Animal
 Animalia (Animal) | |||
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| Representatives of various classes. | |||
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| Field | Eukaryota | ||
| Subdomain | Unikonta | ||
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| Animalia Linnaeus , 1758 | |||
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An animal (from Latin mind, or vital principle) is, the traditional classification , a living being heterotrophic , that is to say that he eats organic substances. We reserve the term animal today to complex multicellular beings, although it was long considered the protozoa as unicellular animals. Like all living beings, animals have similar with which they form a homogeneous group, called species.
In the phylogenetic classification currently in effect, the taxon of animals has been replaced by that of metazoans , which are defined as organisms eukaryotic multicellular mobile heterotrophs.
In common parlance, the term "animal" is often used to distinguish humans from the rest of the animal world, although the Homo sapiens is part of the animal kingdom. Similarly, but in common parlance, "animal" refers to the higher animals, as opposed to some animal forms are perceived as more primitive as sponges ( Porifera ), the corals , or actiniaires, or sea anemones.
Summary |
Zoology
Physiology common
Like all living organisms, animals need water , an oxidant which is exclusively the oxygen for these species, and organic materials from other organizations because they can not produce themselves from molecules not derived from living. They say they are chemo-organotrophic and when organic matter is from another animal, it is called predation. This food has three objectives: to provide substances which are used to create other cells produce substances useful to create molecules and structures in the body (bones, hair, tears, smells ...), and especially provide energy.
Like all living organisms, the water element is that animals are more difficult to pass. Besides the fact that cells consist mainly of water, water is necessary for most biochemical reactions where it serves as solvent. But in addition, she serves for the evacuation of nitrogenous waste produced by the metabolism of proteins that must be eliminated. The animals are, like other non-aquatic species even, also face problems related to osmoregulation. The need for water means having a system of osmotic regulation.
They need to get their food by moving or grasping, and through a digestive system , to separate the organisms necessary substances that are useful, and then digest them. The acquisition of oxygen used to oxidize carbohydrates to produce chemical energy, is also a priority for most animals. Most species have a respiratory system to absorb oxygen. The oxygen, water and various substances are brought into the cells, and the byproducts are removed unnecessary ( excretion ) through various circulatory systems. The problems posed by different environments require specific adaptations. Thus the acquisition of oxygen for a terrestrial organism is less difficult than the acquisition of the water. The reverse is true in an aquatic environment. To acquire these substances essential for life, most animals use the organs of perception. They also use their senses to escape predators. To absorb the substances necessary for life that draws other living organisms, the animal needs a digestive system and therefore a system of excretion.
The functions of reproduction are also important in animals that are primarily sexual , but some species like the Hydra can also reproduce a manner asexually (by budding in his case). The reproductive system is vital to the species only, otherwise it will inevitably disappear after some time.
The animals also have very different systems of locomotion , of perception.
In addition, they have different systems of circulation of fluid inside the body and coordination of the various cells. The aging does not appear to be part of the fundamental characteristics, as some species of sponges do not age Classification by internal organization The internal organization of the animals can be very complex variable, since the colony of cells that are relatively amorphous sponges, to very complex organizations of insects or vertebrates. Technically, the animals are organisms eukaryotic multicellular (except Myxozoa ), which differentiates them from Bacteria and Protista and without chloroplasts ( heterotrophic ), which distinguishes them from plants and algae. They also differ from Mycota. They are the only organisms that pass through a stage in their development by a blastocyst. They are able to move, sometimes only as larvae (the case of sponges and many invertebrates benthic attached to the substrate). They constitute the kingdom Animalia, the domain subdivision Eukaryota. Animals (or metazoans ) are one of the types of eukaryotes to have developed a method multicellular , like plants , some fungi , and algae brown as opposed to unicellular that include yeasts, algae and other fungi, protozoa, and be living together in the Prokaryote , consisting of Eubacteria and Archaea. It differs, depending on the complexity of internal organization, or four levels Classification An estimated 1.75 million the number of living species currently described by the scientists. It is possible that there are 2 to 40 times more non-living being described. According to French daily Le Figaro in 2008, scientists estimate that we know that 20-30% of animal species living on Earth. "We are unable to