1.
Taxonomy (biology)
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Taxonomy is the science of defining groups of biological organisms on the basis of shared characteristics and giving names to those groups. The exact definition of taxonomy varies from source to source, but the core of the remains, the conception, naming. There is some disagreement as to whether biological nomenclature is considered a part of taxonomy, the broadest meaning of taxonomy is used here. The word taxonomy was introduced in 1813 by Candolle, in his Théorie élémentaire de la botanique, the term alpha taxonomy is primarily used today to refer to the discipline of finding, describing, and naming taxa, particularly species. In earlier literature, the term had a different meaning, referring to morphological taxonomy, ideals can, it may be said, never be completely realized. They have, however, a value of acting as permanent stimulants. Some of us please ourselves by thinking we are now groping in a beta taxonomy, turrill thus explicitly excludes from alpha taxonomy various areas of study that he includes within taxonomy as a whole, such as ecology, physiology, genetics, and cytology. He further excludes phylogenetic reconstruction from alpha taxonomy, thus, Ernst Mayr in 1968 defined beta taxonomy as the classification of ranks higher than species. This activity is what the term denotes, it is also referred to as beta taxonomy. How species should be defined in a group of organisms gives rise to practical and theoretical problems that are referred to as the species problem. The scientific work of deciding how to define species has been called microtaxonomy, by extension, macrotaxonomy is the study of groups at higher taxonomic ranks, from subgenus and above only, than species. While some descriptions of taxonomic history attempt to date taxonomy to ancient civilizations, earlier works were primarily descriptive, and focused on plants that were useful in agriculture or medicine. There are a number of stages in scientific thinking. Early taxonomy was based on criteria, the so-called artificial systems. Later came systems based on a complete consideration of the characteristics of taxa, referred to as natural systems, such as those of de Jussieu, de Candolle and Bentham. The publication of Charles Darwins Origin of Species led to new ways of thinking about classification based on evolutionary relationships and this was the concept of phyletic systems, from 1883 onwards. This approach was typified by those of Eichler and Engler, the advent of molecular genetics and statistical methodology allowed the creation of the modern era of phylogenetic systems based on cladistics, rather than morphology alone. Taxonomy has been called the worlds oldest profession, and naming and classifying our surroundings has likely been taking place as long as mankind has been able to communicate
2.
Animal
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Animals are multicellular, eukaryotic organisms of the kingdom Animalia. The animal kingdom emerged as a clade within Apoikozoa as the group to the choanoflagellates. Animals are motile, meaning they can move spontaneously and independently at some point in their lives and their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later in their lives. All animals are heterotrophs, they must ingest other organisms or their products for sustenance, most known animal phyla appeared in the fossil record as marine species during the Cambrian explosion, about 542 million years ago. Animals can be divided broadly into vertebrates and invertebrates, vertebrates have a backbone or spine, and amount to less than five percent of all described animal species. They include fish, amphibians, reptiles, birds and mammals, the remaining animals are the invertebrates, which lack a backbone. These include molluscs, arthropods, annelids, nematodes, flatworms, cnidarians, ctenophores, the study of animals is called zoology. The word animal comes from the Latin animalis, meaning having breath, the biological definition of the word refers to all members of the kingdom Animalia, encompassing creatures as diverse as sponges, jellyfish, insects, and humans. Aristotle divided the world between animals and plants, and this was followed by Carl Linnaeus, in the first hierarchical classification. In Linnaeuss original scheme, the animals were one of three kingdoms, divided into the classes of Vermes, Insecta, Pisces, Amphibia, Aves, and Mammalia. Since then the last four have all been subsumed into a single phylum, in 1874, Ernst Haeckel divided the animal kingdom into two subkingdoms, Metazoa and Protozoa. The protozoa were later moved to the kingdom Protista, leaving only the metazoa, thus Metazoa is now considered a synonym of Animalia. Animals have several characteristics that set apart from other living things. Animals are eukaryotic and multicellular, which separates them from bacteria and they are heterotrophic, generally digesting food in an internal chamber, which separates them from plants and algae. They are also distinguished from plants, algae, and fungi by lacking cell walls. All animals are motile, if only at life stages. In most animals, embryos pass through a stage, which is a characteristic exclusive to animals. With a few exceptions, most notably the sponges and Placozoa and these include muscles, which are able to contract and control locomotion, and nerve tissues, which send and process signals
3.
