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.
Insect
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Insects are a class of hexapod invertebrates within the arthropod phylum that have a chitinous exoskeleton, a three-part body, three pairs of jointed legs, compound eyes and one pair of antennae. They are the most diverse group of animals on the planet, including more than a million described species, the number of extant species is estimated at between six and ten million, and potentially represent over 90% of the differing animal life forms on Earth. Insects may be found in all environments, although only a small number of species reside in the oceans. The life cycles of insects vary but most hatch from eggs, insect growth is constrained by the inelastic exoskeleton and development involves a series of molts. The immature stages can differ from the adults in structure, habit and habitat, Insects that undergo 3-stage metamorphosis lack a pupal stage and adults develop through a series of nymphal stages. The higher level relationship of the Hexapoda is unclear, fossilized insects of enormous size have been found from the Paleozoic Era, including giant dragonflies with wingspans of 55 to 70 cm. The most diverse insect groups appear to have coevolved with flowering plants, adult insects typically move about by walking, flying or sometimes swimming. As it allows for rapid yet stable movement, many insects adopt a tripedal gait in which they walk with their legs touching the ground in alternating triangles, Insects are the only invertebrates to have evolved flight. Many insects spend at least part of their lives under water, with adaptations that include gills. Some species, such as water striders, are capable of walking on the surface of water, Insects are mostly solitary, but some, such as certain bees, ants and termites, are social and live in large, well-organized colonies. Some insects, such as earwigs, show maternal care, guarding their eggs, Insects can communicate with each other in a variety of ways. Male moths can sense the pheromones of female moths over great distances, other species communicate with sounds, crickets stridulate, or rub their wings together, to attract a mate and repel other males. Lampyridae in the beetle order communicate with light, humans regard certain insects as pests, and attempt to control them using insecticides and a host of other techniques. Some insects damage crops by feeding on sap, leaves or fruits, a few parasitic species are pathogenic. Some insects perform complex ecological roles, blow-flies, for example, help consume carrion, Many other insects are considered ecologically beneficial as predators and a few provide direct economic benefit. Silkworms and bees have been used extensively by humans for the production of silk and honey, in some cultures, people eat the larvae or adults of certain insects. Insect first appears documented in English in 1601 in Hollands translation of Pliny, translations of Aristotles term also form the usual word for insect in Welsh, Serbo-Croatian, Russian, etc. The evolutionary relationship of insects to other animal groups remains unclear, in the Pancrustacea theory, insects, together with Entognatha, Remipedia, and Cephalocarida, make up a natural clade labeled Miracrustacea
5.
Louse
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Louse is the common name for members of the order Phthiraptera, which contains nearly 5,000 species of wingless insect. Lice are obligate parasites, living externally on warm-blooded hosts which include species of bird and mammal, except for monotremes, pangolins, bats. Lice are vectors of diseases such as typhus, chewing lice live among the hairs or feathers of their host and feed on skin and debris, while sucking lice pierce the hosts skin and feed on blood and other secretions. They usually spend their life on a single host, cementing their eggs. The eggs hatch into nymphs, which three times before becoming fully grown, a process that takes about four weeks. Humans host three species of louse, the louse, the body louse and the pubic louse. The body louse has the smallest genome of any known insect, Lice were ubiquitous in human society until at least the Middle Ages. They appear in folktales, songs such as The Kilkenny Louse House and they commonly feature in the psychiatric disorder delusional parasitosis. A louse was one of the subjects of microscopy, appearing in Robert Hookes 1667 book. Humans host three different kinds of lice, head lice, body lice, and pubic lice, Lice infestations can be controlled with lice combs, and medicated shampoos or washes. Sucking lice are wingless insects ranging from 0.5 to 5 mm in length. They have narrow heads and oval, flattened bodies and they have no ocelli, and their compound eyes are reduced in size or absent. Their antennae are short with three to five segments, and their parts, which are retractable into their head, are adapted for piercing and sucking. There is a pump at the start of the gut. The mouthparts consist of a proboscis which is toothed, and a set of stylets arranged in a cylinder inside the proboscis, contaiing a salivary canal and a food canal. The thoracic segments are fused, the segments are separate. Chewing lice are also flattened and can be larger than sucking lice. They are similar to sucking lice in form but the head is wider than the thorax, there are no ocelli and the mouthparts are adapted for chewing
6.
Pediculus
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The body louse is a louse that infests humans. The condition of being infested with lice, body lice. Body lice are vectors for the transmission of the human diseases Epidemic typhus, Trench fever, Pediculus humanus humanus is indistinguishable in appearance from Pediculus humanus capitis but will interbreed only under laboratory conditions. In their natural state, they occupy different habitats and do not usually meet, in particular, body lice have evolved to attach their eggs to clothes, whereas head lice attach their eggs to the base of hairs. The life cycle of the body consists of three stages, egg, nymph, and adult. They are generally easy to see in the seams of a persons clothing, particularly around the waistline. They are oval and usually yellow to white in color, Body lice nits may take 1–2 weeks to hatch. A nymph is a louse that hatches from the nit. A nymph looks like an adult body louse, but is smaller, nymphs mature into adults about 9–12 days after hatching. To live, it must feed on blood, the adult body louse is about the size of a sesame seed, has six legs, and is tan to greyish-white. To live, lice must feed on blood, if separated from their hosts, lice die. The body louse diverged from the head louse at around 100,000 years ago, Body lice were first described by Carl Linnaeus in the 10th edition of Systema Naturae. The human body louse had its genome sequenced in 2010, list of parasites Body and head lice on the UF / IFAS Featured Creatures Web site
7.
Charles De Geer
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Baron Charles de Geer was a Swedish industrialist and entomologist. De Geer, who came from a family with strong Dutch connections and he returned to Sweden at the age of 19. He had inherited the manor and important iron-works of Leufsta in Uppland from his childless uncle and namesake. Ever since he had received a present of some silk worms at the age of eight, he had an interest in entomology and his major work was the Mémoires pour servir à lhistoire des insectes. He was elected a member of the Royal Swedish Academy of Sciences already in 1739, at the age of nineteen, and he is buried with his spouse in Uppsala Cathedral. His collections of insects were donated to the Academy of Sciences and he left a library at Leufsta which, among other things, included the papers of Olaus Rudbeck and an important collection of 18th century sheet music. The Leufsta library was acquired by Uppsala University Library in 1986 after a donation by Katarina Crafoord, De Geer was a great admirer of Réaumur. Hence his modelling Mémoires pour servir à lhistoire des insectes on Réaumur’s work of the same title and it, too, is in French, similarly in large quarto and with the same decorations. The Mémoires deal with 1,466 species, treating life histories, food and reproduction based on careful, patient investigation, in nomenclature De Geer was less progressive, Volume 1 of the Mémoires was too early to employ the binomial system invented by his fellow Swede Linnaeus. Volume 2 did not use it, but in Volumes 3 to Volume 7 the Linnean system was employed. However, for many species De Geer used two or more words for a name, such as Aphis betulae nigro punctata, these names were not binomial in the Linnean sense. He also proposed different names for species which had previously been named and described by Linnaeus. It seems that using Linnean names was a concession to usage as in the 1760s and 1770s the Linnean system became increasingly employed, tal om nyttan, som Insecterne och deras skärskådande, tilskynda oss. Mémoires pour servir à lhistoire des insectes, müller & Raspe, Leipzig, Nürnberg 1776-83 p. m. Genera et species insectorum. Crusium, Leipzig 1783 p. m. Lizars, Edinburgh 1840, some reflections on the history of systematic Dipterology. Dipterists Digest, Series 2,2, 49-70, degeer’s insect collection, without the original labels and not in the original cabinet may be found at the Swedish Museum of Natural History. Charles de Geer Mémoires pour servir à lhistoire des insectes, digital facsimile at the Gallica website. Gaedike, R. Groll, E. K. & Taeger, A.2012, Bibliography of the literature from the beginning until 1863
8.
Synonym (taxonomy)
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For example, Linnaeus was the first to give a scientific name to the Norway spruce, which he called Pinus abies. This name is no longer in use, it is now a synonym of the current scientific name which is Picea abies, unlike synonyms in other contexts, in taxonomy a synonym is not interchangeable with the name of which it is a synonym. In taxonomy, synonyms are not equals, but have a different status, for any taxon with a particular circumscription, position, and rank, only one scientific name is considered to be the correct one at any given time. A synonym cannot exist in isolation, it is always an alternative to a different scientific name, given that the correct name of a taxon depends on the taxonomic viewpoint used a name that is one taxonomists synonym may be another taxonomists correct name. Synonyms may arise whenever the same taxon is described and named more than once, independently. They may also arise when existing taxa are changed, as when two taxa are joined to one, a species is moved to a different genus. To the general user of scientific names, in such as agriculture, horticulture, ecology, general science. A synonym is a name that was used as the correct scientific name but which has been displaced by another scientific name. Thus Oxford Dictionaries Online defines the term as a name which has the same application as another. In handbooks and general texts, it is useful to have mentioned as such after the current scientific name. Synonyms used in this way may not always meet the strict definitions of the synonym in the formal rules of nomenclature which govern scientific names. Changes of scientific name have two causes, they may be taxonomic or nomenclatural, a name change may be caused by changes in the circumscription, position or rank of a taxon, representing a change in taxonomic, scientific insight. A name change may be due to purely nomenclatural reasons, that is, based on the rules of nomenclature, the earliest such name is called the senior synonym, while the later name is the junior synonym. One basic principle of zoological nomenclature is that the earliest correctly published name, synonyms are important because if the earliest name cannot be used, then the next available junior synonym must be used for the taxon. Objective synonyms refer to taxa with the type and same rank. For example, John Edward Gray published the name Antilocapra anteflexa in 1855 for a species of pronghorn, however, it is now commonly accepted that his specimen was an unusual individual of the species Antilocapra americana published by George Ord in 1815. Ords name thus takes precedence, with Antilocapra anteflexa being a subjective synonym. Objective synonyms are common at the level of genera, because for various reasons two genera may contain the type species, these are objective synonyms
9.
