The supraesophageal ganglion is the first part of the arthropod and especially insect central nervous system. It receives and processes information from the first, directly associated with the eyes is the optic lobe, as the visual center of the brain. The deutocerebrum processes sensory information from the antennae, the dorsal lobe contains motor neurons which controls the antennal muscles. Chelicerata with their antennae have a very reduced deutocerebrum. The tritocerebrum integrates sensory inputs from the two pairs of ganglia. The lobes of the split to circumvent the esophagus and begin the subesophageal ganglion. The subesophageal ganglion continues the system and lies ventral to the esophagus. Finally, the ganglia of the ventral nerve cord are found in each body segment as a fused ganglion. Erber, J. Menzel, R. Visual interneurons in the median protocerebrum of the bee, Allan M. Jing W. Wang, and Richard Axel. Spatial Representation of the Glomerular Map in the Drosophila Protocerebrum, cS1 maint, Multiple names, authors list Malun, D.
Waldow, U. Kraus, D. Boeckh, J. Connections between the deutocerebrum and the protocerebrum, and neuroanatomy of several classes of deutocerebral projection neurons in the brain of male Periplaneta americana, Uwe, Thomas A. Christensen, and J. G. Hildebrand. Structure and function of the deutocerebrum in insects, cS1 maint, Multiple names, authors list Morphology and response characteristics of neurones in the deutocerebrum of the brain in the honeybeeApis mellifera. Journal of Comparative Physiology A.164, 483–494, Morphology of the deutocerebrum of female Aedes aegypti. Technau, Gerhard M. Brain Development in Drosophila melanogaster, origin and mapping of tritocerebral neurons of locust. CS1 maint, Multiple names, authors list Chaudonneret, J. Evolution of the brain with special reference to the so-called tritocerebrum
Crustaceans form a large, diverse arthropod taxon which includes such familiar animals as crabs, crayfish, krill and barnacles. In other words, some crustaceans are more related to insects. The 67,000 described species range in size from Stygotantulus stocki at 0.1 mm, to the Japanese spider crab with a leg span of up to 3.8 m, like other arthropods, crustaceans have an exoskeleton, which they moult to grow. Most crustaceans are free-living aquatic animals, but some are terrestrial, some are parasitic, the group has an extensive fossil record, reaching back to the Cambrian, and includes living fossils such as Triops cancriformis, which has existed apparently unchanged since the Triassic period. More than 10 million tons of crustaceans are produced by fishery or farming for human consumption and copepods are not as widely fished, but may be the animals with the greatest biomass on the planet, and form a vital part of the food chain. The scientific study of crustaceans is known as carcinology, and a scientist who works in carcinology is a carcinologist, the body of a crustacean is composed of segments, which are grouped into three regions, the cephalon or head, the thorax, and the pleon or abdomen.
The head and thorax may be fused together to form a cephalothorax, the crustacean body is protected by the hard exoskeleton, which must be moulted for the animal to grow. The shell around each somite can be divided into a dorsal tergum, ventral sternum, various parts of the exoskeleton may be fused together. The abdomen bears pleopods, and ends in a telson, which bears the anus, the number and variety of appendages in different crustaceans may be partly responsible for the groups success. It is unclear whether the condition is a derived state which evolved in crustaceans. Trilobites, for instance, possessed biramous appendages, the main body cavity is an open circulatory system, where blood is pumped into the haemocoel by a heart located near the dorsum. Malacostraca have haemocyanin as the pigment, while copepods, barnacles. The alimentary canal consists of a tube that often has a gizzard-like gastric mill for grinding food and a pair of digestive glands that absorb food. Structures that function as kidneys are located near the antennae, a brain exists in the form of ganglia close to the antennae, and a collection of major ganglia is found below the gut.