assess their number more than a factor of ten closely. (..) Are recorded each year, all animals combined, 15,000 new species. " . The number of extinct species is obviously even greater. There are large general characteristics that classify living things into phyla. According to the theory of evolution , the current animal phyla are the surviving groups of about a hundred existing Cambrian , they are known only by their fossils. Animal cells are heterotrophic , that is to say they must eat to survive, unlike plants. The survival of an animal goes through a constant concern: how to eat? Strategy sponge is simply filter water through them, to capture prey. This strategy requires neither complex structure or coordinated movement. Sponges ( Porifera ) are organizing the simplest: they are virtually undifferentiated cell colonies without actual internal structures or operation. They are animals without nervous system or gastrointestinal tract. Their body is formed by two cell layers ( ectoderm and endoderm ). The transition from one level to a sponge-like anemone-type organization continues to meet the constant question: how to eat? The formula developed by this group is to push food into a stomach ( gastric cavity ) where it can be digested without saving. This innovative approach allows to feed on larger prey (such as sponges can not filter). In the progressive acquisition of animal features, this development implies two things: the cells specialize (with the acquisition of nerve and muscle cells for coordinated movements) and the agency gains the ability to take a definite shape ( morphogenesis ) for effective tentacles can grow their prey to a stomach cavity effective. The worm-like organization is a new answer to the central question of the animal kingdom: how to eat? The basic strategy of organizations like "worm" (worm) is to move to get food, instead of waiting until it passes within range. This strategy makes particular use of organic waste, which can be highly nutritious, but not moving. Passed the sponges and polyps, all complex organisms are bilaterians , which are derived from a basic pattern: the tube. The development is organized around an axis head / tail first, and back / stomach on the other. These two axes lead to an overall plan where the right and left tend to be symmetrical, hence the name of bilaterians. The easiest to mark a qualitative step further compared to cnidarians : nerve cells are organized into a coherent nervous system, the prototype of what would become the brain in higher animals. It is this ability to move and react to the environment which is regarded as the degree of organization is the first stage vermiform actually "animal". The second major invention of the verse (missing in flatworms) is the presence of an alimentary canal and digestive function: at one end, a mouth absorbs food, the other, an anus excretes waste. Between the "outer tube" that forms the skin ( ectoderm ) and the "inner tube ( endoderm ) which is the alimentary canal, an intermediate tissue, the mesoderm , can develop and train internal organs increasingly complex. The invention of the digestive tract from the stomach cavity ancestral seems to have been made twice. In protostomes , the two openings of the alimentary canal is formed from the blastopore , whose lips are close to form a channel for longitudinal welding. In deuterostomes , the opening of the blastopore becomes the anus , the alimentary canal is formed by a piercing that will evolve further towards the mouth. The worms are the source of a second major invention of evolution: the segmentation ( metamerism ). This invention also appears to have been made in several different branches. The discovery of the digestive tract and the ability to move (crawling) was the winning formula: wormlike organisms are quite versatile and can serve as a basis for very different lifestyles. This is called a radiative explosion : from a basic pattern common forms are taking divergent paths, as if radiating from a central explosion. All other schemes rely on more sophisticated organization such fundamental: they are a little to complicated. The main groups within the organization level worm are: The level of organization-type worm is not maintained in all bilaterians. Organizations such as tunicates are more like forms of sponges or corals as worms, which is usually the case for returning forms to a vegetative mode of life. Finally, this form of organization becomes more complex in three ways, which can leave the hard parts of fossil The mollusks evolved from a worm-like organization. The feature that seems to have conditioned the primitive molluscs appears to be the shield, to protect themselves from predators assets: acquisition of calcareous plates protecting their backs. These primitive molluscs should therefore resemble Polyplacophora (a kind of snail that can be rolled into a ball like a hedgehog or a woodlouse), but this type is now very marginal. Molluscs include the following important classes: On the general formula of worms, arthropods have superimposed several innovations: This winning formula is the general form of the centipede. She was immediately caused a new explosion radiation, which explored various options to turn any group of jaw legs, antennae, legs specialized or regress in the left tail. The arthropod is by far the one that has more species and more individuals across the animal kingdom. There are over a million and half of current species of arthropods. The central question seems to have structured its distribution is: how many legs does