Parasitism
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In biology/ecology, parasitism is a non-mutual relationship between species, where one species, the parasite, benefits at the expense of the other, the host. Traditionally parasite referred primarily to organisms visible to the naked eye, Parasites can be microparasites, which are typically smaller, such as protozoa, viruses, and bacteria. Examples of parasites include the plants mistletoe and cuscuta, and animals such as hookworms, unlike predators, parasites typically do not kill their host, are generally much smaller than their host, and will often live in or on their host for an extended period. Both are special cases of consumer-resource interactions, Parasites show a high degree of specialization, and reproduce at a faster rate than their hosts. Classic examples of parasitism include interactions between vertebrate hosts and tapeworms, flukes, the Plasmodium species, and fleas, parasitism differs from the parasitoid relationship in that parasitoids generally kill their hosts. Parasites reduce host biological fitness by general or specialized pathology, such as parasitic castration and impairment of secondary sex characteristics, Parasites increase their own fitness by exploiting hosts for resources necessary for their survival, e. g. food, water, heat, habitat, and transmission. Although parasitism applies unambiguously to many cases, it is part of a continuum of types of interactions between species, rather than an exclusive category, in many cases, it is difficult to demonstrate harm to the host. In others, there may be no apparent specialization on the part of the parasite, coined in English in 1611, the word parasitism comes from the Greek παρά + σιτισμός feeding, fattening. Parasites are classified based on their interactions with their hosts and on their life cycles, an obligate parasite is totally dependent on the host to complete its life cycle, while a facultative parasite is not. A direct parasite has one host while an indirect parasite has multiple hosts. For indirect parasites, there always be a definitive host. Parasites that live on the outside of the host, either on the skin or the outgrowths of the skin, are called ectoparasites and those that live inside the host are called endoparasites. Endoparasites can exist in one of two forms, intercellular parasites or intracellular parasites, intracellular parasites, such as protozoa, bacteria or viruses, tend to rely on a third organism, which is generally known as the carrier or vector. The vector does the job of transmitting them to the host, an example of this interaction is the transmission of malaria, caused by a protozoan of the genus Plasmodium, to humans by the bite of an anopheline mosquito. Those parasites living in a position, being half-ectoparasites and half-endoparasites, are called mesoparasites. An epiparasite is one that feeds on another parasite and this relationship is also sometimes referred to as hyperparasitism, exemplified by a protozoan living in the digestive tract of a flea living on a dog. Social parasites take advantage of interactions between members of social organisms such as ants, termites, and bumblebees, an extreme example of social parasitism is the ant species of Tetramorium inquilinum of the Alps, which spend their whole lives on the back of Tetramorium host ants. With tiny and deprecated bodies they have evolved for one single task, if they fall off, they most likely would not have the strength to climb back on top of another ant, and eventually they will die
10.
Human
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Modern humans are the only extant members of Hominina tribe, a branch of the tribe Hominini belonging to the family of great apes. Several of these hominins used fire, occupied much of Eurasia and they began to exhibit evidence of behavioral modernity around 50,000 years ago. In several waves of migration, anatomically modern humans ventured out of Africa, the spread of humans and their large and increasing population has had a profound impact on large areas of the environment and millions of native species worldwide. Humans are uniquely adept at utilizing systems of communication for self-expression and the exchange of ideas. Humans create complex structures composed of many cooperating and competing groups, from families. Social interactions between humans have established a wide variety of values, social norms, and rituals. These human societies subsequently expanded in size, establishing various forms of government, religion, today the global human population is estimated by the United Nations to be near 7.5 billion. In common usage, the word generally refers to the only extant species of the genus Homo—anatomically and behaviorally modern Homo sapiens. In scientific terms, the meanings of hominid and hominin have changed during the recent decades with advances in the discovery, there is also a distinction between anatomically modern humans and Archaic Homo sapiens, the earliest fossil members of the species. The English adjective human is a Middle English loanword from Old French humain, ultimately from Latin hūmānus, the words use as a noun dates to the 16th century. The native English term man can refer to the species generally, the species binomial Homo sapiens was coined by Carl Linnaeus in his 18th century work Systema Naturae. The generic name Homo is a learned 18th century derivation from Latin homō man, the species-name sapiens means wise or sapient. Note that the Latin word homo refers to humans of either gender, the genus Homo evolved and diverged from other hominins in Africa, after the human clade split from the chimpanzee lineage of the hominids branch of the primates. The closest living relatives of humans are chimpanzees and gorillas, with the sequencing of both the human and chimpanzee genome, current estimates of similarity between human and chimpanzee DNA sequences range between 95% and 99%. The gibbons and orangutans were the first groups to split from the leading to the humans. The splitting date between human and chimpanzee lineages is placed around 4–8 million years ago during the late Miocene epoch, during this split, chromosome 2 was formed from two other chromosomes, leaving humans with only 23 pairs of chromosomes, compared to 24 for the other apes. There is little evidence for the divergence of the gorilla, chimpanzee. Each of these species has been argued to be an ancestor of later hominins
11.
Blood
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Blood is a body fluid in humans and other animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells. In vertebrates, it is composed of blood cells suspended in blood plasma, plasma, which constitutes 55% of blood fluid, is mostly water, and contains dissipated proteins, glucose, mineral ions, hormones, carbon dioxide, and blood cells themselves. Albumin is the protein in plasma, and it functions to regulate the colloidal osmotic pressure of blood. The blood cells are red blood cells, white blood cells. The most abundant cells in blood are red blood cells. These contain hemoglobin, a protein, which facilitates oxygen transport by reversibly binding to this respiratory gas. In contrast, carbon dioxide is mostly transported extracellularly as bicarbonate ion transported in plasma, vertebrate blood is bright red when its hemoglobin is oxygenated and dark red when it is deoxygenated. Some animals, such as crustaceans and mollusks, use hemocyanin to carry oxygen, insects and some mollusks use a fluid called hemolymph instead of blood, the difference being that hemolymph is not contained in a closed circulatory system. In most insects, this blood does not contain oxygen-carrying molecules such as hemoglobin because their bodies are small enough for their system to suffice for supplying oxygen. Jawed vertebrates have an immune system, based largely on white blood cells. White blood cells help to resist infections and parasites, platelets are important in the clotting of blood. Arthropods, using hemolymph, have hemocytes as part of their immune system, Blood is circulated around the body through blood vessels by the pumping action of the heart. Medical terms related to blood often begin with hemo- or hemato- from the Greek word αἷμα for blood. In terms of anatomy and histology, blood is considered a form of connective tissue, given its origin in the bones. The average adult has a volume of roughly 5 litres. These blood cells consist of erythrocytes, leukocytes, and thrombocytes, by volume, the red blood cells constitute about 45% of whole blood, the plasma about 54. 3%, and white cells about 0. 7%. Whole blood exhibits non-Newtonian fluid dynamics, if all human hemoglobin were free in the plasma rather than being contained in RBCs, the circulatory fluid would be too viscous for the cardiovascular system to function effectively. One microliter of blood contains,4.7 to 6.1 million,4.2 to 5.4 million erythrocytes, Red blood cells contain the bloods hemoglobin, mature red blood cells lack a nucleus and organelles in mammals
12.
Host (biology)
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In biology, a host is an organism that harbors a parasitic, a mutual, or a commensal symbiont, typically providing nourishment and shelter. Examples include animals playing host to parasitic worms, cells harbouring a parasitic virus, more specifically in botany, a host plant supplies food resources and acts as a substrate for commensalist insects or other fauna. Guest is the term used for parasites, mutualists and commensals. The host range of a parasite is the collection of hosts that an organism can utilize as a partner, in the case of human parasites, the host range influences the epidemiology of the parasitism or disease. For instance, the production of antigenic shifts in Influenza A virus can result from pigs being infected with the virus from different hosts. This co-infection provides an opportunity for mixing of the viral genes between existing strains, thereby producing a new viral strain
13.
