1.
Pine
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A pine is any conifer in the genus Pinus, /ˈpiːnuːs/, of the family Pinaceae. Pinus is the genus in the subfamily Pinoideae. The Plant List compiled by the Royal Botanic Gardens, Kew and Missouri Botanical Garden accepts 126 species names of pines as current, together with 35 unresolved species, the modern English name pine derives from Latin pinus, which some have traced to the Indo-European base *pīt- ‘resin’. Before the 19th century, pines were often referred to as firs, the genus is divided into three subgenera, which can be distinguished by cone, seed, and leaf characters, Pinus subg. Pinus, the yellow, or hard pine group, generally harder wood. Ducampopinus, the foxtail or pinyon group Pinus subg, strobus, the white, or soft pine group, generally with softer wood and five needles per fascicle Most regions of the Northern Hemisphere host some native species of pines. One species crosses the equator in Sumatra to 2°S, in North America, various species occur in regions at latitudes from as far north as 66°N to as far south as 12°N. Various species have been introduced to temperate and subtropical regions of both hemispheres, where they are grown as timber or cultivated as ornamental plants in parks, a number of such introduced species have become invasive and threaten native ecosystems. Pine trees are evergreen, coniferous trees growing 3–80 m tall. The smallest are Siberian dwarf pine and Potosi pinyon, and the tallest is a 81.79 m tall ponderosa pine located in southern Oregons Rogue River-Siskiyou National Forest, the bark of most pines is thick and scaly, but some species have thin, flaky bark. The branches are produced in regular pseudo whorls, actually a very tight spiral, the spiral growth of branches, needles, and cone scales are arranged in Fibonacci number ratios. The new spring shoots are sometimes called candles, they are covered in brown or whitish bud scales and point upward at first, then turn green. These candles offer foresters a means to evaluate fertility of the soil, pines are long-lived, and typically reach ages of 100–1,000 years, some even more. The longest-lived is the Great Basin bristlecone pine, Pinus longaeva, one individual of this species, dubbed Methuselah, is one of the worlds oldest living organisms at around 4,600 years old. This tree can be found in the White Mountains of California, an older tree, now cut down, was dated at 4,900 years old. It was discovered in a grove beneath Wheeler Peak and it is now known as Prometheus after the Greek immortal, pines have four types of leaf, Seed leaves on seedlings, born in a whorl of 4–24. Juvenile leaves, which follow immediately on seedlings and young plants, 2–6 cm long, single, green or often blue-green and these are produced for six months to five years, rarely longer. Scale leaves, similar to bud scales, small, brown and non-photosynthetic, needles, the adult leaves, are green and bundled in clusters called fascicles
2.
Plant
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Plants are mainly multicellular, predominantly photosynthetic eukaryotes of the kingdom Plantae. The term is generally limited to the green plants, which form an unranked clade Viridiplantae. This includes the plants, conifers and other gymnosperms, ferns, clubmosses, hornworts, liverworts, mosses and the green algae. Green plants have cell walls containing cellulose and obtain most of their energy from sunlight via photosynthesis by primary chloroplasts and their chloroplasts contain chlorophylls a and b, which gives them their green color. Some plants are parasitic and have lost the ability to produce amounts of chlorophyll or to photosynthesize. Plants are characterized by sexual reproduction and alternation of generations, although reproduction is also common. There are about 300–315 thousand species of plants, of which the great majority, green plants provide most of the worlds molecular oxygen and are the basis of most of Earths ecologies, especially on land. Plants that produce grains, fruits and vegetables form humankinds basic foodstuffs, Plants play many roles in culture. They are used as ornaments and, until recently and in variety, they have served as the source of most medicines. The scientific study of plants is known as botany, a branch of biology, Plants are one of the two groups into which all living things were traditionally divided, the other is animals. The division goes back at least as far as Aristotle, who distinguished between plants, which generally do not move, and animals, which often are mobile to catch their food. Much later, when Linnaeus created the basis of the system of scientific classification. Since then, it has become clear that the plant kingdom as originally defined included several unrelated groups, however, these organisms are still often considered plants, particularly in popular contexts. When the name Plantae or plant is applied to a group of organisms or taxon. The evolutionary history of plants is not yet settled. Those which have been called plants are in bold, the way in which the groups of green algae are combined and named varies considerably between authors. Algae comprise several different groups of organisms which produce energy through photosynthesis, most conspicuous among the algae are the seaweeds, multicellular algae that may roughly resemble land plants, but are classified among the brown, red and green algae. Each of these groups also includes various microscopic and single-celled organisms
3.