it take to move? The insects are among the arthropods. Their body is composed of three parts: head, thorax, abdomen. They have six legs, four wings and two antennae. This is a general description, evolution has done that by specialization, some items may be atrophied. Insects are subservient to the land. The only insects are known marine water striders of the genus Halobates. They are found in almost all climates, from the warmer to colder. The essential feature that originally structured this order was the ability to swim in water (did not know what to do or primitive mollusks nor arthropod primitive). But this capacity has not led to an explosion radiation: by itself, it does not provide a sufficient functional autonomy so that organizations can specialize in a very free. The history of this lineage appears laborious: the gradual discovery of the head and jaw, then the exploration stage to members of tetrapod, and finally, the conquest of the air environment, resulting in the explosion radiative dinosaurs finally versatile. The tetrapods , animals with four members, had a blast radiation after having conquered the ability to move on land. However, some groups of species such as cetaceans and snakes do not keep following their evolution, as the remains of members. Tetrapods include animal size really different from mammals to the blue whale is the largest known animal of all time but they represent only a small fraction of both species (more than 2%) and the biomass. Despite this, they are among the species best known to man which it belongs. Although man has, since Aristotle at least, tried to group the different species according to homogeneous groups, it is able to understand the phylogeny of this group until the late nineteenth century. We consider now that this group is composed of amphibians , the Sauropsida (including reptiles and birds ) and Synapsida (including mammals ). These tetrapods are characterized by bare skin. Many of them lead to the adult life phase alternating aquatic and terrestrial phase. These tetrapods are characterized by the presence of welded shells. These tetrapods are characterized by the presence of feathers. The explosion radiative mammals , most recently, has been following the disappearance of the dinosaurs. Mammals are generally identifiable by their skin, at least partially covered with hair. The fact that females nurse their young is also a characteristic of this group. Various sciences seek to study the animal world such as zoology , which splits into a multitude of specialties, medicine veterinary , but also a way derivative of paleontology , the biology , and microbiology and agronomy for his involvement economical. the risk of extinction Near Threatened World Conservation Union Since the emergence of life, many species are disappearing while others evolve and provide new species. During the history of life, there have been mass extinctions (there are usually distinguished five major), especially after some cataclysm. These extinctions are followed by explosions of radiative, that is to say a surge of new species. The man trying to tame nature, fostering a necessarily limited number of species, tended to reduce the number of biomes. On the other hand, the pollution generated by industry and the consumer society also destabilize biomes and reduce the number of species. The larger species are particularly affected so have considered that the number of species that can be extinguished in the coming years could be massive. The current extinction is called the Holocene extinction and the pace would be 10 to 100 times higher than that of past extinctions. Many laws designed to protect wildlife, habitat impacts of the actions of humans. Some are more specific to the protection of natural environments, others more specific to protect the animals from the malice of roadkill , overexploitation or risk of poisoning, etc.. There are also several types of organizations for animal protection and conservation , for example: Various guides or codes of good practice, including in France on the green and blue or how to reduce roadkill or disarm some traps Animal Transport in Europe On 13 December 1968 was signed in Paris the European Convention on the Protection of Animals during International Transport, which regulates the transportation of pets. The CITES manages the rights of ownership of wild animals. On 22 December 2004 the European Union has done a complete overhaul of rules on welfare of animals during transport. In this new regulation, it identifies all stakeholders and their respective responsibilities, it strengthens the surveillance measures and provides for stricter rules for long journeys and vehicles. However, some animal protection organizations, including the CIWF , denouncing the conditions of transport of animals over long distances, sometimes from one country to another for economic reasons, to be fattened or slaughtered . The Switzerland meanwhile, does not allow the transit of live animals for slaughter, by road, from the Europe on its territory , because of tougher laws on the subject adopted by Switzerland . Much of infectious diseases or due to a prion pathogen can be carried by domestic or wild animals. In a rapidly globalizing world, the WHO , the FAO and the OIE encourages better monitoring landscape epidemiology and establishment of security arrangements for trade or sale of animals (dead or alive), who face also on animal trafficking. Since the Paleolithic , to ensure the presence of animals that can accommodate him, man has domesticated a number of