Chimpanzee
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Chimpanzees are one of the two species of the genus Pan, the other being the bonobo. Together with gorillas, they are the only exclusively African species of ape that are currently extant. Native to sub-Saharan Africa, both chimpanzees and bonobos are found in the Congo jungle. In addition, P. troglodytes is divided into four subspecies, based on genome sequencing, the two extant Pan species diverged around one million years ago. The most obvious differences are that chimpanzees are somewhat larger, more aggressive and male-dominated, while the bonobos are more gracile, peaceful and their hair is typically black or brown. Males and females differ in size and appearance, both chimps and bonobos are some of the most social great apes, with social bonds occurring among individuals in large communities. Fruit is the most important component of a diet, however, they will also eat vegetation, bark, honey, insects. They can live over 30 years in both the wild and captivity, Chimpanzees and bonobos are equally humanitys closest living relatives. As such, they are among the largest-brained, and most intelligent of primates, they use a variety of sophisticated tools and construct elaborate sleeping nests each night from branches and they have both been extensively studied for their learning abilities. There may even be distinctive cultures within populations, field studies of Pan troglodytes were pioneered by primatologist Jane Goodall. Both Pan species are considered to be endangered as human activities have caused declines in the populations. Threats to wild populations include poaching, habitat destruction. Several conservation and rehabilitation organisations are dedicated to the survival of Pan species in the wild, the first use of the name chimpanze is recorded in The London Magazine in 1738, glossed as meaning mockman in a language of the Angolans. The spelling chimpanzee is found in a 1758 supplement to Chambers Cyclopædia, the colloquialism chimp was most likely coined some time in the late 1870s. The common chimpanzee was named Simia troglodytes by Johann Friedrich Blumenbach in 1776, the species name troglodytes is a reference to the Troglodytae, an African people described by Greco-Roman geographers. Blumenbach first used it in his De generis humani varietate nativa liber in 1776, the genus name Pan was first introduced by Lorenz Oken in 1816. An alternative Theranthropus was suggested by Brookes 1828 and Chimpansee by Voigt 1831, troglodytes was not available, as it had been given as the name of a genus of wren in 1809. The International Commission on Zoological Nomenclature adopted Pan as the official name of the genus in 1895
14.
Hematophagic
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Hematophagy is the practice by certain animals of feeding on blood. Some intestinal nematodes, such as Ancylostomids, feed on blood extracted from the capillaries of the gut, and about 75 percent of all species of leeches, a free-living worm, are hematophagous. These hematophagous animals have mouth parts and chemical agents for penetrating vascular structures in the skin of hosts, mostly of mammals, birds and this type of feeding is known as phlebotomy. Once phlebotomy is performed, blood is acquired either by sucking action directly from the veins or capillaries, from a pool of escaped blood, scientists have developed anticoagulant medicines from studying substances in the saliva of several hematophagous species, such as leeches. Hematophagy is classified as either obligatory or facultative, obligatory hematophagous animals cant survive on any other food. Examples include Rhodnius prolixus, a South American assassin bug, and Cimex lectularius, facultative hematophages, meanwhile, acquire at least some portion of their nutrition from non-blood sources in at least one of the sexually mature forms. Examples of this include many species, such as Aedes aegypti, whose males feed on pollen. In anautogenous species, the female must consume blood in order to produce eggs, as a feeding practice, hematophagy has evolved independently in a number of arthropod, annelid, nematode and mammalian taxa. For example, Diptera have eleven families with hematophagous habits, about 14,000 species of arthropods are hematophagous, even including some genera that were not previously thought to be, such as moths of the genus Calyptra. Several complementary biological adaptations for locating the hosts have also evolved, such as physical or chemical detectors for sweat components, CO2, heat, light, movement. The phlebotomic action opens a channel for contamination of the host species with bacteria, viruses, louis encephalitis, tularemia, typhus, Rocky Mountain spotted fever, West Nile fever, Zika fever, and many others. Hematophagous organisms have been used by physicians for beneficial purposes, some doctors now use leeches to prevent the clotting of blood on some wounds following surgery or trauma. The anticoagulants in the laboratory-raised leeches saliva keeps fresh blood flowing to the site of an injury, actually preventing infection, in a recent study a genetically engineered drug called desmoteplase based on the saliva of Desmodus rotundus was shown to improve recovery in stroke patients. Many human societies also drink blood or use it to manufacture foodstuffs, cow blood mixed with milk, for example, is a mainstay food of the African Maasai. Marco Polo reported that Mongols drank blood from their horses if necessary, many places around the world eat Black pudding. Some societies, such as the Moche, had ritual hematophagy, as well as the Scythians, a people of Russia. Some religious rituals and symbols seemingly mirror hematophagy, such as in the transubstantiation of wine as the blood of Jesus Christ during Christian eucharist, psychiatric cases of patients performing hematophagy also exist. Sucking or licking ones own blood from a wound is also a human behavior
15.
Flea
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Fleas are small flightless insects that form the order Siphonaptera. As external parasites of mammals and birds, they live by consuming the blood of their hosts, adults are up to about 3 mm long and usually brown. Bodies flattened sideways enable them to move through their hosts fur or feathers and they lack wings, and have mouthparts adapted for piercing skin and sucking blood and hind legs adapted for jumping. The latter enable them to leap a distance of some 50 times their body length, larvae are worm-like with no limbs, they have chewing mouthparts and feed on organic debris. Over 2,500 species of fleas have been described worldwide, the Siphonaptera are most closely related to the snow scorpionflies, placing them within the endopterygote insect order Mecoptera. Fleas arose in the early Cretaceous, most likely as ectoparasites of mammals and marsupials, each species of flea is more or less a specialist on its host animal species, many species never breed on any other host, though some are less selective. The oriental rat flea, Xenopsylla cheopis, is a vector of Yersinia pestis, the disease was spread by rodents such as the black rat, which were bitten by fleas that then infected humans. Major outbreaks included the Plague of Justinian and the Black Death, both of which killed a sizeable fraction of the worlds population. Fleas appear in human culture in such forms as flea circuses, poems like John Donnes erotic The Flea, works of music such as by Modest Mussorgsky. Flea legs end in strong claws that are designed to grasp a host, unlike other insects, fleas do not possess compound eyes but instead only have simple eyespots with a single biconvex lens, some species lack eyes altogether. Their bodies are compressed, permitting easy movement through the hairs or feathers on the hosts body. The flea body is covered with hard plates called sclerites and these sclerites are covered with many hairs and short spines directed backward, which also assist its movements on the host. The tough body is able to withstand great pressure, likely an adaptation to survive attempts to eliminate them by scratching, fleas lay tiny, white, oval eggs. The larvae are small and pale, have bristles covering their bodies, lack eyes. The larvae feed on organic matter, especially the feces of mature fleas, adults feed only on fresh blood. Immediately before the jump, muscles contract and deform the resilin pad, to prevent premature release of energy or motions of the leg, the flea employs a catch mechanism. Early in the jump, the tendon of the primary jumping muscle passes slightly behind the coxa-trochanter joint, generating a torque which holds the joint closed with the leg close to the body. To trigger jumping, another muscle pulls the tendon forward until it passes the joint axis, generating the opposite torque to extend the leg, the actual take off has been shown by high-speed video to be from the tibiae and tarsi rather than from the trochantera
16.
Body louse
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The body louse is a louse that infests humans. The condition of being infested with lice, body lice. Body lice are vectors for the transmission of the human diseases Epidemic typhus, Trench fever, Pediculus humanus humanus is indistinguishable in appearance from Pediculus humanus capitis but will interbreed only under laboratory conditions. In their natural state, they occupy different habitats and do not usually meet, in particular, body lice have evolved to attach their eggs to clothes, whereas head lice attach their eggs to the base of hairs. The life cycle of the body consists of three stages, egg, nymph, and adult. They are generally easy to see in the seams of a persons clothing, particularly around the waistline. They are oval and usually yellow to white in color, Body lice nits may take 1–2 weeks to hatch. A nymph is a louse that hatches from the nit. A nymph looks like an adult body louse, but is smaller, nymphs mature into adults about 9–12 days after hatching. To live, it must feed on blood, the adult body louse is about the size of a sesame seed, has six legs, and is tan to greyish-white. To live, lice must feed on blood, if separated from their hosts, lice die. The body louse diverged from the head louse at around 100,000 years ago, Body lice were first described by Carl Linnaeus in the 10th edition of Systema Naturae. The human body louse had its genome sequenced in 2010, list of parasites Body and head lice on the UF / IFAS Featured Creatures Web site
17.