Pinophyta
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The Pinophyta, also known as Coniferophyta or Coniferae, or commonly as conifers, are a division of vascular land plants containing a single class, Pinopsida. They are gymnosperms, cone-bearing seed plants, all extant conifers are perennial woody plants with secondary growth. The great majority are trees, though a few are shrubs, examples include cedars, Douglas firs, cypresses, firs, junipers, kauri, larches, pines, hemlocks, redwoods, spruces, and yews. As of 1998, the division Pinophyta was estimated to contain eight families,68 genera, although the total number of species is relatively small, conifers are ecologically important. They are the dominant plants over large areas of land, most notably the taiga of the Northern Hemisphere, boreal conifers have many wintertime adaptations. The narrow conical shape of northern conifers, and their downward-drooping limbs, many of them seasonally alter their biochemistry to make them more resistant to freezing. While tropical rainforests have more biodiversity and turnover, the conifer forests of the world represent the largest terrestrial carbon sink. Conifers are of economic value for softwood lumber and paper production. The earliest conifers in the record date to the late Carboniferous period, possibly arising from Cordaites. Pinophytes, Cycadophytes, and Ginkgophytes all developed at this time, an important adaptation of these gymnosperms was allowing plants to live without being so dependent on water. Other adaptations are pollen and the seed, which allows the embryo to be transported and developed elsewhere, Conifers appear to be one of the taxa that benefited from the Permian–Triassic extinction event, and were the dominant land plants of the Mesozoic. They were overtaken by the plants, which first appeared in the Cretaceous. They were the food of herbivorous dinosaurs, and their resins and poisons would have given protection against herbivores. Reproductive features of modern conifers had evolved by the end of the Mesozoic era, Conifer is a Latin word, a compound of conus and ferre, meaning the one that bears cone. A descriptive name in use for the conifers is Coniferae. Alternatively, descriptive botanical names may also be used at any rank above family and this means that if conifers are considered a division, they may be called Pinophyta or Coniferae. As a class they may be called Pinopsida or Coniferae, as an order they may be called Pinales or Coniferae or Coniferales. Conifers are the largest and economically most important component group of the gymnosperms, the division Pinophyta consists of just one class, Pinopsida, which includes both living and fossil taxa
4.
Rosin
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It is semi-transparent and varies in color from yellow to black. At room temperature rosin is brittle, but it melts at stove-top temperature and it chiefly consists of various resin acids, especially abietic acid. The term colophony comes from colophonia resina, Latin for resin from Colophon, Rosin is an ingredient in printing inks, photocopying and laser printing paper, varnishes, adhesives, soap, paper sizing, soda, soldering fluxes, and sealing wax. Rosin can be used as an agent in medicines and chewing gum. It is denoted by E number E915, a related glycerol ester can be used as an emulsifier in soft drinks. In pharmaceuticals, rosin forms an ingredient in several plasters and ointments, in industry, rosin is a flux used in soldering. It is frequently seen as the burnt or clear residue around new soldering, a mixture of pitch and rosin is used to make a surface against which glass is polished when making optical components such as lenses. Rosin is added in quantities to traditional linseed oil/sand gap fillers. When mixed with waxes and oils, rosin is the ingredient of mystic smoke, a gum which. Extra substances such as beeswax, gold, silver, tin, or meteoric iron are added to the rosin to modify its stiction/friction properties. Powdered rosin can be applied to new hair, for example with a pad or cloth. Rosin is often applied to the bow before playing the instrument, lighter rosin is generally preferred for violins and violas, and in high-humidity climates, while darker rosins are preferred for cellos, and for players in cool, dry areas. There are also specific, distinguishing types for basses—for more see Bow, violin rosin can be applied to the bridges in other musical instruments, such as the banjo and banjolele, in order to prevent the bridge from moving during vigorous playing. Ballet, flamenco, and Irish dancers are known to rub the tips and it was at one time used in the same way in fencing and is still used as such by boxers. Gymnasts and team handball players use it to improve grip, rock climbers have used it in some locations, but it fouls the rock, so usage is now highly discouraged. Olympic weightlifters rub the soles of their boots in rosin to improve traction on the platform. It is applied onto the line of drag racing courses used to improve traction. Bull riders rub rosin on their rope and glove for additional grip, baseball pitchers and ten-pin bowlers may use a small cloth bag of powdered rosin for better ball control
5.