In many decapods, the first pair of pleopods are specialised in the male for sperm transfer, many terrestrial crustaceans mate seasonally and return to the sea to release the eggs. Others, such as woodlice, lay their eggs on land, in most decapods, the females retain the eggs until they hatch into free-swimming larvae. Marine crustaceans are as ubiquitous in the oceans as insects are on land, some branchiurans are able to withstand rapid changes of salinity and will switch hosts from marine to non-marine species. Krill are the layer and the most important part of the food chain in Antarctic animal communities
An instar is a developmental stage of arthropods, such as insects, between each moult, until sexual maturity is reached. Arthropods must shed the exoskeleton in order to grow or assume a new form, differences between instars can often be seen in altered body proportions, patterns, changes in the number of body segments or head width. After moulting, i. e. shedding their exoskeleton, the juvenile arthropods continue in their life cycle until they pupate or moult again. This period of growth, instar, is fixed, some arthropods can continue to moult after sexual maturity, but the stages between these subsequent moults are generally not called instars. The number of instars an insect undergoes depends on the species, lower temperatures and humidity often slow the rate of development. The dictionary definition of instar at Wiktionary
A dragonfly is an insect belonging to the order Odonata, infraorder Anisoptera. Adult dragonflies are characterized by large multifaceted eyes, two pairs of transparent wings, sometimes with coloured patches and an elongated body. Dragonflies are agile fliers, while damselflies have a weaker, fluttery flight, many dragonflies have brilliant iridescent or metallic colours produced by structural coloration, making them conspicuous in flight. An adult dragonfly’s compound eye has nearly 24,000 ommatidia, fossils of very large dragonfly ancestors in the Protodonata are found from 325 million years ago in Upper Carboniferous rocks, these had wingspans up to about 750 mm. About 3000 species of Anisoptera are in the world today, most are tropical, with fewer species in temperate regions. Dragonflies are predators, both in their larval stage, when they are known as nymphs or naiads. Several years of their lives are spent as nymphs living in fresh water and they are fast, agile fliers, sometimes migrating across oceans, and are often found near water.
They have a uniquely complex mode of reproduction involving indirect insemination, delayed fertilization, loss of wetland habitat threatens dragonfly populations around the world. Dragonflies are represented in human culture on artifacts such as pottery, rock paintings and they are used in traditional medicine in Japan and China, and caught for food in Indonesia. They are symbols of courage and happiness in Japan and their bright colours and agile flight are admired in the poetry of Alfred, Lord Tennyson and the prose of H. E. Bates. Dragonflies and their relatives are an ancient group, the forerunners of modern Odonata are included in a clade called the Panodonata, which include the basal Zygoptera and the Anisoptera Today there are some 3000 species extant around the world. On the cladogram, dashed lines indicate unresolved relationships, English names are given, About 3012 species of dragonflies were known in 2010, the distribution of diversity within the biogeographical regions are summarised below.
Dragonflies are found on every continent except Antarctica, in contrast to the damselflies, which tend to have restricted distributions, some genera and species are found across continents. The globe skimmer Pantala flavescens is probably the most widespread species in the world, it is cosmopolitan. Most Anisoptera species are tropical, with far fewer species in temperate regions, Dragonflies can be found from sea level up to the mountains, decreasing in species diversity with altitude. Their altitudinal limit is about 3700 m, represented by a species of Aeshna in the Pamirs, Dragonflies become scarce at higher latitudes. They are not native to Iceland, but individuals are occasionally swept in by strong winds, including a Hemianax ephippiger native to North Africa, the treeline emerald is found in northern Alaska, within the Arctic Circle, making it the most northerly of all dragonflies. Dragonflies are heavy-bodied, strong-flying insects that hold their wings horizontally both in flight and at rest
Cnidaria is a phylum containing over 9,000 species of animals found exclusively in aquatic environments, they are predominantly marine species. Their distinguishing feature is cnidocytes, specialized cells that use mainly for capturing prey. Their bodies consist of mesoglea, a non-living jelly-like substance, sandwiched between two layers of epithelium that are one cell thick. They have two basic forms, swimming medusae and sessile polyps, both of which are radially symmetrical with mouths surrounded by tentacles that bear cnidocytes. Both forms have a single orifice and body cavity that are used for digestion and respiration, many cnidarian species produce colonies that are single organisms composed of medusa-like or polyp-like zooids, or both. Cnidarians activities are coordinated by a nerve net and simple receptors. Several free-swimming species of Cubozoa and Scyphozoa possess balance-sensing statocysts, not all cnidarians reproduce sexually, with many species having complex life cycles of asexual polyp stages and sexual medusae.