Arthropod
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An arthropod is an invertebrate animal having an exoskeleton, a segmented body, and jointed appendages. Arthropods form the phylum Arthropoda, which includes the insects, arachnids, myriapods, arthropods are characterized by their jointed limbs and cuticle made of chitin, often mineralised with calcium carbonate. The arthropod body plan consists of segments, each with a pair of appendages, the rigid cuticle inhibits growth, so arthropods replace it periodically by moulting. Their versatility has enabled them to become the most species-rich members of all guilds in most environments. They have over a million described species, making up more than 80% of all described living species, some of which. Arthropods range in size from the microscopic crustacean Stygotantulus up to the Japanese spider crab, arthropods primary internal cavity is a hemocoel, which accommodates their internal organs, and through which their haemolymph – analogue of blood – circulates, they have open circulatory systems. Like their exteriors, the organs of arthropods are generally built of repeated segments. Their nervous system is ladder-like, with paired ventral nerve cords running through all segments and their heads are formed by fusion of varying numbers of segments, and their brains are formed by fusion of the ganglia of these segments and encircle the esophagus. The respiratory and excretory systems of arthropods vary, depending as much on their environment as on the subphylum to which they belong, arthropods also have a wide range of chemical and mechanical sensors, mostly based on modifications of the many setae that project through their cuticles. Aquatic species use internal or external fertilization. Almost all arthropods lay eggs, but scorpions give birth to live young after the eggs have hatched inside the mother, arthropod hatchlings vary from miniature adults to grubs and caterpillars that lack jointed limbs and eventually undergo a total metamorphosis to produce the adult form. The level of care for hatchlings varies from nonexistent to the prolonged care provided by scorpions. The evolutionary ancestry of arthropods dates back to the Cambrian period, the group is generally regarded as monophyletic, and many analyses support the placement of arthropods with cycloneuralians in a superphylum Ecdysozoa. Overall however, the relationships of Metazoa are not yet well resolved. Likewise, the relationships between various groups are still actively debated. Arthropods contribute to the food supply both directly as food, and more importantly indirectly as pollinators of crops. Some species are known to spread disease to humans, livestock. The word arthropod comes from the Greek ἄρθρον árthron, joint, and πούς pous, i. e. foot or leg, arthropods are invertebrates with segmented bodies and jointed limbs
4.
Arachnid
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Arachnids are a class of joint-legged invertebrate animals, in the subphylum Chelicerata. The term is derived from the Greek word ἀράχνη, meaning spider, spiders are the largest order in the class. Almost all extant arachnids are terrestrial, living mainly on land, however, some inhabit freshwater environments and, with the exception of the pelagic zone, marine environments as well. They comprise over 100,000 named species, including spiders, scorpions, harvestmen, ticks, mites, almost all adult arachnids have eight legs, and arachnids may be easily distinguished from insects by this fact, since insects have six legs. However, arachnids also have two pairs of appendages that have become adapted for feeding, defense, and sensory perception. The first pair, the chelicerae, serve in feeding and defense, the next pair of appendages, the pedipalps, have been adapted for feeding, locomotion, and/or reproductive functions. In Solifugae, the palps are quite leg-like, so that animals appear to have ten legs. The larvae of mites and Ricinulei have only six legs, a fourth pair usually appears when they moult into nymphs, however, mites are variable, as well as eight, there are adult mites with six or even four legs. Arachnids are further distinguished from insects by the fact they do not have antennae or wings and their body is organized into two tagmata, called the prosoma, or cephalothorax, and the opisthosoma, or abdomen. The cephalothorax is derived from the fusion of the cephalon and the thorax, the abdomen is segmented in the more primitive forms, but varying degrees of fusion between the segments occur in many groups. It is typically divided into a preabdomen and postabdomen, although this is clearly visible in scorpions, and in some orders, such as the Acari. A telson is present in scorpions, where it has modified to a stinger. Like all arthropods, arachnids have an exoskeleton, and they also have a structure of cartilage-like tissue, called the endosternite. The endosternite is even calcified in some Opiliones, most arachnids lack extensor muscles in the distal joints of their appendages. Spiders and whipscorpions extend their limbs hydraulically using the pressure of their hemolymph, solifuges and some harvestmen extend their knees by the use of highly elastic thickenings in the joint cuticle. Scorpions, pseudoscorpions and some harvestmen have evolved muscles that extend two leg joints at once, the equivalent joints of the pedipalps of scorpions though, are extended by elastic recoil. This type of system has almost certainly evolved from the book lungs. The excretory glands of arachnids include up to four pairs of coxal glands along the side of the prosoma, many arachnids have only one or the other type of excretory gland, although several do have both
5.