species and created farms. He was able, by selection of crosses , change the characteristics of certain species and to create hybrid animals to respond more effectively to their needs. The animal is a source of income for humans. The uses of the animal will transport food, to clothing. The man also uses animals in his spare time raising pets , filming them, discovering them in the context of zoos or safari. These last two activities are becoming more respectful of the preservation of animals in their natural environment by encouraging the breeding of endangered species and study for the parks. In attempting to provide additional income to local populations, the latter thus more interest in preserving animal life for safaris. Some people refuse the exploitation of animals and refuse to eat meat, so Vegetarianism. Others refuse to eat any products derived from animal exploitation (egg, milk, honey ...), it is Vegan. The vegans in turn, generalize this choice to the use of all animal products in daily life (wool, leather, tested products, wax, fur, silk ...). In the West, Aristotle divided the living world between animals and plants. His design, called immutability is not very different from that of the preceding scholars and theologians will be taken over by Christians, who by a literal reading of the Bible , believed that the universe and the known world had been created in a weeks , and it was not appropriate to put this idea into question. The animals were there to serve man. However from the Renaissance, some ideas are challenged. While the work of Carl von Linn in the eighteenth century seeking to systematically classify all living species by giving them a unique name and exact ( binomial name ), Jean-Baptiste Lamarck , and especially Charles Darwin , elaborate theories of evolution species. Of these theories, especially with that of Darwin will be born a controversy with creationists often claim that their commitment to a biblical vision of Christian origin of life. Darwin's theory is particularly criticized because it is not only the human animal, but also the result of evolution by natural selection whose sexuality. Linnaeus had originally defined three kingdoms separated themselves into the following groups: Vermes , Insecta , Pisces , Amphibia , Aves , and Mammalia. This ranking will gradually evolve over the discoveries in zoology or paleontology. This classification is based on characters anatomical and physiological tends to become a phylogenetic classification , that is to say the closest possible to the genetic tree. The Christian religion clearly separates the human from the animal kingdom in its nature (in the story of Genesis , man is the only being created in the image of God ) as in its function (God imparts to human nature for their livelihood, mankind must "dominate" nature) . Religions animist fully integrate animal and human in nature, without loss of continuity for all things of nature are endowed with a soul. The French philosopher Rene Descartes (1596-1650) is dualistic , distinguishing clearly two forms of reality: thought (the soul ) and extent (the area ). The animal, which has no soul, is thus a " machine ", a PLC perfected. This is the theory of animal-machine . The French philosopher Jean-Jacques Rousseau (1712-1778) also seen in any animal, including humans, a "smart machine". But he distinguishes humans from animals in that "Nature alone is all in the operations of the beast, whereas man contributes to his own, as a free agent." The difference here is the thought and the ability of intiative and freedom of man who follows . Men since time immemorial, have lent animal virtues or characteristics either human or divine. And some animals have become symbols, many stories are anthropomorphic and finally some species of animals have also been deified by certain peoples. Animals in the fictional world are still very abundant. The martial art of animal imitates animals, for their extremely effective martial. Number of species
General classification
Branch Known Species Examples Arthropoda 1.2 million Insects , spiders , crabs Mollusca 100 000 to 110 000 Snails , mussels , octopus Nematoda 90 000 to 120,000 Ascaris Chordata 47 200 Mammals , birds , fish , reptiles Platyhelminthes 15 000 to 20,000 Tapeworm Annelida 15 000 , Earthworms , leeches Cnidaria 9000 to 10 000 Medusae and Polyps Echinodermata 6000 , Urchins , starfish Porifera 4300 Sponges Other (27) approximately 100 000 To marine constituents of zooplankton , limestone producers Elementary Forms
Sponge (colony cell)
Polyp: hydra, coral and jellyfish
Worm (mobility and digestive tract)
Explosion radiative vermiform
Graduate Forms
Molluscs
Arthropods
Insects
Towards swimmers: fish
The tetrapods
Amphibians
Reptiles
Birds
Mammals
Threats and Protection
Disappearance of Species
Conservation status Extinction Endangered At lower risk
Least Concern See also
IUCN Red List
Protected species 
Portal Nature Conservancy
v of m Protection of Animals
Health
Humans and other animals
Use by humans
Eye of man
History of classification
Religion
Philosophy
The Gaia hypothesis originally advanced by the ecologist English James Lovelock in 1970 , but also raised by other scientists before him, sees all living things on Earth as a vast organism (called Gaia , after the name of Titan of Greek mythology personified the Earth), achieving self-regulation of its components to promote life. Symbolism
References
Bibliography
See also
Related articles
Miscellaneous
Classification detailed phylogenetic
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