1.
Computer mouse
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A computer mouse is a pointing device that detects two-dimensional motion relative to a surface. This motion is typically translated into the motion of a pointer on a display, physically, a mouse consists of an object held in ones hand, with one or more buttons. Mice often also other elements, such as touch surfaces and wheels. The earliest known publication of the mouse as referring to a computer pointing device is in Bill Englishs July 1965 publication. The plural for the rodent is always mice in modern usage. The plural of a mouse is mouses and mice according to most dictionaries. The first recorded usage is mice, the online Oxford Dictionaries cites a 1984 use. The trackball, a pointing device, was invented in 1944 by Ralph Benjamin as part of a World War II-era fire-control radar plotting system called Comprehensive Display System. Benjamin was then working for the British Royal Navy Scientific Service, Benjamins project used analog computers to calculate the future position of target aircraft based on several initial input points provided by a user with a joystick. Benjamin felt that a more elegant input device was needed and invented what they called a ball for this purpose. The device was patented in 1947, but only a prototype using a ball rolling on two rubber-coated wheels was ever built, and the device was kept as a military secret. Another early trackball was built by British electrical engineer Kenyon Taylor in collaboration with Tom Cranston, Taylor was part of the original Ferranti Canada, working on the Royal Canadian Navys DATAR system in 1952. DATAR was similar in concept to Benjamins display, the trackball used four disks to pick up motion, two each for the X and Y directions. When the ball was rolled, the pickup discs spun and contacts on their outer rim made periodic contact with wires, by counting the pulses, the physical movement of the ball could be determined. A digital computer calculated the tracks and sent the data to other ships in a task force using pulse-code modulation radio signals. This trackball used a standard Canadian five-pin bowling ball and it was not patented, since it was a secret military project. Douglas Engelbart of the Stanford Research Institute has been credited in published books by Thierry Bardini, Paul Ceruzzi, Howard Rheingold, Engelbart was also recognized as such in various obituary titles after his death in July 2013. That November, while attending a conference on computer graphics in Reno, Nevada, Engelbart began to ponder how to adapt the underlying principles of the planimeter to X-Y coordinate input
2.
House mouse
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The house mouse is a small mammal of the order Rodentia, characteristically having a pointed snout, small rounded ears, and a long naked or almost hairless tail. It is one of the most numerous species of the genus Mus, although a wild animal, the house mouse mainly lives in association with humans. The house mouse has been domesticated as the pet or fancy mouse, and as the laboratory mouse, the complete mouse reference genome was sequenced in 2002. Laboratory mice derived from the mouse are by far the most common mammalian species used in genetically engineered models for scientific research. House mice have an body length of 7. 5–10 cm. The weight is typically 40–45 g, in the wild they vary in colour from light to dark agouti, but domesticated fancy mice and laboratory mice are produced in many colors ranging from white to champagne to black. They have short hair and some, but not all, sub-species have a light belly, the ears and tail have little hair. The hind feet are short compared to Apodemus mice, only 15–19 mm long, the voice is a high-pitched squeak. House mice thrive under a variety of conditions, they are found in and around homes and commercial structures, as well as in open fields, newborn males and females can be distinguished on close examination as the anogenital distance in males is about double that of the female. From the age of about 10 days, females have five pairs of mammary glands, when sexually mature, the most striking and obvious difference is the presence of testicles on the males. These are large compared to the rest of the body and can be retracted into the body, tail length varies according to the environmental temperature of the mouse during postnatal development, so mice living in colder regions tend to have shorter tails. In addition to the regular pea-sized thymus organ in the chest, mice are mammals of the Glires clade, which means they are amongst the closest relatives of humans other than lagomorphs, treeshrews, flying lemurs and other primates. Some populations are hybrids of different subspecies, including the Japanese house mouse, mice are good jumpers, climbers, and swimmers, and are generally considered to be thigmotactic, i. e. usually attempts to maintain contact with vertical surfaces. Mice are mostly crepuscular or nocturnal, they are averse to bright lights, the average sleep time of a captive house mouse is reported to be 12.5 hours per day. They live in a variety of hidden places near food sources. Mice are territorial, and one dominant male usually lives together with several females, dominant males respect each others territories and normally enter anothers territory only if it is vacant. If two or more males are housed together in a cage, they become aggressive unless they have been raised together from birth. House mice primarily feed on plant matter, but are omnivorous and they eat their own faeces to acquire nutrients produced by bacteria in their intestines
3.
