The animal kingdom
Claims that 'the more water you drink, the healthier you are' are not backed with scientific evidence. Pharmacology — It is the study of medicine or drug plants. Ecology — It is the study of inter—relationship between living organisms and their environment. Unlike animals which obrtain their food from what they eat plants obtain their nutrition from the soil and atmosphere. It is presumed that humans started collecting mushrooms as food in prehistoric times.
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Many of these funguslike organisms are included in the kingdom Chromista. Fungi are among the most widely distributed organisms on Earth and are of great environmental and medical importance. Many fungi are free-living in soil or water; others form parasitic or symbiotic relationships with plants or animals. Diseases caused by fungi and parasites are relatively uncommon in developed countries.
Fungal infections, also known as mycotic infections, may affect the skin surfaces or the internal organs of the body. The superficial mycotic infections are generally not serious and include….
Fungi are eukaryotic organisms; i. Historically, fungi were included in the plant kingdom; however, because fungi lack chlorophyll and are distinguished by unique structural and physiological features i. In addition, fungi are clearly distinguished from all other living organisms, including animals, by their principal modes of vegetative growth and nutrient intake. Fungi grow from the tips of filaments hyphae that make up the bodies of the organisms mycelia , and they digest organic matter externally before absorbing it into their mycelia.
While mushrooms and toadstools poisonous mushrooms are by no means the most numerous or economically significant fungi, they are the most easily recognized. The Latin word for mushroom , fungus plural fungi , has come to stand for the whole group.
Fungi other than mushrooms are sometimes collectively called molds, although this term is better restricted to fungi of the sort represented by bread mold. For information about slime molds, which exhibit features of both the animal and the fungal worlds, see protist. We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind. Your contribution may be further edited by our staff, and its publication is subject to our final approval.
Unfortunately, our editorial approach may not be able to accommodate all contributions. Our editors will review what you've submitted, and if it meets our criteria, we'll add it to the article. Coelomates have a cavity within the mesoderm , which can show one of two types of development: Most protostomes show schizocoelous development, in which the mesoderm proliferates from a single cell and divides to form a mass on each side of the body; the coelom arises from a split within each mass.
Deuterostomes show enterocoelic pouching, in which the endoderm evaginates and pinches off discrete pouches, the cavities of which become the coelom and the wall the mesoderm. The animals in these major divisions of the Bilateria differ in other fundamental ways, which are detailed below. Unlike sessile sponges or floating jellyfish , the Bilateria typically move actively in pursuit of food, although many members have further evolved into sessile or radial forms.
Directed movement is most efficient if sensory organs are located at the head or forward-moving end of the animal. Organs of locomotion are most efficiently arranged along both sides, a fact that defines the bilateral symmetry; many internal organs are not in fact paired, whereas muscle layers, limbs, and sensory organs almost invariably are. The diffuse nerve net of coelenterates coalesces into definite tracts or bundles, which run posteriorly from the anterior brain to innervate the structures of locomotion.
Flatworms phyla Platyhelminthes , Nemertea , and Mesozoa lack a coelom, although nemerteans have a fluid-filled cavity at their anterior, or head, end, which is used to eject the proboscis rapidly.
The lack of a fluid-filled cavity adjacent to the muscles reduces the extent to which the muscles can contract and the force they exert see below Support and movement. Because most also lack a circulatory system, supplying muscle tissues with fuel and oxygen can be no faster than the rate at which these substances diffuse through solid tissue. Flatworms are thus constrained to be relatively flat and comparatively small; parasitic worms, which do not locomote, can achieve immense lengths e.
The larger of the free-living flatworms have extensively divided guts, which reach to within a few cells of the muscles, thus compensating for the lack of a circulatory system.
Most flatworms have but one opening to the gut. Nemerteans, in addition to a coelom-like housing for their proboscis, have attained a one-way gut and a closed circulatory system. Both increase their ability to move food and oxygen to all parts of the body. Flatworms are considered to be the ancestors of all other Bilateria.
The pseudocoelomates include the nematodes, rotifers, gastrotrichs, and introverts. Some members of some other phyla are also, strictly speaking, pseudocoelomate. These four phyla of tiny body size many species no larger than the bigger protozoans are placed together in part because they lack mesoderm on the inner side of the body cavity.