Medicinal plants
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Medicinal plants, medicinal herbs, or simply herbs have been identified and used from prehistoric times. Plants make many chemical compounds for biological functions, including defence against insects, fungi, over 12,000 active compounds are known to science. These chemicals work on the body in exactly the same way as pharmaceutical drugs. However, since a plant may contain many substances, the effects of taking a plant as medicine can be complex. The earliest historical records of herbs are found from the Sumerian civilisation, drug research makes use of ethnobotany to search for pharmacologically active substances in nature, and has in this way discovered hundreds of useful compounds. These include the common drugs aspirin, digoxin, quinine, the compounds found in plants are of many kinds, but most are in four major biochemical classes, the alkaloids, glycosides, polyphenols, and terpenes. Medicinal plants are used to treat disease in non-industrialized societies. The annual global export value of plants in 2012 was over US$2.2 billion. Plants, including many now used as herbs and spices, have been used as medicines from prehistoric times. Spices have been used partly to counter food spoilage bacteria, especially in hot climates, angiosperms were the original source of most plant medicines. Human settlements are surrounded by weeds useful as medicines, such as nettle, dandelion. Humans were not alone in using herbs as medicines, some such as non-human primates, monarch butterflies. Plant samples from prehistoric sites are among the lines of evidence that Paleolithic peoples had knowledge of herbal medicine. The mushroom was used to treat whipworm. In ancient Sumeria, hundreds of plants including myrrh and opium are listed on clay tablets. The ancient Egyptian Ebers Papyrus lists over 800 plant medicines such as aloe, cannabis, castor bean, garlic, juniper, the Chinese pharmacopoeia, the Shennong Ben Cao Jing records plant medicines such as chaulmoogra for leprosy, ephedra, and hemp. This was expanded in the Tang Dynasty Yaoxing Lun, in the fourth century BC, Aristotles pupil Theophrastus wrote the first systematic botany text, Historia plantarum. In the Early Middle Ages, Benedictine monasteries preserved medical knowledge in Europe, translating and copying classical texts, hildegard of Bingen wrote Causae et Curae on medicine
6.
Tradition
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A tradition is a belief or behavior passed down within a group or society with symbolic meaning or special significance with origins in the past. Common examples include holidays or impractical but socially meaningful clothes, there are about 150 new traditions made each year. Traditions can persist and evolve for thousands of years—the word tradition itself derives from the Latin tradere or traderer literally meaning to transmit, to hand over, to give for safekeeping. While it is assumed that traditions have ancient history, many traditions have been invented on purpose, whether that be political or cultural. Various academic disciplines also use the word in a variety of ways, one way tradition is used more simply, often in academic work but elsewhere also, is to indicate the quality of a piece of information being discussed. For example, According to tradition, Homer was born on Chios and this tradition may never be proven or disproven. In another example, King Arthur, by tradition a true British king, has inspired many well loved stories, of course whether they are documented fact or not does not decrease their value as cultural history and literature. Aside from this use in describing the quality of information, various scholarly fields define the term differently, for example, anthropology and biology have each defined tradition it more precisely than in conventional, as described below, in order to facilitate scholarly discourse. The concept of tradition, as the notion of holding on to a time, is also found in political and philosophical discourse. For example, it is the basis of the concept of traditionalism. In artistic contexts, tradition is used to decide the correct display of an art form, for example, in the performance of traditional genres, adherence to guidelines dictating how an art form should be composed are given greater importance than the performers own preferences. A number of factors can exacerbate the loss of tradition, including industrialization, globalization, in response to this, tradition-preservation attempts have now been started in many countries around the world, focusing on aspects such as traditional languages. Tradition is usually contrasted with the goal of modernity and should be differentiated from customs, conventions, laws, norms, routines, rules and similar concepts. The English word tradition comes from the Latin traditio, the noun from the verb traderere or tradere, it was used in Roman law to refer to the concept of legal transfers. As with many other terms, there are many definitions of tradition. Tradition can also refer to beliefs or customs that are Prehistoric, with lost or arcane origins, originally, traditions were passed orally, without the need for a writing system. Tools to aid this process include poetic devices such as rhyme, the stories thus preserved are also referred to as tradition, or as part of an oral tradition. Even such traditions, however, are presumed to have originated at some point, Traditions are often presumed to be ancient, unalterable, and deeply important, though they may sometimes be much less natural than is presumed
7.
