source). They have a pair of stigmatal openings above legs III-IV usually associated with a peritrematal groove. The gnathosoma has a sclerotised ring around the bases of the chelicerae (basis capitul ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ixodida
Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by feeding on the blood of mammals, birds, and sometimes reptiles and amphibians. The timing of the origin of ticks is uncertain, though the oldest known tick fossils are from the Cretaceous period, around 100 million years old. Ticks are widely distributed around the world, especially in warm, humid climates. Ticks belong to two major families, the Ixodidae or hard ticks, and the Argasidae, or soft ticks. ''Nuttalliella,'' a genus of tick from southern Africa is the only member of the family Nuttalliellidae, and represents the most primitive living lineage of ticks. Adults have ovoid/pear-shaped bodies (idiosomas) which become engorged with blood when they feed, and eight legs. Their cephalothorax and abdomen are completely fused. In additi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gondwana
Gondwana () was a large landmass, often referred to as a supercontinent, that formed during the late Neoproterozoic (about 550 million years ago) and began to break up during the Jurassic period (about 180 million years ago). The final stages of break-up, involving the separation of Antarctica from South America (forming the Drake Passage) and Australia, occurred during the Paleogene. Gondwana was not considered a supercontinent by the earliest definition, since the landmasses of Baltica, Laurentia, and Siberia were separated from it. To differentiate it from the Indian region of the same name (see ), it is also commonly called Gondwanaland. Gondwana was formed by the accretion of several cratons. Eventually, Gondwana became the largest piece of continental crust of the Palaeozoic Era, covering an area of about , about one-fifth of the Earth's surface. During the Carboniferous Period, it merged with Laurasia to form a larger supercontinent called Pangaea. Gondwana (and Pan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Holothyrida
The Holothyrida are a small order of mites in the superorder Parasitiformes. No fossils are known. With body lengths of more than they are relatively large mites, with a heavily sclerotized body. It is divided into three families, Allothyridae, Holothyridae, and Neothyridae. In a 1998 experimental study, members of the family Allothyridae were found to ignore living animals but readily fed on the body fluids of death arthropods. The order has a distribution largely confined to former Gondwanan landmasses. They are the sister group to Ixodida (ticks).Dobson & Barker 1999 Systematics Allothyridae Allothyridae van der Hammen, 1972 — Australia, New Zealand * '' Allothyrus'' van der Hammen, 1961 :* '' Allothyrus australasiae'' (Womersley, 1935) :* '' Allothyrus constrictus'' (Domrow, 1955) * '' Australothyrus'' van der Hammen, 1983 :* '' Australothyrus ocellatus'' van der Hammen, 1983 Holothyridae Holothyridae Thorell, 1882 Sri Lanka, Indian Ocean islands, New Guinea, New ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opiliones
The Opiliones (formerly Phalangida) are an order of arachnids colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs. , over 6,650 species of harvestmen have been discovered worldwide, although the total number of extant species may exceed 10,000. The order Opiliones includes five suborders: Cyphophthalmi, Eupnoi, Dyspnoi, Laniatores, and Tetrophthalmi, which were named in 2014. Representatives of each extant suborder can be found on all continents except Antarctica. Well-preserved fossils have been found in the 400-million-year-old Rhynie cherts of Scotland, and 305-million-year-old rocks in France. These fossils look surprisingly modern, indicating that their basic body shape developed very early on, and, at least in some taxa, has changed little since that time. Their phylogenetic position within the Arachnida is disputed; their closest relatives may be the mites (Acari) or the Novogenuata (the Scorpiones, Pseudoscorpiones, and Solifugae). Althou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harvestmen
The Opiliones (formerly Phalangida) are an order of arachnids colloquially known as harvestmen, harvesters, harvest spiders, or daddy longlegs. , over 6,650 species of harvestmen have been discovered worldwide, although the total number of extant species may exceed 10,000. The order Opiliones includes five suborders: Cyphophthalmi, Eupnoi, Dyspnoi, Laniatores, and Tetrophthalmi, which were named in 2014. Representatives of each extant suborder can be found on all continents except Antarctica. Well-preserved fossils have been found in the 400-million-year-old Rhynie cherts of Scotland, and 305-million-year-old rocks in France. These fossils look surprisingly modern, indicating that their basic body shape developed very early on, and, at least in some taxa, has changed little since that time. Their phylogenetic position within the Arachnida is disputed; their closest relatives may be the mites (Acari) or the Novogenuata (the Scorpiones, Pseudoscorpiones, and Solifugae). Altho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Opilioacarida
Opilioacaridae is the sole family of mites in the order Opilioacarida, made up of about 13 genera. The mites of this family are rare, large (1.5 to 2.5 mm) mites, and are widely considered primitive, as they retain six pairs of eyes, and abdominal segmentation. They have historically been considered separate from other mites belonging to Acariformes and Parasitiformes, but are now generally considered a subgroup of Parasitiformes based on molecular phylogenetics. The first member of the Opilioacarida to be discovered was the Algerian species '' Opilioacarus segmentatus'', which was described by Carl Johannes With in 1902, followed by the Sicilian '' Eucarus italicus'' and '' Eucarus arabicus'' from Aden, both in 1904. Two fossil specimens are known, one of which was discovered in Baltic amber from the Eocene, while the other one was discovered in the Burmese amber from the Late Cretaceous (Cenomanian The Cenomanian is, in the ICS' geological timescale, the oldest or ea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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 alias of 25S–28S rRNA. Combined with 5.8S rRNA to the 5' side, it is the eukaryotic nuclear homologue of the prokaryotic 23S and mitochondrial 16S ribosomal RNAs. Use in phylogeny The genes coding for 28S rRNA are referred to as 28S rDNA. The comparison of the sequences from these genes are sometimes used in molecular analysis to construct phylogenetic trees, for example in protists, fungi, insects, arachnids, tardigrades, and vertebrates. Structure The 28S rRNA is typically 4000–5000 nt long. Some eukaryotes cleave 28S rRNA into two parts before assembling both into the ribosome, a phenomenon termed the "hidden break". Databases Several databases provide alignments and annotations of LSU rRNA sequences for comparati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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