Subspecies
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In biological classification, subspecies is either a taxonomic rank subordinate to species, or a taxonomic unit in that rank. A subspecies cannot be recognized independently, a species will either be recognized as having no subspecies at all or at least two, in zoology, under the International Code of Zoological Nomenclature, the subspecies is the only taxonomic rank below that of species that can receive a name. In botany and mycology, under the International Code of Nomenclature for algae, fungi, in bacteriology and virology, under standard bacterial nomenclature and virus nomenclature, there are recommendations but not strict requirements for recognizing other important infraspecific ranks. A taxonomist decides whether to recognize a subspecies or not, the differences between subspecies are usually less distinct than the differences between species. In zoology, the International Code of Zoological Nomenclature accepts only one rank below that of species, other groupings, infrasubspecific entities do not have names regulated by the ICZN. Such forms have no official ICZN status, though they may be useful in describing altitudinal or geographical clines, pet breeds, transgenic animals, etc. While the scientific name of a species is a binomen, the name of a subspecies is a trinomen - a binomen followed by a subspecific name. A tigers binomen is Panthera tigris, so for a Sumatran tiger the trinomen is, for example, names published before 1992 in the rank of variety are taken to be names of subspecies. In botany, subspecies is one of many ranks below that of species, such as variety, subvariety, form, the subspecific name is preceded by subsp. or ssp. as Schoenoplectus californicus ssp. tatora. A botanical name consists of at most three parts, an infraspecific name includes the species binomial, and one infraspecific epithet, such as subspecies or variety. For example, Motacilla alba alba is the subspecies of the white wagtail. The subspecies name that repeats the name is referred to in botanical nomenclature as the subspecies autonym. When zoologists disagree over whether a population is a subspecies or a full species. A subspecies is a rank below species – the only recognized rank in the zoological code. Botanists and mycologists have the choice of ranks lower than subspecies, such as variety or form, in biological terms, rather than in relation to nomenclature, a polytypic species has two or more subspecies, races, or more generally speaking, populations that need a separate description. These are separate groups that are distinct from one another and do not generally interbreed. These subspecies, races, or populations, can be named as subspecies by zoologists, a monotypic species has no distinct population or races, or rather one race comprising the whole species. A taxonomist would not name a subspecies within such a species, monotypic species can occur in several ways, All members of the species are very similar and cannot be sensibly divided into biologically significant subcategories
18.
Crab louse
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The crab louse is an insect that is an obligate ectoparasite of humans, feeding exclusively on blood. The crab louse usually is found in the pubic hair. Although the louse cannot jump, it can live in other areas of the body that are covered with coarse hair. Humans are the known hosts of the crab louse, although a closely related species, Pthirus gorillae. The human parasite diverged from Pthirus gorillae approximately 3.3 million years ago, and is distantly related to the genus Pediculus. An adult crab louse is about 1. 3–2 mm long, another distinguishing feature is that the rearmost two pairs of legs of a crab louse are much thicker than the front legs and have large claws. The eggs of the crab louse are laid usually on the hairs of the genital and perianal regions of the human body. Crab lice may also be found on areas of the body that have coarse and relatively sparse coverings of hair, such as the beard, moustache, eyelashes. They do not generally occur on the hair of the scalp. The female lays three eggs a day. The eggs take 6–8 days to hatch, and there are three stages which together take 10–17 days before the adult develops, making a total life cycle from egg to adult of 16–25 days. Adults live for up to 30 days, crab lice feed exclusively on blood, and take a blood meal 4–5 times daily. Infestations of crab lice are known as pediculosis pubis or phthiriasis pubis, infestation of the eyelashes is referred to as pediculosis ciliaris or phthiriasis palpebrarum. In some infestations, a characteristic grey-blue or slate coloration appears at the feeding site, crab lice usually infect a new host only by close contact between individuals, usually through sexual intercourse. Adults are more frequently infested than children, non-sexual transmissions may occur among family and roommates through the use of shared towels, clothing, beds or closets. They can only survive a short time away from the warmth and it has been suggested that an increasing percentage of humans removing their pubic hair has led to reduced crab louse populations in some parts of the world. Because the World Health Organization and other authorities do not record statistics for pubic louse infestation, there is virtually no hard data to support this supposition
19.
Immunity (medical)
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Immunity is the capability of multicellular organisms to resist harmful microorganisms from entering it. Immunity involves both specific and nonspecific components, the nonspecific components act as barriers or eliminators of a wide range of pathogens irrespective of their antigenic make-up. Other components of the immune system adapt themselves to each new disease encountered and are able to generate pathogen-specific immunity, an immune system may contain innate and adaptive components. The innate system in mammalians for example is composed of bone marrow cells that are programmed to recognise foreign substances. The adaptive system is composed of more advanced lymphatic cells that are programmed to recognise self substances, the reaction to foreign substances is etymologically described as inflammation, meaning to set on fire. The non-reaction to self substances is described as immunity, meaning to exempt or as immunotolerance, disease can arise when what is foreign cannot be eliminated or what is self is not spared. Innate immunity, also called native immunity, exists by virtue of an organisms constitution and it is divided into two types, Non-Specific innate immunity, a degree of resistance to all infections in general. Specific innate immunity, a resistance to a kind of microorganism only. As a result some races, specific individuals or breeds in agriculture do not suffer from certain infectious diseases, passive immunity is acquired through transfer of antibodies or activated T-cells from an immune host, it is short lived—usually lasting only a few months. The diagram below summarizes these divisions of immunity, humoral immunity is called active when the organism generates its own antibodies, and passive when antibodies are transferred between individuals or species. Similarly, cell mediated immunity is active when the organisms’ own T-cells are stimulated, the concept of immunity has intrigued mankind for thousands of years. Between the time of Hippocrates and the 19th century, when the foundations of the methods were laid. If someone were exposed to the miasma in a swamp, in evening air, or breathing air in a sickroom or hospital ward, the modern word immunity derives from the Latin immunis, meaning exemption from military service, tax payments or other public services. For no one was attacked a second time, or not with a fatal result. The term immunes, is found in the epic poem Pharsalia written around 60 B. C. by the poet Marcus Annaeus Lucanus to describe a North African tribes resistance to snake venom. In the treatise, Al Razi describes the presentation of smallpox. The first scientist who developed full theory of immunity was Ilya Mechnikov after he revealed phagocytosis in 1882, the birth of active immunotherapy may have begun with Mithridates VI of Pontus. To induce active immunity for snake venom, he recommended using a similar to modern toxoid serum therapy
20.
Sucking louse
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Sucking lice have around 500 species and represent the smaller of the two traditional suborders of lice. As opposed to the chewing lice, which are now divided among three suborders, the sucking lice are monophyletic. The Anoplura are all blood-feeding ectoparasites of mammals and they only occur on about 20% of all placentalian mammal species, and are unknown from several orders of mammals. They can cause localized skin irritations and are vectors of several blood-borne diseases, children appear particularly susceptible to attracting lice, possibly due to their fine hair. At least three species or subspecies of Anoplura are parasites of humans, the condition of being infested with sucking lice is called pediculosis. Pthirus pubis is the cause of the known as crabs
21.
Anatomical terms of location
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Standard anatomical terms of location deal unambiguously with the anatomy of animals, including humans. All vertebrates have the basic body plan – they are strictly bilaterally symmetrical in early embryonic stages. That is, they have left and right halves if divided down the centre. For these reasons, the directional terms can be considered to be those used in vertebrates. By extension, the terms are used for many other organisms as well. While these terms are standardized within specific fields of biology, there are unavoidable, sometimes dramatic, for example, differences in terminology remain a problem that, to some extent, still separates the terminology of human anatomy from that used in the study of various other zoological categories. The vertebrates and Craniata share a heritage and common structure. To avoid ambiguities this terminology is based on the anatomy of each animal in a standard way, for humans, one type of vertebrate, anatomical terms may differ from other forms of vertebrates. Thus what is on top of a human is the head, whereas the top of a dog may be its back, for example, many species are not even bilaterally symmetrical. In these species, terminology depends on their type of symmetry, all descriptions are with respect to the organism in its standard anatomical position, even when the organism in question has appendages in another position. This helps avoid confusion in terminology when referring to the organism in different postures. In humans, this refers to the body in a position with arms at the side. While the universal vertebrate terminology used in medicine would work in human medicine. Many anatomical terms can be combined, either to indicate a position in two axes simultaneously or to indicate the direction of a movement relative to the body, for example, anterolateral indicates a position that is both anterior and lateral to the body axis. There is no limit to the contexts in which terms may be modified to qualify each other in such combinations. Generally the modifier term is truncated and an o or an i is added in prefixing it to the qualified term, where desirable three or more terms may be agglutinated or concatenated, as in anteriodorsolateral. Such terms sometimes used to be hyphenated, but the tendency is to omit the hyphen. There is however little basis for any rule to interfere with choice of convenience in such usage
22.
Thorax (insect anatomy)
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The thorax is the midsection of the insect body. It holds the head, legs, wings and abdomen and it is also called mesosoma in other arthropods. In dragonflies and damselflies the mesothorax and metathorax are fused together to form the synthorax, in some insect pupae, like the mosquitoes, the head and thorax can be fused in a cephalothorax. Members of sub order Apocrita in the order Hymenoptera have the first segment of the abdomen fused with the thorax, which is called the propodeum
23.