Some, omit either the polyp or the medusa stage, Cnidarians were formerly grouped with ctenophores in the phylum Coelenterata, but increasing awareness of their differences caused them to be placed in separate phyla. Staurozoa have recently been recognised as a class in their own rather than a sub-group of Scyphozoa. Most cnidarians prey on organisms ranging in size from plankton to animals several times larger than themselves, but many obtain much of their nutrition from dinoflagellates, many are preyed on by other animals including starfish, sea slugs and turtles. Many scleractinian corals—which form the foundation for coral reefs—possess polyps that are filled with zooxanthellae. While reef-forming corals are almost entirely restricted to warm and shallow waters, other cnidarians can be found at great depths, in polar regions. Recent phylogenetic analyses support monophyly of cnidarians, as well as the position of cnidarians as the group of bilaterians. Cnidarians form a phylum that are more complex than sponges, about as complex as ctenophores, and less complex than bilaterians.
Cnidarians are distinguished from all other animals by having cnidocytes that fire like harpoons and are used mainly to capture prey, in some species, cnidocytes can be used as anchors. Hence and ctenophores have traditionally been labelled diploblastic, along with sponges, both cnidarians and ctenophores have a type of muscle that, in more complex animals, arises from the middle cell layer. As a result, some recent text books classify ctenophores as triploblastic, adult cnidarians appear as either swimming medusae or sessile polyps, and many hydrozoan species are known to alternate between the two forms. Both are radially symmetrical, like a wheel and a tube respectively, since these animals have no heads, their ends are described as oral and aboral
Holometabolism, called complete metamorphism, is a form of insect development which includes four life stages – as an embryo or egg, a larva, a pupa and an imago or adult. Holometabolism is a trait of all insects in the superorder Endopterygota. In some species the life cycle prevents larvae from competing with adults because they inhabit different ecological niches. In some insects, the adults can protect and feed the younger stages, there are four general developmental stages, each with its own morphology. The first stage is from the fertilization of the egg inside the mother until the embryo hatches, the insect starts as a single cell and develops into the larval form before it hatches. The second stage lasts from hatching or birth until the larva pupates, in most species this mobile stage is worm-like in form. Such larvae can be one of several varieties, eruciform, scarabaeiform. Other species however may be campodeiform and this stage is variously adapted to gaining and accumulating the materials and energy necessary for growth and metamorphosis.
The third stage is from pupation until eclosion, the pupae of most species hardly move at all, although the pupae of some species, such as mosquitoes, are mobile. In preparation for pupation, the larvae of many species construct a cocoon of silk or other material. There are three types of pupae, obtect and coarctate, obtect pupae are compact, with the legs and other appendages enclosed. Exarate pupae have their legs and other free and extended. Coarctate pupae develop inside the larval skin, in this stage, the insects physiology and functional structure, both internal and external, change drastically. Adult holometabolous insects usually have wings and functioning reproductive organs, in this stage, reproduction is the top priority for queens and males. Around 45% to 60% of all living species are holometabolan insects. Juveniles and adult forms of insects often occupy different ecological niches. This fact is considered a key driver in the unusual evolutionary diversification of form, according to the latest phylogenetic reconstructions, holometabolan insects are monophyletic, which suggests that the evolutionary innovation of complete metamorphosis occurred only once.
Paleontological evidence shows that the first winged insects appeared in the Paleozoic, carboniferous fossil samples already display a remarkable diversity of species with functional wings
Johann Wolfgang von Goethe
Johann Wolfgang von Goethe was a German writer and statesman. In addition, numerous literary and scientific fragments, more than 10,000 letters and he was an early participant in the Sturm und Drang literary movement. He contributed to the planning of Weimars botanical park and the rebuilding of its Ducal Palace and his first major scientific work, the Metamorphosis of Plants, was published after he returned from a 1788 tour of Italy. During this period, Goethe published his novel, Wilhelm Meisters Apprenticeship, the verse epic Hermann and Dorothea, and, in 1808. Goethes comments and observations form the basis of several biographical works, Goethes father, Johann Caspar Goethe, lived with his family in a large house in Frankfurt, an Imperial Free City of the Holy Roman Empire. Though he had studied law in Leipzig and had been appointed Imperial Councillor, Johann Caspar married Goethes mother, Catharina Elizabeth Textor at Frankfurt on 20 August 1748, when he was 38 and she was 17. All their children, with the exception of Johann Wolfgang and his sister, Cornelia Friederica Christiana and his father and private tutors gave Goethe lessons in all the common subjects of their time, especially languages.