Rodent
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Rodents are mammals of the order Rodentia, which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all species are rodents, they are found in vast numbers on all continents except Antarctica. They are the most diversified mammalian order and live in a variety of terrestrial habitats, Species can be arboreal, fossorial, or semiaquatic. Well-known rodents include mice, rats, squirrels, prairie dogs, porcupines, beavers, guinea pigs, hamsters, and capybaras. Other animals such as rabbits, hares, and pikas, whose incisors also grow continually, were included with them, but are now considered to be in a separate order. Nonetheless, Rodentia and Lagomorpha are sister groups, sharing a most recent common ancestor, most rodents are small animals with robust bodies, short limbs, and long tails. They use their incisors to gnaw food, excavate burrows. Most eat seeds or other plant material, but some have more varied diets and they tend to be social animals and many species live in societies with complex ways of communicating with each other. Mating among rodents can vary from monogamy, to polygyny, to promiscuity, many have litters of underdeveloped, altricial young, while others are precocial at birth. The rodent fossil record back to the Paleocene on the supercontinent of Laurasia. Rodents greatly diversified in the Eocene, as spread across continents. Rodents reached both South America and Madagascar from Africa, and were the only placental mammals to reach. Rodents have been used as food, for clothing, as pets, some species, in particular the brown rat, the black rat, and the house mouse, are serious pests, eating and spoiling food stored by humans, and spreading diseases. The distinguishing feature of the rodents is their pairs of continuously growing and these incisors have thick layers of enamel on the front and little enamel on the back. Because they do not stop growing, the animal must continue to wear them down so that they do not reach and pierce the skull. As the incisors grind against each other, the softer dentine on the rear of the teeth wears away, most species have up to 22 teeth with no canines or anterior premolars. A gap, or diastema, occurs between the incisors and the teeth in most species. This allows rodents to suck in their cheeks or lips to shield their mouth and throat from wood shavings and other inedible material, chinchillas and guinea pigs have a high-fiber diet, their molars have no roots and grow continuously like their incisors
4.
Pet
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A pet or companion animal is an animal kept primarily for a persons company, protection, or entertainment rather than as a working animal, sport animal, livestock, or laboratory animal. Popular pets are often noted for their appearances and their loyal or playful personalities. Pets provide their owners physical and emotional benefits, walking a dog can supply both the human and pet with exercise, fresh air, and social interaction. Pets can give companionship to elderly adults who do not have social interaction with other people. There is an approved class of therapy animals, mostly dogs or cats. Pet therapy utilizes trained animals and handlers to achieve physical, social, cognitive. Some scholars and animal rights organizations have raised concern over pet-keeping with regards to the autonomy, States, cities, and towns in Western nations commonly enact local ordinances to limit the number or kind of pets a person may keep personally or for business purposes. Prohibited pets may be specific to certain breeds, they may apply to general categories of animals, additional or different maintenance rules and regulations may also apply. Condominium associations and owners of properties also commonly limit or forbid tenants keeping of pets. The keeping of animals as pets can cause concerns with regard to animal rights, pets have commonly been considered private property, owned by individual persons. However, many legal protections have existed with the intention of safeguarding pets well-being, since the year 2000, a small but increasing number of jurisdictions in North America have enacted laws redefining pets owners as guardians. Intentions have been characterized as simply changing attitudes and perceptions to working toward legal personhood for pets themselves, some veterinarians and breeders have opposed these moves. The question of legal status can arise with concern to purchase or adoption, custody, divorce, estate and inheritance, injury, damage. There are approximately 86.4 million pet cats in the United States, approximately 78.2 million pet dogs in the United States, the two most popular pets in most Western countries have been cats and dogs. In the United States, a 2007–2008 survey showed that dog-owning households outnumbered those owning cats, the same was true for 2011. In 2013, pets outnumbered children four to one in the United States, for a small to medium-size dog, the total cost over a dogs lifetime is about $7,240 to $12,700. For an indoor cat, the total cost over a lifetime is about $8,620 to $11,275. People most commonly get pets for companionship, to protect a home or property, the most common reasons for not owning a pet are lack of time, lack of suitable housing, and lack of ability to care for the pet when traveling
5.