Head
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A head is the part of an organism which usually includes the eyes, ears, nose and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple animals may not have a head, but many bilaterally symmetric forms do, heads develop in animals by an evolutionary trend known as cephalization. In bilaterally symmetrical animals, nervous tissues concentrate at the anterior region, through biological evolution, sense organs and feeding structures also concentrate into the anterior region, these collectively form the head. The human head is a unit that consists of the skull, hyoid bone. The term skull collectively denotes the mandible and the cranium, the skull can also be described as being composed of the cranium, which encloses the cranial cavity, and the facial skeleton. There are eight bones in the cranium and fourteen in the facial skeleton, sculptures of human heads are generally based on a skeletal structure that consists of a cranium, jawbone, and cheekbone. Proponents of identism believe that the mind is identical to the brain, philosopher John Searle asserts his identist beliefs, stating the brain is the only thing in the human head. Similarly, Dr. Henry Bennet-Clark has stated that the head encloses billions of miniagents and microagents, evolution of the head In the vertebrates has occurred by the fusion of a fixed number of anterior segments, in the same manner as in other ”heteronomously segmented animals”. In some cases segments or a portion of the segments disappear, the head segments also lose most of its systems except for the nervous system. In some arthropods, especially trilobites, the cephalon, or cephalic region, is the region of the head which is a collective of fused segments, a typical insect head is composed of eyes, antennae, and components of mouth. As these components differ substantially from insect to insect, they form important identification links, eyes in the head found, in several types of insects, are in the form of a pair of compound eyes with multiple faces. In many other types of insects the compound eyes are seen in a facet or group of single facets. In some case, the eyes may be seen as marks on the dorsal or located near or toward the head, antennae on the insects head is found in the form of segmented attachments, in pairs, that are usually located between the eyes. These are in varying shapes and sizes, in the form of filaments or in different enlarged or clubbed form, insects have mouth parts in various shapes depending on their feeding habits. Labrum is the lip which is in the front area of the head and is the most exterior part. A pair of mandible is found on backside of the labrum flanking the side of the mouth, at the back side of the mouth is the labium or lower lip. There is also a mouth part in some insects which is termed as hypopharynx which is usually located between the maxillac. The heads of humans and other animals are commonly recurring charges in heraldry, several varieties of womens heads also occur, including maidens heads, ladies heads, nuns heads, and occasionally queens heads
24.
Abdomen
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The abdomen constitutes the part of the body between the thorax and pelvis, in humans and in other vertebrates. The region occupied by the abdomen is termed the abdominal cavity, in arthropods it is the posterior tagma of the body, it follows the thorax or cephalothorax. The abdomen stretches from the thorax at the diaphragm to the pelvis at the pelvic brim. The pelvic brim stretches from the joint to the pubic symphysis and is the edge of the pelvic inlet. The space above this inlet and under the thoracic diaphragm is termed the abdominal cavity, the boundary of the abdominal cavity is the abdominal wall in the front and the peritoneal surface at the rear. The abdomen contains most of the organs of the digestive tract. Hollow abdominal organs include the stomach, the intestine. Organs such as the liver, its attached gallbladder, and the function in close association with the digestive tract. The spleen, kidneys, and adrenal glands also lie within the abdomen, along with blood vessels including the aorta. Anatomists may consider the urinary bladder, uterus, fallopian tubes, finally, the abdomen contains an extensive membrane called the peritoneum. A fold of peritoneum may completely cover certain organs, whereas it may only one side of organs that usually lie closer to the abdominal wall. Anatomists call the type of organs retroperitoneal. For example, the stomach of ruminants is divided into four chambers – rumen, in vertebrates, the abdomen is a large cavity enclosed by the abdominal muscles, ventrally and laterally, and by the vertebral column dorsally. Lower ribs can also enclose ventral and lateral walls, the abdominal cavity is upper part of the pelvic cavity. It is attached to the cavity by the diaphragm. Structures such as the aorta, inferior vena cava and esophagus pass through the diaphragm, both the abdominal and pelvic cavities are lined by a serous membrane known as the parietal peritoneum. This membrane is continuous with the visceral peritoneum lining the organs, the abdomen in vertebrates contains a number of organs belonging, for instance, to the digestive tract and urinary system. There are three layers of the abdominal wall and they are, from the outside to the inside, external oblique, internal oblique, and transverse abdominal
25.
Segmentation (biology)
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Segmentation in biology refers to the division of some animal and plant body plans into a series of repetitive segments. This article focuses on the segmentation of animal body plans, specifically using the examples of the taxa Arthropoda, Chordata and these three groups form segments by using a “growth zone” to direct and define the segments. While all three have a segmented body plan and use a “growth zone, ” they use different mechanisms for generating this patterning. Even within these groups, different organisms have different mechanisms for segmenting the body, segmentation of the body plan is important for allowing free movement and development of certain body parts. It also allows for regeneration in specific individuals, segmentation is a difficult process to satisfactorily define. Many taxa have some form of repetition in their units. Segmentation in animals typically falls into three types characteristic of different arthropods, vertebrates, and annelids, the arthropod fruit fly forms segments from a field of equivalent cells based on transcription factor gradients. The vertebrate zebrafish uses oscillating gene expression to define segments known as somites, the annelid leech uses smaller blast cells budded off from large teloblast cells to define segments. Although Drosophila segmentation is not representative of the phylum in general. The drosophila as an organism is ideal for genetic screens. Early screens to identify genes involved in development led to the discovery of a class of genes that was necessary for proper segmentation of the drosophila embryo. To properly segment the drosophila embryo, the axis is defined by maternally supplied transcripts giving rise to gradients of these proteins. This gradient then defines the pattern for gap genes, which set up the boundaries between the different segments. The gradients produced from gap gene expression then define the pattern for the pair-rule genes. The pair-rule genes are mostly transcription factors, expressed in regular stripes down the length of the embryo and these transcription factors then regulate the expression of segment polarity genes, which define the polarity of each segment. Boundaries and identities of each segment are later defined, within the arthropods, the body wall, nervous system, kidneys, muscles and body cavity are segmented, as are the appendages. Some of these elements are not segmented in their sister taxon, while not as well studied as in Drosophila and zebrafish, segmentation in the leech has been described as “budding” segmentation. Early divisions within the leech embryo result in teloblast cells, which are cells that divide asymmetrically to create bandlets of blast cells
26.
Antenna (biology)
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Antennae, sometimes referred to as feelers, are paired appendages used for sensing in arthropods. Antennae are connected to the first one or two segments of the arthropod head and they vary widely in form, but are always made of one or more jointed segments. While they are sensory organs, the exact nature of what they sense. Functions may variously include sensing touch, air motion, heat, vibration, antennae are sometimes modified for other purposes, such as mating, brooding, swimming, and even anchoring the arthropod to a substrate. Larval arthropods have antennae that differ from those of the adult, many crustaceans, for example, have free-swimming larval forms that use their antennae for swimming. Except the chelicerates and proturans, which have none, all non-crustacean arthropods have a pair of antennae. Crustaceans bear two pairs of antennae, the pair attached to the first segment of the head are called primary antennae or antennules. This pair is generally uniramous, but is biramous in crabs and lobsters, the pair attached to the second segment are called secondary antennae or simply antennae. The second antennae are biramous, but many species later evolved uniramous pairs. The second antennae may be reduced, apparently absent, or modified to such an extent that they no longer resemble antennae. The subdivisions of crustacean antennae have many names, including flagellomeres, annuli, articles, the terminal ends of crustacean antennae have two major categorizations, segmented and flagellate. An antenna is considered segmented if each of the annuli is separate from those around it and has individual muscle attachments. Flagellate antennae, on the hand, have muscle attachments only around the base. There are several notable uses of antennae in crustaceans. Many crustaceans have a larval stage called a nauplius, which is characterized by its use of antennae for swimming. Barnacles, a highly modified crustacean, use their antennae to attach to rocks, insects evolved from prehistoric crustaceans, and they have secondary antennae like crustaceans, but not primary antennae. Antennae are the primary olfactory sensors of insects and are accordingly well-equipped with a variety of sensilla. Paired, mobile, and segmented, they are located between the eyes on the forehead, embryologically, they represent the appendages of the second head segment
27.
Arthropod eye
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The arthropods ancestrally possessed compound eyes, but the type and origin of this eye varies between groups, and some taxa have secondarily developed simple eyes. Apposition eyes are the most common form of eye, and are presumably the ancestral form of compound eye and they are found in all arthropod groups, although they may have evolved more than once within this phylum. Some annelids and bivalves also have apposition eyes and they are also possessed by Limulus, the horseshoe crab, and there are suggestions that other chelicerates developed their simple eyes by reduction from a compound starting point. Some caterpillars appear to have evolved compound eyes from simple eyes in the opposite fashion, most arthropods have at least one of two types of eye, lateral compound eyes, and smaller median ocelli, which are simple eyes. When both are present, the two eye types are used in concert because each has its own advantage, flying insects can remain level with either type of eye surgically removed, but the two types combine to give better performance. Ocelli can detect light levels, and have a faster response time. Most species of Arthropoda with compound eyes bear just two eyes that are located separately and symmetrically, one on side of the head. Examples include most insects, and most of the species of Crustacea. However, there are variations on that scheme, in some groups of animals whose ancestors originally were dichoptic, the eyes of modern species may be crowded together in the median plane, examples include many of the Archaeognatha. In extreme cases such eyes may fuse, effectively into an eye, as in some of the Copepoda. One term for such an arrangement of eyes is cycloptic, on the other hand, some modes of life demand enhanced visual acuity, which in compound eyes demands a larger number of ommatidia, which in turn demands larger compound eyes. The result is that the eyes occupy most of the surface of the head, reducing the area of the frons. Though technically such eyes still may be regarded dichoptic, the result in the case is that borders of such eyes meet. Such an anatomy is called holoptic, spectacular examples may be seen in the Anisoptera and various flies, such as some Acroceridae and Tabanidae. In contrast, the need for particular functions may not require large eyes. Their eyes accordingly are placed in a position for all-round vision. Again, particularly in some Diptera, ommatidia in different regions of the male eye may differ visibly in size. The head patterning is controlled by orthodenticle, a gene which demarcates the segments from the top-middle of the head to the more lateral aspects
28.