Biodiversity
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Biodiversity, a contraction of biological diversity, generally refers to the variety and variability of life on Earth. One of the most widely used definitions defines it in terms of the variability within species and it is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation within an area, biome, terrestrial biodiversity tends to be greater near the equator, which seems to be the result of the warm climate and high primary productivity. Biodiversity is not distributed evenly on Earth, and is richest in the tropics and these tropical forest ecosystems cover less than 10 per cent of earths surface, and contain about 90 percent of the worlds species. Marine biodiversity tends to be highest along coasts in the Western Pacific, there are latitudinal gradients in species diversity. Biodiversity generally tends to cluster in hotspots, and has been increasing through time, the number and variety of plants, animals and other organisms that exist is known as biodiversity. It is a component of nature and it ensures the survival of human species by providing food, fuel, shelter, medicines. The richness of biodiversity depends on the conditions and area of the region. All species of plants taken together are known as flora and about 300,000 species of plants are known to date, all species of animals taken together are known as fauna which includes birds, mammals, fish, reptiles, insects, crustaceans, molluscs, etc. Rapid environmental changes typically cause mass extinctions, more than 99 percent of all species, amounting to over five billion species, that ever lived on Earth are estimated to be extinct. Estimates on the number of Earths current species range from 10 million to 14 million, of which about 1.2 million have been documented and over 86 percent have not yet been described. More recently, in May 2016, scientists reported that 1 trillion species are estimated to be on Earth currently with only one-thousandth of one percent described, the total amount of related DNA base pairs on Earth is estimated at 5.0 x 1037 and weighs 50 billion tonnes. In comparison, the mass of the biosphere has been estimated to be as much as 4 TtC. In July 2016, scientists reported identifying a set of 355 genes from the Last Universal Common Ancestor of all living on Earth. The age of the Earth is about 4.54 billion years old, there are microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia. Other early physical evidence of a substance is graphite in 3.7 billion-year-old meta-sedimentary rocks discovered in Western Greenland. More recently, in 2015, remains of life were found in 4.1 billion-year-old rocks in Western Australia. According to one of the researchers, If life arose relatively quickly on Earth, then it could be common in the universe
6.
Scorpion
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Scorpions are predatory arachnids of the order Scorpiones. Scorpions range in size from 9 mm /0.3 in. to 23 cm /9 in, the evolutionary history of scorpions goes back to the Silurian era 430 million years ago. They have adapted to a range of environmental conditions and can now be found on all continents except Antarctica. Scorpions number about 1750 described species, with 13 extant families recognised to date, only about 25 of these species are known to have venom capable of killing a human being. The taxonomy has undergone changes and is likely to change further, Scorpion stings are painful but are usually harmless to humans. For stings from species found in North America, no treatment is normally needed for healthy adults, although care should be sought for children. More harmful stings from species found in South America, Africa, Scorpions are found on all major land masses except Antarctica. The greatest diversity of scorpions in the Northern Hemisphere is to be found in the areas lying between latitudes 23° N and 38° N. Above these latitudes, the diversity decreases, with the northernmost natural occurrence of scorpions being the northern scorpion Paruroctonus boreus at Medicine Hat, Alberta, five colonies of scorpions have established themselves in Sheerness on the Isle of Sheppey in the United Kingdom. This small population has been resident since the 1860s, having arrived with imported fruit from Africa. This scorpion species is small and completely harmless to humans, at just over 51° N, this marks the northernmost limit where scorpions live in the wild. There are thirteen families and about 1,750 described species and subspecies of scorpions, in addition, there are 111 described taxa of extinct scorpions. This classification is based on that of Soleglad & Fet, which replaced the older, additional taxonomic changes are from papers by Soleglad et al. The following classification covers extant taxa to the rank of family, L. Koch,1837 Family Buthidae C. L. The oldest known scorpions lived around 430 million years ago in the Silurian period and these first scorpions were believed to have had gills instead of the present forms book lungs though this has subsequently been refuted. The oldest Gondwanan scorpiones comprise the earliest known terrestrial animals from Gondwana, currently,111 fossil species of scorpion are known. Unusually for arachnids, there are species of Palaeozoic scorpion than Mesozoic or Cenozoic ones. The eurypterids, marine creatures that lived during the Palaeozoic era, share several traits with scorpions
7.