Mouse
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A mouse is a small rodent characteristically having a pointed snout, small rounded ears, a body-length scaly tail and a high breeding rate. The best known species is the common house mouse. It is also a popular pet, in some places, certain kinds of field mice are locally common. They are known to invade homes for food and shelter, domestic mice sold as pets often differ substantially in size from the common house mouse. This is attributable both to breeding and to different conditions in the wild, the most well known strain, the white lab mouse, has more uniform traits that are appropriate to its use in research. The American white-footed mouse and the mouse, as well as other common species of mouse-like rodents around the world. These, however, are in other genera, cats, wild dogs, foxes, birds of prey, snakes and even certain kinds of arthropods have been known to prey heavily upon mice. Nevertheless, because of its adaptability to almost any environment. Mice, in contexts, can be considered vermin which are a major source of crop damage, causing structural damage. In North America, breathing dust that has come in contact with mouse excrement has been linked to hantavirus, primarily nocturnal animals, mice compensate for their poor eyesight with a keen sense of hearing, and rely especially on their sense of smell to locate food and avoid predators. Mice build intricate burrows in the wild and these burrows typically have long entrances and are equipped with escape tunnels or routes. In at least one species, the design of a burrow is a genetic trait. Breeding onset is at about 50 days of age in females and males, although females may have their first estrus at 25–40 days. Mice are polyestrous and breed year round, ovulation is spontaneous, the duration of the estrous cycle is 4–5 days and estrus itself lasts about 12 hours, occurring in the evening. Vaginal smears are useful in timed matings to determine the stage of the estrous cycle, mating is usually nocturnal and may be confirmed by the presence of a copulatory plug in the vagina up to 24 hours post-copulation. The presence of sperm on a smear is also a reliable indicator of mating. Female mice housed together tend to go into anestrus and do not cycle, if exposed to a male mouse or the pheromones of a male mouse, most of the females will go into estrus in about 72 hours. This synchronization of the cycle is known as the Whitten effect
6.
Rat
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Rats are various medium-sized, long-tailed rodents of the superfamily Muroidea. True rats are members of the genus Rattus, the most important of which to humans are the black rat, Rattus rattus, many members of other rodent genera and families are also referred to as rats, and share many characteristics with true rats. Rats are typically distinguished from mice by their size, generally, when someone discovers a large muroid rodent, its common name includes the term rat, while if it is smaller, the name includes the term mouse. The muroid family is broad and complex, and the common terms rat, scientifically, the terms are not confined to members of the Rattus and Mus genera, for example, the pack rat and cotton mouse. The best-known rat species are the black rat and the brown rat, the group is generally known as the Old World rats or true rats, and originated in Asia. Rats are bigger than most Old World mice, which are their relatives, the term rat is also used in the names of other small mammals which are not true rats. Examples include the North American pack rats, a number of species loosely called kangaroo rats, Rats such as the bandicoot rat are murine rodents related to true rats, but are not members of the genus Rattus. Male rats are called bucks, unmated females are called does, pregnant or parent females are called dams, a group of rats is referred to as a mischief. The common species are opportunistic survivors and often live with and near humans, therefore and they may cause substantial food losses, especially in developing countries. However, the distributed and problematic commensal species of rats are a minority in this diverse genus. Many species of rats are island endemics and some have become endangered due to loss or competition with the brown. Wild rodents, including rats, can carry many different zoonotic pathogens, such as Leptospira, Toxoplasma gondii, another zoonotic disease linked to the rat is the foot-and-mouth disease. The average lifespan of any given rat depends on species is being discussed. The black and brown rats diverged from other Old World rats during the beginning of the Pleistocene in the forests of Asia, specially bred rats have been kept as pets at least since the late 19th century. Pet rats are typically variants of the brown rat, but black rats. Pet rats behave differently from their wild counterparts depending on how many generations they have kept as pets. Pet rats do not pose any more of a risk than pets such as cats or dogs. Tamed rats are generally friendly and can be taught to perform selected behaviors, in 1895, Clark University in Worcester, Massachusetts established a population of domestic albino brown rats to study the effects of diet and for other physiological studies
7.
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
8.