Arthropod leg
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The arthropod leg is a form of jointed appendage of arthropods, usually used for walking. Homologies of leg segments between groups are difficult to prove and are the source of much argument, some authors posit up to eleven segments per leg for the most recent common ancestor of extant arthropods but modern arthropods have eight or fewer. It has been argued that the ancestral leg need not have been so complex, the appendages of arthropods may be either biramous or uniramous. A uniramous limb comprises a series of segments attached end-to-end. A biramous limb, however, branches into two, and each consists of a series of segments attached end-to-end. The external branch of the appendages of crustaceans is known as the exopod or exopodite, other structures aside from the latter two are termed exites and endites. Exopodites can be distinguished from exites by the possession of internal musculature. The exopodites can sometimes be missing in some groups. The legs of insects and myriapods are uniramous, in crustaceans, the first antennae are uniramous, but the second antennae are biramous, as are the legs in most species. For a time, possession of uniramous limbs was believed to be a shared, derived character and it is now believed that several groups of arthropods evolved uniramous limbs independently from ancestors with biramous limbs, so this taxon is no longer used. The situation is identical in scorpions, but with the addition of a pre-tarsus beyond the tarsus, the claws of the scorpion are not truly legs, but are pedipalps, a different kind of appendage that is also found in spiders and is specialised for predation and mating. In Limulus, there are no metatarsi or pretarsi, leaving six segments per leg, the legs of crustaceans are divided primitively into seven segments, which do not follow the naming system used in the other groups. They are, coxa, basis, ischium, merus, carpus, propodus, in some groups, some of the limb segments may be fused together. The claw of a lobster or crab is formed by the articulation of the dactylus against an outgrowth of the propodus, crustacean limbs also differ in being biramous, whereas all other extant arthropods have uniramous limbs. Myriapods have seven-segmented walking legs, comprising coxa, trochanter, prefemur, femur, tibia, tarsus, myriapod legs show a variety of modifications in different groups. In all centipedes, the first pair of legs is modified into a pair of venomous fangs called forcipules, in most millipedes, one or two pairs of walking legs in adult males are modified into sperm-transferring structures called gonopods. In some millipedes, the first leg pair in males may be reduced to tiny hooks or stubs, insects and their relatives are hexapods, having six legs, connected to the thorax, each with five components. In order from the body they are the coxa, trochanter, femur, tibia, each is a single segment, except the tarsus which can be from three to seven segments, each referred to as a tarsomere
29.
Claw
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A claw is a curved, pointed appendage, found at the end of a toe or finger in most amniotes. Some invertebrates such as beetles and spiders have somewhat similar fine hooked structures at the end of the leg or tarsus for gripping a surface as the creature walks, crabs, lobsters and scorpions pincers, or more formally, their chelae, are sometimes called claws. A true claw, is made of protein called keratin. Similar appendages that are flat and do not come to a point are called nails instead. Claw-like projections that do not form at the end of digits, in tetrapods, claws are made of keratin and consist of two layers. The unguis is the external layer, which consists of keratin fibers arranged perpendicular to the direction of growth. The subunguis is the softer, flaky underside layer whose grain is parallel to the direction of growth, the claw grows outward from the nail matrix at the base of the unguis and the subunguis grows thicker while travelling across the nail bed. The unguis grows outward faster than the subunguis to produce a curve, tetrapods use their claws in many ways, commonly to grasp or kill prey, to dig and to climb and hang. All Carnivora have claws, which vary considerably in length and shape, Claws grow out of the third phalanges of the paws and are made of keratin. Many predatory mammals have protractile claws that can hide inside the animals paw, especially the cat family, Felidae. Outside of the cat family, retractable claws are found only in species of the Viverridae. A claw that is retractable is protected from wear and tear, most cats and dogs also have a dewclaw on the inside of the front paws. It is much less functional than the other claws but does help the cats to grasp prey, because the dew claw does not touch the ground, it receives less wear and tends to be sharper and longer. A nail is homologous to a claw but is flatter and has a curved edge instead of a point, a nail that is big enough to bear weight is called a hoof. Every so often, the growth of claws stops and restarts, in hair, this results in the hair falling out and being replaced by a new one. In claws, this results in an layer, and the old segment breaks off. This process takes several months for human thumbnails, cats are often seen working old unguis layers off on wood or on boards made for the purpose. Ungulates hooves wear or self-trim by ground contact, domesticated equids usually need regular trimming by a farrier, as a consequence of reduced activity on hard ground
30.
Spiracle
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Spiracles are openings on the surface of some animals, which usually lead to respiratory systems. The spiracle is a hole behind each eye that opens to the mouth in some fish. In the primitive jawless fish the first gill opening immediately behind the mouth is essentially similar to the gill opening. The gill opening was closed off from below, the opening was small and hole-like. The spiracle is still found in all cartilaginous fish except requiem sharks, hammerhead sharks, and chimaeras, and is found in primitive bony fishes. It is also seen as a notch in the skull of the extinct labyrinthodonts. Insects and some more derived spiders have spiracles on their exoskeletons to allow air to enter the trachea, in the respiratory system of insects, the tracheal tubes primarily deliver oxygen directly into the animals tissues. The spiracles can be opened and closed in an efficient manner to reduce water loss and this is done by contracting closer muscles surrounding the spiracle. In order to open, the muscle relaxes, the closer muscle is controlled by the central nervous system but can also react to localized chemical stimuli. Several aquatic insects have similar or alternative closing methods to prevent water entering the trachea. The timing and duration of spiracle closures can affect the rates of the organism. Spiracles may also be surrounded by hairs to minimize bulk air movement around the opening, and thus minimize water loss
31.
Anus
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The anus is an opening at the opposite end of an animals digestive tract from the mouth. Amphibians, reptiles, and birds use the same orifice for excreting liquid and solid wastes, for copulation, monotreme mammals also have a cloaca, which is thought to be a feature inherited from the earliest amniotes via the therapsids. Marsupials have a single orifice for excreting both solids and liquids and, in females, a vagina for reproduction. The development of the anus was an important stage in the evolution of multicellular animals and it appears to have happened at least twice, following different paths in protostomes and deuterostomes. In animals at least as complex as an earthworm, the forms a dent on one side, the blastopore, which deepens to become the archenteron. In deuterostomes, the original dent becomes the anus while the gut tunnels through to make another opening. The protostomes were so named because it was thought that in their embryos the dent formed the mouth first and the anus was formed later at the opening made by the other end of the gut. More recent research, however, shows that in protostomes the edges of the dent close up in the middle, leaving openings at the ends become the mouth. Anal canal Imperforate anus, a birth defect, media related to Anus at Wikimedia Commons
32.