Goethe received lessons in dancing and fencing, Johann Caspar, feeling frustrated in his own ambitions, was determined that his children should have all those advantages that he had not. Although Goethes great passion was drawing, he became interested in literature, Friedrich Gottlieb Klopstock. He took pleasure in reading works on history and religion. He writes about this period, Goethe became acquainted with Frankfurt actors, among early literary attempts, he was infatuated with Gretchen, who would reappear in his Faust and the adventures with whom he would concisely describe in Dichtung und Wahrheit. He adored Caritas Meixner, a wealthy Worms traders daughter and friend of his sister, Goethe studied law at Leipzig University from 1765 to 1768. He detested learning age-old judicial rules by heart, preferring instead to attend the lessons of Christian Fürchtegott Gellert. In Leipzig, Goethe fell in love with Anna Katharina Schönkopf, in 1770, he anonymously released Annette, his first collection of poems.
His uncritical admiration for many contemporary poets vanished as he became interested in Gotthold Ephraim Lessing, already at this time, Goethe wrote a good deal, but he threw away nearly all of these works, except for the comedy Die Mitschuldigen. The restaurant Auerbachs Keller and its legend of Fausts 1525 barrel ride impressed him so much that Auerbachs Keller became the real place in his closet drama Faust Part One. As his studies did not progress, Goethe was forced to return to Frankfurt at the close of August 1768, Goethe became severely ill in Frankfurt. During the year and a half that followed, because of several relapses, during convalescence, Goethe was nursed by his mother and sister
Birth, known as parturition, is the act or process of bearing or bringing forth offspring. In some species the offspring is precocial and can move around almost immediately after birth but in others it is altricial, in marsupials, the fetus is born at a very immature stage after a short gestational period and develops further in its mothers wombs pouch. It is not only humans and mammals give birth. Some reptiles, amphibians and invertebrates carry their young inside them. Some of these are ovoviviparous, with the eggs being hatched inside the mothers body, in these large animals, the birth process is similar to that of a human, though in most the offspring is precocial. This means that it is born in an advanced state than a human baby and is able to stand, walk. In the case of whales and porpoises, the calf is normally born tail first which minimises the risk of drowning. The mother encourages the newborn calf to rise to the surface of the water to breathe, most smaller mammals have multiple births, producing litters of young which may number twelve or more.
In these animals, each fetus is surrounded by its own amniotic sac and has a separate placenta and this separates from the wall of the uterus during labor and the fetus works its way towards the birth canal. Humans usually produce a single offspring at a time, the mothers body is prepared for birth by hormones produced by the pituitary gland, the ovary and the placenta. The total gestation period from fertilization to birth is normally about 38 weeks, the normal process of childbirth takes several hours and has three stages. The first stage starts with a series of contractions of the muscular walls of the uterus. The active phase of the first stage starts when the cervix is dilated more than about 4 cm in diameter and is when the contractions become stronger, the head of the baby is pushed against the cervix, which gradually dilates until is fully dilated at 10 cm diameter. At some time, the sac bursts and the amniotic fluid escapes. In stage three, which begins after the birth of the baby, further contractions expel the placenta, amniotic sac, enormous changes take place in the newborns circulation to enable breathing in air.
The umbilical vein, umbilical arteries, ductus venosus and ductus arteriosus are not needed for life in air, birthing in cattle is typical of a larger mammal. A cow goes through three stages of labor during normal delivery of a calf, during stage one, the animal seeks a quiet place away from the rest of the herd. Hormone changes cause soft tissues of the canal to relax as the mothers body prepares for birth
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology encompasses the biology of regeneration, asexual reproduction and metamorphosis and in the growth, regional specification refers to the processes that create spatial pattern in a ball or sheet of initially similar cells. This generally involves the action of cytoplasmic determinants, located within parts of the fertilized egg, the early stages of regional specification do not generate functional differentiated cells, but cell populations committed to develop to a specific region or part of the organism. These are defined by the expression of combinations of transcription factors. Morphogenesis relates to the formation of three-dimensional shape and it mainly involves the orchestrated movements of cell sheets and of individual cells. Morphogenesis is important for creating the three layers of the early embryo and for building up complex structures during organ development. Cell differentiation relates specifically to the formation of cell types such as nerve, muscle.