Vinegar
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Vinegar is a liquid consisting of about 5–20% acetic acid, water, and other trace chemicals, which may include flavorings. The acetic acid is produced by the fermentation of ethanol by acetic acid bacteria, Vinegar is now mainly used as a cooking ingredient, or in pickling. As the most easily manufactured mild acid, it has historically had a variety of industrial, medical. Commercial vinegar is produced either by a fast or a slow fermentation processes, in general, slow methods are used in traditional vinegars where fermentation proceeds slowly over the course of a few months or up to a year. The longer fermentation period allows for the accumulation of a non-toxic slime composed of acetic acid bacteria, fast methods add mother of vinegar to the source liquid before adding air to oxygenate and promote the fastest fermentation. In fast production processes, vinegar may be produced between 20 hours to three days, the conversion of ethanol and oxygen to acetic acid takes place by the following reaction, CH3CH2OH + O2 → CH3COOH + H2O Vinegar has been made and used by people for thousands of years. Traces of it have been found in Egyptian urns from around 3000 BC, apple cider vinegar is made from cider or apple must, and has a brownish-gold color. It is sometimes sold unfiltered and unpasteurized with the mother of vinegar present and it can be diluted with fruit juice or water or sweetened for consumption. Balsamic vinegar is an aged vinegar produced in the Modena. The original product—Traditional Balsamic Vinegar—is made from the juice, or must. It is very dark brown, rich, sweet, and complex, with the finest grades being aged in casks made variously of oak, mulberry, chestnut, cherry, juniper. Regardless of how it is produced, balsamic vinegar must be made from a grape product, a high acidity level is somewhat hidden by the sweetness of the other ingredients, making it very mellow. It ranges from yellow to golden brown in color, and has a mellow flavor, similar in some respects to rice vinegar. Because it contains no sugar, it is no sweeter than any other vinegar. In the Philippines, it often is labeled as sukang maasim, cane vinegars from Ilocos are made in two different ways. One way is to simply place sugar cane juice in large jars, the other way is through fermentation to produce a local wine known as basi. Low-quality basi is then allowed to undergo acetic acid fermentation that converts alcohol into acetic acid, a white variation has become quite popular in Brazil in recent years, where it is the cheapest type of vinegar sold. It is now common for other types of vinegar to be mixed with cane vinegar to lower the cost
8.
Carl Linnaeus
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Carl Linnaeus, also known after his ennoblement as Carl von Linné, was a Swedish botanist, physician, and zoologist, who formalised the modern system of naming organisms called binomial nomenclature. He is known by the father of modern taxonomy. Many of his writings were in Latin, and his name is rendered in Latin as Carolus Linnæus, Linnaeus was born in the countryside of Småland, in southern Sweden. He received most of his education at Uppsala University. He lived abroad between 1735 and 1738, where he studied and also published a first edition of his Systema Naturae in the Netherlands and he then returned to Sweden, where he became professor of medicine and botany at Uppsala. In the 1740s, he was sent on journeys through Sweden to find and classify plants. In the 1750s and 1760s, he continued to collect and classify animals, plants, and minerals, at the time of his death, he was one of the most acclaimed scientists in Europe. The philosopher Jean-Jacques Rousseau sent him the message, Tell him I know no man on earth. The German writer Johann Wolfgang von Goethe wrote, With the exception of Shakespeare and Spinoza, Swedish author August Strindberg wrote, Linnaeus was in reality a poet who happened to become a naturalist. Among other compliments, Linnaeus has been called Princeps botanicorum, The Pliny of the North and he is also considered as one of the founders of modern ecology. In botany, the abbreviation used to indicate Linnaeus as the authority for species names is L. In older publications, sometimes the abbreviation Linn. is found, Linnæus was born in the village of Råshult in Småland, Sweden, on 23 May 1707. He was the first child of Nicolaus Ingemarsson and Christina Brodersonia and his siblings were Anna Maria Linnæa, Sofia Juliana Linnæa, Samuel Linnæus, and Emerentia Linnæa. One of a line of peasants and priests, Nils was an amateur botanist, a Lutheran minister. Christina was the daughter of the rector of Stenbrohult, Samuel Brodersonius, a year after Linnæus birth, his grandfather Samuel Brodersonius died, and his father Nils became the rector of Stenbrohult. The family moved into the rectory from the curates house, even in his early years, Linnæus seemed to have a liking for plants, flowers in particular. Whenever he was upset, he was given a flower, which calmed him. Nils spent much time in his garden and often showed flowers to Linnaeus, soon Linnæus was given his own patch of earth where he could grow plants
9.