Cat
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The domestic cat is a small, typically furry, carnivorous mammal. They are often called house cats when kept as pets or simply cats when there is no need to distinguish them from other felids. Cats are often valued by humans for companionship and for their ability to hunt vermin, there are more than 70 cat breeds, though different associations proclaim different numbers according to their standards. Cats are similar in anatomy to the felids, with a strong flexible body, quick reflexes, sharp retractable claws. Cat senses fit a crepuscular and predatory ecological niche, cats can hear sounds too faint or too high in frequency for human ears, such as those made by mice and other small animals. They can see in near darkness, like most other mammals, cats have poorer color vision and a better sense of smell than humans. Cats, despite being solitary hunters, are a species and cat communication includes the use of a variety of vocalizations. Cats have a high breeding rate, under controlled breeding, they can be bred and shown as registered pedigree pets, a hobby known as cat fancy. Failure to control the breeding of pet cats by neutering, as well as the abandonment of former household pets, has resulted in numbers of feral cats worldwide. In certain areas outside cats native range, this has contributed, along with destruction and other factors. Cats have been known to extirpate a bird species within specific regions, a genetic study in 2007 concluded that domestic cats are descended from Near Eastern wildcats, having diverged around 8,000 BC in the Middle East. As of a 2007 study, cats are the second most popular pet in the US by number of pets owned, in a 2010 study they were ranked the third most popular pet in the UK, after fish and dogs, with around 8 million being owned. The domestic cat is believed to have evolved from the Near Eastern wildcat, the felids are a rapidly evolving family of mammals that share a common ancestor only 10–15 million years ago and include lions, tigers, cougars and many others. Within this family, domestic cats are part of the genus Felis, members of the genus are found worldwide and include the jungle cat of southeast Asia, European wildcat, African wildcat, the Chinese mountain cat, and the Arabian sand cat, among others. The domestic cat was first classified as Felis catus by Carl Linnaeus in the 10th edition of his Systema Naturae published in 1758, because of modern phylogenetics, domestic cats are usually regarded as another subspecies of the wildcat, F. silvestris. This has resulted in mixed usage of the terms, as the cat can be called by its subspecies name. Wildcats have also referred to as various subspecies of F. catus, but in 2003. The most common name in use for the cat remains F. catus
9.
Dog
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The domestic dog is a member of genus Canis that forms part of the wolf-like canids, and is the most widely abundant carnivore. The dog and the extant gray wolf are sister taxa, with modern wolves not closely related to the wolves that were first domesticated, the dog was the first domesticated species and has been selectively bred over millennia for various behaviors, sensory capabilities, and physical attributes. Their long association with humans has led dogs to be attuned to human behavior. Dogs vary widely in shape, size and colours, dogs perform many roles for people, such as hunting, herding, pulling loads, protection, assisting police and military, companionship and, more recently, aiding handicapped individuals. This influence on society has given them the sobriquet mans best friend. The term domestic dog is used for both domesticated and feral varieties. The English word dog comes from Middle English dogge, from Old English docga, the term may possibly derive from Proto-Germanic *dukkōn, represented in Old English finger-docce. The word also shows the familiar petname diminutive -ga also seen in frogga frog, picga pig, stagga stag, wicga beetle, worm, the term dog may ultimately derive from the earliest layer of Proto-Indo-European vocabulary. In 14th-century England, hound was the word for all domestic canines, and dog referred to a subtype of hound. It is believed this dog type was so common, it became the prototype of the category hound. By the 16th century, dog had become the general word, the word hound is ultimately derived from the Proto-Indo-European word *kwon-, dog. This semantic shift may be compared with in German, where the corresponding words Dogge, a male canine is referred to as a dog, while a female is called a bitch. The father of a litter is called the sire, and the mother is called the dam, the process of birth is whelping, from the Old English word hwelp, the modern English word whelp is an alternate term for puppy. A litter refers to the offspring at one birth which are called puppies or pups from the French poupée, doll. The term dog typically is applied both to the species as a whole, and any male member of the same. An adult female is a bitch, in some countries, especially in North America, dog is used instead due to the vulgar connotation of bitch. An adult male capable of reproduction is a stud, an adult female capable of reproduction is a brood bitch, or brood mother. Immature males or females are pups or puppies, a group of pups from the same gestation period is a litter
10.