Differentiated cells contain large amounts of proteins associated with the cell function. Growth involves both an increase in size, and the differential growth of parts which contributes to morphogenesis. Growth mostly occurs through cell division but changes of cell size. The control of timing of events and the integration of the processes with one another is the least well understood area of the subject. It remains unclear whether animal embryos contain a master clock mechanism or not, the development of plants involves similar processes to that of animals. However plant cells are mostly immotile so morphogenesis is achieved by differential growth, the inductive signals and the genes involved in plant development are different from those that control animal development. Cell differentiation is the process whereby different functional cell types arise in development, for example, muscle fibers and hepatocytes are well known types of differentiated cell. The genes encoding these proteins are highly active, for example, NeuroD is a key transcription factor for neuronal differentiation, myogenin for muscle differentiation, and HNF4 for hepatocyte differentiation.
Cell differentiation is usually the final stage of development, preceded by several states of commitment which are not visibly differentiated, a single tissue, formed from a single type of progenitor cell or stem cell, often consists of several differentiated cell types. Control of their formation involves a process of inhibition, based on the properties of the Notch signaling pathway. For example, in the plate of the embryo this system operates to generate a population of neuronal precursor cells in which NeuroD is highly expressed
A fish is any member of a group of animals that consist of all gill-bearing aquatic craniate animals that lack limbs with digits. They form a group to the tunicates, together forming the olfactores. Included in this definition are the living hagfish and cartilaginous, tetrapods emerged within lobe-finned fishes, so cladistically they are fish as well. However, traditionally fish are rendered obsolete or paraphyletic by excluding the tetrapods, because in this manner the term fish is defined negatively as a paraphyletic group, it is not considered a formal taxonomic grouping in systematic biology. The traditional term pisces is considered a typological, but not a phylogenetic classification, the earliest organisms that can be classified as fish were soft-bodied chordates that first appeared during the Cambrian period. Although they lacked a true spine, they possessed notochords which allowed them to be more agile than their invertebrate counterparts, fish would continue to evolve through the Paleozoic era, diversifying into a wide variety of forms.
Many fish of the Paleozoic developed external armor that protected them from predators, the first fish with jaws appeared in the Silurian period, after which many became formidable marine predators rather than just the prey of arthropods. Fish are abundant in most bodies of water and they can be found in nearly all aquatic environments, from high mountain streams to the abyssal and even hadal depths of the deepest oceans. With 33,100 described species, fish exhibit greater species diversity than any group of vertebrates. Fish are an important resource for humans worldwide, especially as food and subsistence fishers hunt fish in wild fisheries or farm them in ponds or in cages in the ocean. They are caught by fishers, kept as pets, raised by fishkeepers. Fish have had a role in culture through the ages, serving as deities, religious symbols, fish do not represent a monophyletic group, and therefore the evolution of fish is not studied as a single event. Early fish from the record are represented by a group of small, jawless.
Jawless fish lineages are mostly extinct, an extant clade, the lampreys may approximate ancient pre-jawed fish. The first jaws are found in Placodermi fossils, the diversity of jawed vertebrates may indicate the evolutionary advantage of a jawed mouth. It is unclear if the advantage of a hinged jaw is greater biting force, improved respiration, fish may have evolved from a creature similar to a coral-like sea squirt, whose larvae resemble primitive fish in important ways. The first ancestors of fish may have kept the form into adulthood. Fish are a group, that is, any clade containing all fish contains the tetrapods
The molluscs compose the large phylum Mollusca of invertebrate animals. Around 85,000 extant species of molluscs are recognized, molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs live in freshwater and terrestrial habitats and they are highly diverse, not just in size and in anatomical structure, but in behaviour and in habitat. The phylum is divided into 9 or 10 taxonomic classes. The gastropods are by far the most numerous molluscs in terms of classified species, the three most universal features defining modern molluscs are a mantle with a significant cavity used for breathing and excretion, the presence of a radula, and the structure of the nervous system. Other than these things, molluscs express great morphological diversity, so many textbooks base their descriptions on an ancestral mollusc. This has a single, limpet-like shell on top, which is made of proteins and chitin reinforced with calcium carbonate, the underside of the animal consists of a single muscular foot.