Opiliones
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The Opiliones are an order of arachnids colloquially known as harvestmen, harvesters or daddy longlegs. Although both harvestmen and spiders are arachnids, the two orders are not otherwise closely related, as of December 2011, over 6,500 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, with the exception of the Dyspnoi, representatives of each can be found on every continent except Antarctica. Their phylogenetic position within the Arachnida is disputed, their closest relatives may be the mites or the Novogenuata, although superficially similar to and often misidentified as spiders, the Opiliones are a distinct order that is not closely related to spiders. They can be distinguished from long-legged spiders by their fused body regions. Spiders have an abdomen that is separated from the cephalothorax by a constriction. The Opiliones are known for having long legs relative to their body size, however. As in the Araneae, the body in the Opiliones has two tagmata, the anterior cephalothorax or prosoma, and the posterior 10-segmented abdomen or opisthosoma, other differences are that the Opiliones have no venom glands in their chelicerae and therefore pose no danger to humans. They also have no silk glands and therefore do not build webs, in some highly derived species, the first five abdominal segments are fused into a dorsal shield called the scutum, which in most such species is fused with the carapace. Some such Opiliones only have this shield in the males, in some species, the two posterior abdominal segments are reduced. Some of them are divided medially on the surface to form two plates beside each other, the second pair of legs is longer than the others and function as antennae or feelers. In short-legged species, this may not be obvious, the feeding apparatus differs from most arachnids in that Opiliones can swallow chunks of solid food, not only liquids. The stomotheca is formed by extensions from the pedipalps and the first pair of legs, the Opiliones have a single pair of eyes in the middle of the head, oriented sideways. A 305-million-year-old fossilized Opiliones with two pairs of eyes was reported in 2014, however, some species are eyeless, such as the Brazilian Caecobunus termitarum from termite nests, Giupponia chagasi from caves, and all species of the Guasiniidae. Harvestmen have a pair of prosomatic scent glands that secrete a peculiar-smelling fluid when disturbed. In some species, the fluid contains noxious quinones and they do not have book lungs, and breathe through tracheae. A pair of spiracles is located between the base of the pair of legs and the abdomen, with one opening on each side. In more active species, spiracles are also found upon the tibia of the legs and they have a gonopore on the ventral cephalothorax, and the copulation is direct as male Opiliones have a penis, unlike other arachnids
10.
Flagellum
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A flagellum is a lash-like appendage that protrudes from the cell body of certain prokaryotic and eukaryotic cells. The word flagellum in Latin means whip, the primary role of the flagellum is locomotion, but it also often has function as a sensory organelle, being sensitive to chemicals and temperatures outside the cell. Flagella are organelles defined by function rather than structure, large differences occur between different types of flagella, the prokaryotic and eukaryotic flagella differ greatly in protein composition, structure, and mechanism of propulsion. However, both can be used for swimming, an example of a flagellated bacterium is the ulcer-causing Helicobacter pylori, which uses multiple flagella to propel itself through the mucus lining to reach the stomach epithelium. An example of a eukaryotic cell is the mammalian sperm cell. Eukaryotic flagella are structurally identical to eukaryotic cilia, although distinctions are made according to function and/or length. Fimbriae and pili are also thin appendages, but have different functions and are usually smaller, three types of flagella have so far been distinguished, bacterial, archaeal, and eukaryotic. The main differences among these three types are, Bacterial flagella are helical filaments, each with a motor at its base which can turn clockwise or counterclockwise. They provide two of several kinds of bacterial motility, archaeal flagella are superficially similar to bacterial flagella, but are different in many details and considered non-homologous. Eukaryotic flagella—those of animal, plant, and protist cells—are complex cellular projections that lash back, eukaryotic flagella are classed along with eukaryotic motile cilia as undulipodia to emphasize their distinctive wavy appendage role in cellular function or motility. Primary cilia are immotile, and are not undulipodia, they have a structurally different 9+0 axoneme rather than the 9+2 axoneme found in both flagella and motile cilia undulipodia, the bacterial flagellum is made up of the protein flagellin. Its shape is a 20-nanometer-thick hollow tube and it is helical and has a sharp bend just outside the outer membrane, this hook allows the axis of the helix to point directly away from the cell. A shaft runs between the hook and the body, passing through protein rings in the cells membrane that act as bearings. Gram-positive organisms have two of these basal body rings, one in the layer and one in the plasma membrane. The filament ends with a capping protein, the flagellar filament is the long, helical screw that propels the bacterium when rotated by the motor, through the hook. Each protofilament is a series of protein chains. However, Campylobacter jejuni has seven protofilaments, the basal body has several traits in common with some types of secretory pores, such as the hollow, rod-like plug in their centers extending out through the plasma membrane. The bacterial flagellum is driven by an engine made up of protein
11.