Oviparous
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Oviparous animals are animals that lay eggs, with little or no other embryonic development within the mother. This is the method of most fish, amphibians, reptiles, all birds. In traditional usage, most insects, molluscs, and arachnids are also described as oviparous, Thierry Lodé, however, however, the biologist Thierry Lodé recently divided the traditional category of oviparous reproduction into two modes that he named ovuliparity and oviparity respectively. Among the Vertebrata ovuliparity is common among fishes and most Amphibia and it occurs among Cnidaria, Ctenophora, Echinodermata, Mollusca, and several other phyla as well. Oviparity, in which fertilisation is internal, the egg is not retained in the body for most of the period of development of the embryo within the egg, which is the main distinction between oviparity and ovoviviparity. Oviparity occurs in all birds, most reptiles, some fishes, among mammals, the monotremes are oviparous. Such classifications are largely for convenience and as such can be important in practice, — but speaking loosely in contexts in which the distinction is not relevant, it is common to lump both categories together as oviparous. Oviparity at the US National Library of Medicine Medical Subject Headings
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Egg
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An egg is the organic vessel containing the zygote in which an animal embryo develops until it can survive on its own, at which point the animal hatches. An egg results from fertilization of an ovum, most arthropods, vertebrates, and mollusks lay eggs, although some do not, such as scorpions and most mammals. Reptile eggs, bird eggs, and monotreme eggs are laid out of water, eggs laid on land or in nests are usually kept within a favorable temperature range while the embryo grows. When the embryo is developed it hatches, i. e. breaks out of the eggs shell. Some embryos have an egg tooth with which to crack, pip. The largest recorded egg is from a shark, and was 30 cm ×14 cm ×9 cm in size. At 1.5 kg and up to 17.8 cm ×14 cm, the bee hummingbird produces the smallest known bird egg, which weighs half of a gram. The eggs laid by some reptiles and most fish can be smaller. Reproductive structures similar to the egg in other kingdoms are termed spores, or in spermatophytes seeds, several major groups of animals typically have readily distinguishable eggs. The most common strategy for fish is known as oviparity. Typically large numbers of eggs are laid at one time and the eggs are left to develop without parental care. When the larvae hatch from the egg, they carry the remains of the yolk in a yolk sac which continues to nourish the larvae for a few days as they learn how to swim. Once the yolk is consumed, there is a point after which they must learn how to hunt. A few fish, notably the rays and most sharks use ovoviviparity in which the eggs are fertilized, however the larvae still grow inside the egg consuming the eggs yolk and without any direct nourishment from the mother. The mother then gives birth to relatively mature young, in certain instances, the physically most developed offspring will devour its smaller siblings for further nutrition while still within the mothers body. This is known as intrauterine cannibalism, the eggs of fish and amphibians are jellylike. Cartilagenous fish eggs are fertilized internally and exhibit a variety of both internal and external embryonic development. Most fish species spawn eggs that are fertilized externally, typically with the male inseminating the eggs after the female lays them and these eggs do not have a shell and would dry out in the air
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Chitin
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Chitin n is a long-chain polymer of an N-acetylglucosamine, a derivative of glucose, and is found in many places throughout the natural world. The structure of chitin is comparable to the cellulose, forming crystalline nanofibrils or whiskers. In terms of function, it may be compared to the protein keratin, chitin has proved versatile for several medicinal, industrial and biotechnological purposes. The English word chitin comes from the French word chitine, which first appeared in 1821 and derived from the Greek word χιτών, a similar word, chiton, refers to a marine animal with a protective shell. The structure of chitin was solved by Albert Hofmann in 1929, chitin is a modified polysaccharide that contains nitrogen, it is synthesized from units of N-acetyl-D-glucosamine. Therefore, chitin may be described as cellulose with one group on each monomer replaced with an acetyl amine group. This allows for increased hydrogen bonding between adjacent polymers, giving the chitin-polymer matrix increased strength, in its pure, unmodified form, chitin is translucent, pliable, resilient, and quite tough. Combined with calcium carbonate, as in the shells of crustaceans and molluscs and this composite material is much harder and stiffer than pure chitin, and is tougher and less brittle than pure calcium carbonate. Another difference between pure and composite forms can be seen by comparing the body wall of a caterpillar to the stiff. The elaborate chitin gyroid construction in butterfly wings creates a model of optical devices having potential for innovations in biomimicry, scarab beetles in the genus Cyphochilus also utilize chitin to form extremely thin scales that diffusely reflect white light. These scales are networks of randomly ordered filaments of chitin with diameters on the scale of hundreds of nanometres, the multiple scattering of light is thought to play a role in the unusual whiteness of the scales. In addition, some wasps, such as Protopolybia chartergoides, orally secrete material containing predominantly chitin to reinforce the outer nest envelopes. Chitosan is produced commercially by deacetylation of chitin, chitosan is soluble in water, chitin producing organisms like protozoa, fungi, arthropods, and nematodes are often pathogens in other species. Keratinocytes in skin can also react to chitin or chitin fragments, according to in vitro studies, chitin is sensed by receptors, such as FIBCD1, KLRB1, REG3G, Toll-like receptor 2, CLEC7A, and mannose receptors. Plants also have receptors that can cause a response to chitin, namely chitin elicitor receptor kinase 1, the first chitin receptor was cloned in 2006. When the receptors are activated by chitin, genes related to plant defense are expressed, and jasmonate hormones are activated, commensal fungi that have ways to interact with the host immune response that as of 2016 were not well understood. Some pathogens produce chitin-binding proteins that mask the chitin they shed from these receptors, zymoseptoria tritici is an example of a fungal pathogen that has such blocking proteins, it is a major pest in wheat crops. Chitin was probably present in the exoskeletons of Cambrian arthropods such as trilobites, the oldest preserved chitin dates to the Oligocene, about 25 million years ago, consisting of a scorpion encased in amber
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Protein
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Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, a linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide, short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides, or sometimes oligopeptides. The individual amino acid residues are bonded together by peptide bonds, the sequence of amino acid residues in a protein is defined by the sequence of a gene, which is encoded in the genetic code. In general, the code specifies 20 standard amino acids, however. Sometimes proteins have non-peptide groups attached, which can be called prosthetic groups or cofactors, proteins can also work together to achieve a particular function, and they often associate to form stable protein complexes. Once formed, proteins only exist for a period of time and are then degraded and recycled by the cells machinery through the process of protein turnover. A proteins lifespan is measured in terms of its half-life and covers a wide range and they can exist for minutes or years with an average lifespan of 1–2 days in mammalian cells. Abnormal and or misfolded proteins are degraded more rapidly due to being targeted for destruction or due to being unstable. Like other biological macromolecules such as polysaccharides and nucleic acids, proteins are essential parts of organisms, many proteins are enzymes that catalyse biochemical reactions and are vital to metabolism. Proteins also have structural or mechanical functions, such as actin and myosin in muscle and the proteins in the cytoskeleton, other proteins are important in cell signaling, immune responses, cell adhesion, and the cell cycle. In animals, proteins are needed in the diet to provide the essential amino acids that cannot be synthesized, digestion breaks the proteins down for use in the metabolism. Methods commonly used to study structure and function include immunohistochemistry, site-directed mutagenesis, X-ray crystallography, nuclear magnetic resonance. Most proteins consist of linear polymers built from series of up to 20 different L-α-amino acids, all proteinogenic amino acids possess common structural features, including an α-carbon to which an amino group, a carboxyl group, and a variable side chain are bonded. Only proline differs from this structure as it contains an unusual ring to the N-end amine group. The amino acids in a chain are linked by peptide bonds. Once linked in the chain, an individual amino acid is called a residue, and the linked series of carbon, nitrogen. The peptide bond has two forms that contribute some double-bond character and inhibit rotation around its axis, so that the alpha carbons are roughly coplanar
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Keratin
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Keratin is one of a family of fibrous structural proteins. Keratin is the protein that protects cells from damage or stress. It is the key structural material making up the layer of human skin. Keratin monomers assemble into bundles to form filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians. The only other biological matter known to approximate the toughness of keratinized tissue is chitin, keratin derives from Greek κερατίνη from Greek keras meaning horn originating from the Proto-Indo-European *ḱer- of the same meaning. It is composed of horn like, i. e. kerato, to which the chemical suffix -in is appended, the Greek keras is used in many animal names, e. g. Rhinoceros, meaning nose with a horn. Keratin filaments are abundant in keratinocytes in the layer of the epidermis. In addition, keratin filaments are present in cells in general. For example, mouse thymic epithelial cells are known to react with antibodies for keratin 5, keratin 8 and these antibodies are used as fluorescent markers to distinguish subsets of TECs in genetic studies of the thymus. The α-keratins in the hair, stratum corneum, horns, nails, claws and hooves of mammals, the harder β-keratins found in nails and in the scales and claws of reptiles, their shells, and in the feathers, beaks, claws of birds and quills of porcupines. The baleen plates of filter-feeding whales are made of keratin, keratins are polymers of type I and type II intermediate filaments, which have only been found in the genomes of chordates. Nematodes and many other animals seem to only have type VI intermediate filaments, lamins. The human genome encodes 54 functional keratin genes which are located in two clusters on chromosomes 12 and 17 and this suggests that they have originated from a series of gene duplications on these chromosomes. The first sequences of keratins were determined by Hanukoglu and Fuchs and these sequences revealed that there are two distinct but homologous keratin families which were named as Type I keratin and Type II keratins. This model has been confirmed by the determination of the structure of a helical domain of keratins. Fibrous keratin molecules supercoil to form a stable, left-handed superhelical motif to multimerise. The major force that keeps the structure is hydrophobic interactions between apolar residues along the keratins helical segments. Limited interior space is the reason why the triple helix of the protein collagen, found in skin, cartilage and bone
37.
Oviposition
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Oviparous animals are animals that lay eggs, with little or no other embryonic development within the mother. This is the method of most fish, amphibians, reptiles, all birds. In traditional usage, most insects, molluscs, and arachnids are also described as oviparous, Thierry Lodé, however, however, the biologist Thierry Lodé recently divided the traditional category of oviparous reproduction into two modes that he named ovuliparity and oviparity respectively. Among the Vertebrata ovuliparity is common among fishes and most Amphibia and it occurs among Cnidaria, Ctenophora, Echinodermata, Mollusca, and several other phyla as well. Oviparity, in which fertilisation is internal, the egg is not retained in the body for most of the period of development of the embryo within the egg, which is the main distinction between oviparity and ovoviviparity. Oviparity occurs in all birds, most reptiles, some fishes, among mammals, the monotremes are oviparous. Such classifications are largely for convenience and as such can be important in practice, — but speaking loosely in contexts in which the distinction is not relevant, it is common to lump both categories together as oviparous. Oviparity at the US National Library of Medicine Medical Subject Headings
38.