Although molluscs are coelomates, the coelom tends to be small, the main body cavity is a hemocoel through which blood circulates, their circulatory systems are mainly open. The generalized mollusc has two paired nerve cords, or three in bivalves, the brain, in species that have one, encircles the esophagus. Most molluscs have eyes, and all have sensors to detect chemicals, the simplest type of molluscan reproductive system relies on external fertilization, but more complex variations occur. All produce eggs, from which may emerge trochophore larvae, more complex veliger larvae, good evidence exists for the appearance of gastropods and bivalves in the Cambrian period 541 to 485.4 million years ago. Molluscs have, for centuries, been the source of important luxury goods, notably pearls, mother of pearl, Tyrian purple dye and their shells have been used as money in some preindustrial societies. Mollusc species can represent hazards or pests for human activities, the bite of the blue-ringed octopus is often fatal, and that of Octopus apollyon causes inflammation that can last for over a month.
Stings from a few species of large tropical cone shells can kill, schistosomiasis is transmitted to humans via water snail hosts, and affects about 200 million people. Snails and slugs can be serious pests, and accidental or deliberate introduction of some snail species into new environments has seriously damaged some ecosystems. The words mollusc and mollusk are both derived from the French mollusque, which originated from the Latin molluscus, from mollis, molluscus was itself an adaptation of Aristotles τα μαλακά, the soft things, which he applied to cuttlefish. The scientific study of molluscs is accordingly called malacology, as it is now known these groups have no relation to molluscs, and very little to one another, the name Molluscoida has been abandoned. The most universal features of the structure of molluscs are a mantle with a significant cavity used for breathing and excretion
Mammals are any vertebrates within the class Mammalia, a clade of endothermic amniotes distinguished from reptiles by the possession of a neocortex, three middle ear bones and mammary glands. All female mammals nurse their young with milk, secreted from the mammary glands, Mammals include the largest animals on the planet, the great whales. The basic body type is a quadruped, but some mammals are adapted for life at sea, in the air, in trees. The largest group of mammals, the placentals, have a placenta, Mammals range in size from the 30–40 mm bumblebee bat to the 30-meter blue whale. With the exception of the five species of monotreme, all modern mammals give birth to live young, most mammals, including the six most species-rich orders, belong to the placental group. The largest orders are the rodents and Soricomorpha, the next three biggest orders, depending on the biological classification scheme used, are the Primates, the Cetartiodactyla, and the Carnivora. Living mammals are divided into the Yinotheria and Theriiformes There are around 5450 species of mammal, in some classifications, extant mammals are divided into two subclasses, the Prototheria, that is, the order Monotremata, and the Theria, or the infraclasses Metatheria and Eutheria.
The marsupials constitute the group of the Metatheria, and include all living metatherians as well as many extinct ones. Much of the changes reflect the advances of cladistic analysis and molecular genetics, findings from molecular genetics, for example, have prompted adopting new groups, such as the Afrotheria, and abandoning traditional groups, such as the Insectivora. The mammals represent the only living Synapsida, which together with the Sauropsida form the Amniota clade, the early synapsid mammalian ancestors were sphenacodont pelycosaurs, a group that produced the non-mammalian Dimetrodon. At the end of the Carboniferous period, this group diverged from the line that led to todays reptiles. Some mammals are intelligent, with some possessing large brains, self-awareness, Mammals can communicate and vocalize in several different ways, including the production of ultrasound, scent-marking, alarm signals and echolocation. Mammals can organize themselves into fission-fusion societies and hierarchies, most mammals are polygynous, but some can be monogamous or polyandrous.
They provided, and continue to provide, power for transport and agriculture, as well as commodities such as meat, dairy products, wool. Mammals are hunted or raced for sport, and are used as model organisms in science, Mammals have been depicted in art since Palaeolithic times, and appear in literature, film and religion. Defaunation of mammals is primarily driven by anthropogenic factors, such as poaching and habitat destruction, Mammal classification has been through several iterations since Carl Linnaeus initially defined the class. No classification system is accepted, McKenna & Bell and Wilson & Reader provide useful recent compendiums. Though field work gradually made Simpsons classification outdated, it remains the closest thing to a classification of mammals