Fox
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Foxes are small-to-medium-sized, omnivorous mammals belonging to several genera of the family Canidae. Foxes are slightly smaller than a domestic dog, with a flattened skull, upright triangular ears, a pointed, slightly upturned snout. Twelve species belong to the group of Vulpes genus of true foxes. Foxes live on every continent except Antarctica, by far the most common and widespread species of fox is the red fox with about 47 recognized subspecies. The global distribution of foxes, together with their reputation for cunning, has contributed to their prominence in popular culture and folklore in many societies around the world. The hunting of foxes with packs of hounds, long an established pursuit in Europe, the word fox comes from Old English, which derived from Proto-Germanic *fuhsaz. This in turn derives from Proto-Indo-European *puḱ-, meaning ’thick-haired, tail’. Male foxes are known as dogs, tods or reynards, females as vixens, a group of foxes is referred to as a skulk, leash, or earth. Foxes are generally smaller than members of the family Canidae such as wolves, jackals. For example, in the largest species, the red fox, males weigh on average between 4.1 and 8.7 kg, while the smallest species, the fennec fox, weighs just 0.7 to 1.6 kg. Fox-like features typically include a face, pointed ears, an elongated rostrum. Foxes are digitigrade, and thus, walk on their toes, unlike their dog relatives, foxes have partially retractable claws. Fox vibrissae, or whiskers, are black, the whiskers on the muzzle, mystaciae vibrissae, average 100-110mm long, while the whiskers everywhere else on the head average to be shorter in length. Whiskers are also on the forelimbs and average 40mm long, pointing downward and backward, other physical characteristics vary according to habitat and adaptive significance. Fox species differ in fur color, length, and density, coat colors range from pearly white to black and white to black flecked with white or grey on the underside. Fennec foxes, for example, have ears and short fur to aid in keeping the body cool. Arctic foxes, on the hand, have tiny ears and short limbs as well as thick, insulating fur. Red foxes, by contrast, have a typical auburn pelt, a foxs coat color and texture may vary due to the change in seasons, fox pelts are richer and denser in the colder months and lighter in the warmer months
11.
Bird of prey
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Bird of prey or predatory bird, also known as raptors, refers to several species of birds that hunt and feed on rodents and other small animals. The term raptor is derived from the Latin word rapere, meaning to seize or take by force and these birds are characterized by keen vision that allows them to detect their prey during flight and powerful talons and beaks. Taken literally, the bird of prey has a wide meaning that includes many birds that hunt and feed on animals. In ornithology, the definition for bird of prey has a meaning, birds that have very good eyesight for finding food, strong feet for holding food. Most birds of prey also have strong curved talons for catching or killing prey, Birds of prey generally prey on vertebrates, which are usually quite large relative to the size of the bird. Most also eat carrion, at least occasionally, and vultures, the order Accipitriformes is believed to have originated 44 million years ago when it split from the common ancestor of the secretarybird and the accipitrid species. The phylogeny of Accipitriformes is complex and difficult to unravel, widespread paraphylies were observed in many phylogenetic studies. More recent and detailed studies show similar results, however, according to the findings of a 2014 study, the sister relationship between larger clades of Accipitriformes was well supported. The diurnal birds of prey are formally classified into five families of two orders, the Cathartidae are sometimes placed separately in an enlarged stork family, Ciconiiformes, and may be raised to an order of their own, Cathartiiformes. The secretary bird and/or osprey are sometimes listed as subfamilies of Acciptridae, Sagittariinae and Pandioninae, australias letter-winged kite is a member of the family Accipitridae, although it is a nocturnal bird. He placed all birds of prey into an order, Accipitres, subdividing this into four genera, Vultur, Falco, Strix. This approach was followed by subsequent authors such as Gmelin, Latham, louis Pierre Veillot used additional ranks, order, tribe, family, genus, species. Birds of prey were divided into diurnal and nocturnal tribes, the owls remained monogeneric, thus Veillots families were similar to the Linnaean genera, with the difference that shrikes were no longer included amongst the birds of prey. In addition to the original Vultur and Falco, Veillot adopted four genera from Savigny, Phene, Haliæetus, Pandion and he also introduced five new genera of vultures and eleven new genera of accipitrines. The common names for birds of prey are based on structure. Eagles tend to be large birds with long, broad wings, booted eagles have legs and feet feathered to the toes and build very large stick nests. Ospreys, a species found worldwide that specializes in catching fish. Kites have long wings and relatively weak legs and they spend much of their time soaring
12.
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