Amblypygi
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Amblypygi is an ancient order of arachnid chelicerate arthropods also known as whip spiders and tailless whip scorpions. The name amblypygid means blunt rump, a reference to a lack of the flagellum that is seen in whip scorpions. Amblypygids possess no silk glands or venomous fangs and they rarely bite if threatened, but can grab fingers with their pedipalps, resulting in thorn-like puncture injuries. As of 2016,5 families,17 genera and around 155 species had been discovered and described. They are found in tropical and subtropical regions worldwide, they are found in warm and humid environments and like to stay protected and hidden within leaf litter, caves. Some species are subterranean, all are nocturnal, fossilized amblypygids have been found dating back to the Carboniferous period, such as Graeophonus. Amblypygids range from 5 to 70 centimetres in legspan and their bodies are broad and highly flattened, with a solid carapace and a segmented abdomen. Most species have eight eyes, a pair of eyes at the front of the carapace above the chelicerae and 2 smaller clusters of three eyes each further back on each side. Amblypygids have raptorial pedipalps modified for grabbing and retaining prey, much like those of a mantis, the first pair of legs act as sensory organs and are not used for walking. The sensory legs are thin and elongate, have numerous sensory receptors. Amblypygids have eight legs, but use only six for walking, often in a crab-like, the front pair of legs are modified for use as antennae-like feelers, with many fine segments giving the appearance of a whip. Courtship involves the male depositing stalked spermatophores, which have one or more sperm masses at the tip, onto the ground and she gathers the sperm and lays fertilized eggs into a sac carried under the abdomen. When the young hatch, they climb up onto the mothers back, some species of amblypygids, particularly Phrynus marginemaculatus and Damon diadema, may be among the few examples of arachnids that exhibit social behavior. The ultimate function of social behavior remains unknown. Amblypygids hold territories that they defend from other individuals, the amblypygid diet mostly consists of arthropod prey, but this opportunistic predator has also been observed feeding on vertebrates. Before, during and after molting they generally do not feed, like any other arachnid, an amblypygid will molt several times during its life
12.
Millipede
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Each double-legged segment is a result of two single segments fused together. Most millipedes have very elongated cylindrical or flattened bodies with more than 20 segments, while pill millipedes are shorter, although the name millipede derives from the Latin for thousand feet, no known species has 1,000, the record of 750 legs belongs to Illacme plenipes. Most millipedes are slow-moving detritivores, eating decaying leaves and other plant matter. Some eat fungi or suck plant fluids, and a minority are predatory. Millipedes are generally harmless to humans, although some can become household or garden pests, most millipedes defend themselves with a variety of chemicals secreted from pores along the body, although the tiny bristle millipedes are covered with tufts of detachable bristles. Reproduction in most species is carried out by modified male legs called gonopods, first appearing in the Silurian period, millipedes are some of the oldest known land animals. Some members of prehistoric groups grew to over 2 m, the largest modern species reach lengths of 27 to 38 cm. The longest extant species is the giant African millipede, among myriapods, millipedes have traditionally been considered most closely related to the tiny pauropods, although some molecular studies challenge this relationship. Millipedes can be distinguished from the similar but only distantly related centipedes, which move rapidly, are carnivorous. The scientific study of millipedes is known as diplopodology, and a scientist who studies them is called a diplopodologist. The scientific name Diplopoda comes from the Ancient Greek words διπλοῦς, double and ποδός, foot, the common name millipede is a compound word formed from the Latin roots mille and ped. The term millipede is widespread in popular and scientific literature, but among North American scientists, other vernacular names include thousand-legger or simply diplopod. The science of biology and taxonomy is called diplopodology, the study of diplopods. Approximately 12,000 millipede species have been described, estimates of the true number of species on earth range from 15,000 to as high as 80,000. Few species of millipede are at all widespread, they have very poor dispersal abilities, depending as they do on terrestrial locomotion and these factors have favoured genetic isolation and rapid speciation, producing many lineages with restricted ranges. The living members of the Diplopoda are divided into sixteen orders in two subclasses, the basal subclass Penicillata contains a single order, Polyxenida. The higher-level classification of millipedes is presented below, based on Shear,2011, the placement and positions of extinct groups known only from fossils is tentative and not fully resolved. After each name is listed the author citation, the name of the person who coined the name or defined the group, early forms probably ate mosses and primitive vascular plants