Consequently, no tissue, muscular or connective, supports the gut within the coelomic fluid. For tiny organisms, this is advantageous for conservation of tissue: The inconspicuousness of most of these phyla has led to a slow advancement in understanding their phylogenetic position in the animal kingdom.
The advantage of a true coelom is the ability of the inner mesenteric mostly connective tissue layer to suspend the central gut in the middle of the animal. Otherwise, in those animals with a body cavity used in locomotion, gravity would pull the gut down and severely curtail body size. Coelomates have attained vastly larger body sizes than has any other group of animals. Within the coelomates, the coelom has been of variable significance to the form and diversity of the various phyla.
For example, it is essential for the burrowing abilities of annelids and related phyla. It has largely lost this significance in the arthropods, however, which have transferred locomotion to limbs supported by an exoskeleton rather than a coelomic hydroskeleton. Suspension is the main function of the coelom in vertebrates, which achieve the largest body sizes among animals by virtue of an endoskeleton that does not need to be shed during growth. The protostome coelomates acoelomates and pseudocoelomates are also protostomes include the mollusks, annelids, arthropods, pogonophorans, apometamerans, tardigrades, onychophorans, phoronids, brachiopods, and bryozoans.
Deuterostomes include the chaetognaths, echinoderms, hemichordates, and chordates. In early development protostome coelomates mostly differ from deuterostome coelomates in the following ways: Deuterostomes , in contrast, show indeterminate, radial cleavage, with the dividing cells becoming layered and the fate of early cells a product of where they are positioned later in development. The two phyla that have clearly dominated both land and sea since nearly the beginning of animal evolution are the arthropods and chordates, protostomous and deuterostomous coelomates, respectively.
A key to arthropod success has been the differentiation of many serially repeated parts, in particular jointed appendages with a rigid exoskeleton , to perform the varied functions necessary to maintain life. The exoskeleton, however, sets a moderate upper limit to body size. In contrast, vertebrates share all habitats with arthropods by virtue of the larger maximum size permitted by the development of an internal rigid skeleton.
More than does a coelom, the evolution of rigid, jointed skeletons has allowed these two phyla to dominate most animal communities. Large size is often competitively advantageous but unobtainable by many animals because of constraints of basic body plan. Intrinsically small animals sometimes become large in the same way that protozoans evolved into metazoans: This type of asexual sociality forms the colonoids of sponges, coelenterates, bryozoans, hemichordates, and tunicate chordates, all of which were primitively small, sessile filter feeders.
Staying together after asexual budding of new individuals gave a competitive edge to monopolizing available space. With slight modifications so that all individuals in the colony could share equally in the gains, these larger entities had the energy reserves necessary to outcompete smaller organisms for space. This type of sociality has evolved in ways that complicate the definition of individuality.
For instance, Portuguese men-of-war and their kin some hydrozoan coelenterates look and act like single individuals, yet their components develop as genetically identical units, each homologous to a whole jellyfish or polyp.
It is a question whether such an animal should be considered one individual or many. A different type of sociality emerged among mobile complex animals that can individually attain large size. In fact, the largest known living animals, the whales and elephants, comprise two of a very few mammalian orders that contain only social species.
The pattern of evolution on Earth has favoured sociality in the smallest and the largest mostly vertebrates of animals, albeit for different reasons. The smallest seek the advantages of being large, as protozoans did to form the first animals. The large animals can communicate; they spread out to find food, which all can share, and they protect one another.
Among the social groups of large animals, only humans have differentiated their functions to such an extent that their societies begin to behave as individuals. Insect societies show behaviours halfway between societies based on genetically identical members and those created by genetically different individuals; such properties largely reflect their intermediate degree of genetic relatedness.
Insects are more cooperative and show a greater degree of altruism than is true of vertebrate societies. We welcome suggested improvements to any of our articles. You can make it easier for us to review and, hopefully, publish your contribution by keeping a few points in mind.
Your contribution may be further edited by our staff, and its publication is subject to our final approval. Unfortunately, our editorial approach may not be able to accommodate all contributions. Our editors will review what you've submitted, and if it meets our criteria, we'll add it to the article. Please note that our editors may make some formatting changes or correct spelling or grammatical errors, and may also contact you if any clarifications are needed.
Aug 21, See Article History.