Nymph (biology)
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In biology, a nymph is the immature form of some invertebrates, particularly insects, which undergoes gradual metamorphosis before reaching its adult stage. Unlike a typical larva, an overall form already resembles that of the adult. In addition, while a nymph moults it never enters a pupal stage, instead, the final moult results in an adult insect. Nymphs undergo multiple stages of development called instars and this is the case, for example, in Orthoptera, Hemiptera, mayflies, termites, cockroaches, mantises, stoneflies and Odonata. Nymphs of aquatic insects, as in the Odonata, Ephemeroptera, and Plecoptera, are called naiads. In older literature, these were referred to as the heterometabolous insects, as their adult. In fly fishing with flies, this stage of aquatic insects is the basis for an entire series of representative patterns for trout. They account for half of the over all patterns regularly fished in the United States
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Embryo
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An embryo is an early stage of development of a multicellular diploid eukaryotic organism. In general, in organisms that reproduce sexually, an embryo develops from a zygote, the zygote possesses half the DNA of each of its two parents. In plants, animals, and some protists, the zygote will begin to divide by mitosis to produce a multicellular organism, the result of this process is an embryo. First attested in English in the mid-14c, the word embryon derives from Medieval Latin embryo, itself from Greek ἔμβρυον, lit. Young one, which is the neuter of ἔμβρυος, lit, growing in, from ἐν, in and βρύω, swell, be full, the proper Latinized form of the Greek term would be embryum. In animals, the development of the zygote into an embryo proceeds through specific stages of blastula, gastrula. The blastula stage typically features a fluid-filled cavity, the blastocoel, surrounded by a sphere or sheet of cells, in a placental mammal, an ovum is fertilized in a fallopian tube through which it travels into the uterus. An embryo is called a fetus at an advanced stage of development. In humans, this is from the week of gestation. During gastrulation the cells of the blastula undergo coordinated processes of cell division, invasion, in triploblastic organisms, the three germ layers are called endoderm, ectoderm, and mesoderm. The position and arrangement of the layers are highly species-specific, however. For example, in neurogenesis, a subpopulation of cells is set aside to become the brain, spinal cord. Modern developmental biology is extensively probing the molecular basis for every type of organogenesis, including angiogenesis, chondrogenesis, myogenesis, osteogenesis, and many others. In botany, a plant embryo is part of a seed, consisting of precursor tissues for the leaves, stem. Once the embryo begins to germinate — grow out from the seed — it is called a seedling, bryophytes and ferns also produce an embryo, but do not produce seeds. In these plants, the embryo begins its existence attached to the inside of the archegonium on a parental gametophyte from which the egg cell was generated, the structure and development of the rest of the embryo varies by group of plants. Once the embryo has expanded beyond the enclosing archegonium, it is no longer termed an embryo, embryos are used in various fields of research and in techniques of assisted reproductive technology. An egg may be fertilized in vitro and the embryo may be frozen for later use
40.
Treatment of human head lice
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The treatment of human head lice infestation is a process for removing head lice parasites from human hair and it has been debated and studied for centuries. However, the number of cases of human louse infestations has increased worldwide since the mid-1960s, there is no product or method which assures 100% destruction of the eggs and hatched lice after a single treatment. However, there are a number of treatment modalities that can be employed with varying degrees of success and these methods include chemical treatments, natural products, combs, shaving, hot air, and silicone-based lotions. The American Academy of Pediatrics states treatment for head lice should never be initiated unless there is a diagnosis for head lice since all treatments have potential side effects. Lice eggs hatch 6–9 days after oviposition, therefore, a common recommendation is to repeat treatment with a pediculicide at least once after 10 days, when all lice have hatched. Between the two treatments the person still be infested with lice that hatch from eggs not killed by the anti-louse product. Between the treatments, it is advised to wet the hair, if no living lice are found, the treatment was successful, even if nits/eggs are visible on the hair. If living lice are still present, repeat the treatment using a product with a different active ingredient. Prophylactic treatment with pediculicides is not recommended, itching may persist for up to a week after head lice eradication. Devices blowing heated air onto the scalp have been tested for efficacy in killing lice and eggs and shows up to 99% mortality of eggs, the louse loses body moisture to the heated air and within the treatment period becomes desiccated and dies. Currently, there is only one FDA approved medical device that offers this technology, a standard home blow dryer will kill 96. 7% of eggs with proper technique. To be effective, the blow dryer must be used repeatedly until the life cycle of the lice is over. A special fine tooth comb that can pick out lice is used, for a treatment with louse comb alone, it is recommended to comb the hair for an hour to an hour and a half daily or every second day for 14 days. Wetting the hair especially with water and shampoo or conditioner will facilitate the combing, electronic lice combs use a small electrical charge to kill lice. The metal teeth of the comb have alternating positive and negative charged tines, when the comb is used on dry hair, lice make contact with multiple tines of the fine-toothed comb, thereby closing the circuit and receiving an electrical charge. A non-peer-reviewed letter has been published in a dermatology journal claiming effectiveness based on personal experience, for those with long or fine hair, the metal long tooth combs seem to snag and pull hair. Metal combs may be better for thick hair, while plastic short-tooth combs are best used for treating long, today, insecticides used for the treatment of head lice include organochlorines, organophosphates, carbamates, pyrethrins, pyrethroids, and spinosad. Other home remedies such as putting vinegar, isopropyl alcohol, olive oil, mayonnaise, or melted butter in the hair have been partially disproven, The use of plastic bags may be dangerous
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Hemimetabolism
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These groups go through gradual changes, there is no pupal stage. The nymph often somewhat resembles the adult stage but lacks wings, the Orders that contain hemimetabolous insects are, Hemiptera Orthoptera Mantodea Some Blattodea Dermaptera Odonata. Phasmatodea Phthiraptera Ephemeroptera Plecoptera Isoptera Grylloblattodea Thysanoptera In aquatic entomology, different terminology is used when categorizing insects with incomplete metamorphosis, paurometabolism refers to insects whose nymphs occupy the same environment as the adults, as in the family Gerridae of Hemiptera. The hemimetabolous insects are those whose nymphs, called naiads, occupy aquatic habitats while the adults are terrestrial and this includes all members of the orders Plecoptera, Ephemeroptera, and Odonata. Aquatic entomologists use this categorization because it specifies whether the adult will occupy an aquatic or semi aquatic habitat and this classification system is similar to previously used nomenclature in terrestrial entomology
42.
Moulting
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Moulting can involve shedding the epidermis, pelage, or other external layer. In some groups, other parts may be shed, for example. In birds, moulting is the replacement of feathers by shedding old feathers while producing new ones. Feathers are dead structures at maturity which are gradually abraded and need to be replaced, adult birds moult at least once a year, although many moult twice and a few three times each year. It is generally a slow process as birds rarely shed all their feathers at any one time, the number and area of feathers that are shed varies. In some moulting periods, a bird may renew only the feathers on the head and body, shedding the wing, some species of bird become flightless during an annual wing moult and must seek a protected habitat with a reliable food supply during that time. The process of moulting in birds is as follows, First, as the pin feathers become full feathers, other feathers are shed. This is a process that occurs in many phases. It is usually symmetrical, with feather loss equal on each side of the body, because feathers make up 4–12% of a birds body weight, it takes a large amount of energy to replace them. For this reason, moults often occur immediately after the breeding season, the plumage produced during this time is called postnuptial plumage. Prenuptial moulting occurs in red-collared widowbirds where the males replace their nonbreeding plumage with breeding plumage and it is thought that large birds can advance the moult of severely damaged feathers. In some countries, flocks of commercial layer hens are force-moulted to reinvigorate egg-laying and this causes a body weight loss of 25 to 35%, which stimulates the hen to lose her feathers, but also reinvigorates egg-production. Some flocks may be force-moulted several times, in 2003, more than 75% of all flocks were force-moulted in the US. Other methods of inducing a moult include low-density diets or dietary manipulation to create an imbalance of a particular nutrient, the most important among these include manipulation of minerals including sodium, calcium, iodine and zinc, with full or partially reduced dietary intakes. The most familiar example of moulting in reptiles is when snakes shed their skin and this is usually achieved by the snake rubbing its head against a hard object, such as a rock or piece of wood, causing the already stretched skin to split. This is similar to how one might remove a sock from ones foot by grabbing the open end, the snakes skin is often left in one piece after the moulting process, including the discarded brille, so that the moult is vital for maintaining the animals quality of vision. The skins of lizards, in contrast, generally fall off in pieces, in arthropods, such as insects, arachnids and crustaceans, moulting is the shedding of the exoskeleton, typically to let the organism grow. The new exoskeleton is soft but hardens after the moulting of the old exoskeleton
. PMID 20566863.