Mevalonate pathway
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The mevalonate pathway, also known as the isoprenoid pathway or HMG-CoA reductase pathway is an essential metabolic pathway present in eukaryotes, archaea, and some bacteria. The mevalonate pathway begins with acetyl-CoA and ends with the production of IPP and DMAPP and it is best known as the target of statins, a class of cholesterol lowering drugs. Statins inhibit HMG-CoA reductase within the mevalonate pathway, the mevalonate pathway of eukaryotes, archaea, and eubacteria all begin the same way. The sole carbon feed stock of the pathway is acetyl-CoA, the first step condenses two acetyl-CoA molecules to yield acetoacetyl-CoA. This is followed by a condensation to form HMG-CoA. These first 3 enzymatic steps are called the upper mevalonate pathway, the lower mevalonate pathway which converts -mevalonate into IPP and DMAPP has 3 variants. In eukaryotes, mevalonate is phosphorylated twice in the 5-OH position, in some archaea such as Haloferax volcanii, mevalonate is phosphorylated once in the 5-OH position, decarboxylated to yield isopentenyl phosphate, and finally phosphorylated again to yield IPP. A third mevalonate pathway variant found in Thermoplasma acidophilum, phosphorylates mevalonate at the 3-OH position followed by phosphorylation at the 5-OH position, the resulting metabolite, mevalonate-3, 5-bisphosphate, is decarboxylated to IP, and finally phosphorylated to yield IPP. Several key enzymes can be activated through DNA transcriptional regulation on activation of SREBP, regulation of this pathway is also achieved by controlling the rate of translation of the mRNA, degradation of reductase and phosphorylation. The output of both the pathway and the MEP pathway are the same, IPP and DMAPP, however the enzymatic reactions to convert acetyl-CoA into IPP are entirely different. In higher plants, the MEP pathway operates in plastids while the mevalonate pathway operates in the cytosol, examples of bacteria that contain the MEP pathway include Escherichia coli and pathogens such as Mycobacterium tuberculosis. Rensselaer Polytechnic Institute page on cholesterol synthesis
8.
Apicomplexa
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The Apicomplexa are a large phylum of parasitic alveolates. Most of them possess a form of organelle that comprises a type of plastid called an apicoplast. The organelle is an adaptation that the apicomplexan applies in penetration of a host cell, the Apicomplexa are unicellular and spore-forming. All species are endoparasites of animals, except Nephromyces, a symbiont in marine animals. Motile structures such as flagella or pseudopods are present only in certain gamete stages, the Apicomplexa are a diverse group that includes organisms such as the coccidia, gregarines, piroplasms, haemogregarines, and plasmodia. The Apicomplexa comprise the bulk of what used to be called the Sporozoa, most of the Apicomplexa are motile, however, by use of a gliding mechanism that uses adhesions and small static myosin motors. The other main lines were the Ascetosporea, the Myxozoa, sometimes, the name Sporozoa is taken as a synonym for the Apicomplexa, or occasionally as a subset. All members of this phylum have an infectious stage — the sporozoite — which possesses three distinct structures in an apical complex, the apical complex consists of a set of spirally arranged microtubules, a secretory body and one or more polar rings. Additional slender electron-dense secretory bodies surrounded by one or two rings may also be present. This structure gives the phylum its name, a further group of spherical organelles is distributed throughout the cell rather than being localized at the apical complex and are known as the dense granules. These typically have a diameter around 0.7 μm. Secretion of the content takes place after parasite invasion and localization within the parasitophorous vacuole. Other morphological findings common to all members of this phylum include, flagella are found only in the motile gamete. These are posteriorly directed and vary in number, although hemosporidians and piroplasmids have normal triplets of microtubules in their basal bodies, coccidians and gregarines have nine singlets. Centrioles, chloroplasts, ejectile organelles, and inclusions are absent, colourless plastids are present in some species. The cell is surrounded by a pellicle of three membrane layers penetrated by micropores, replication, Mitosis is usually closed, with an intranuclear spindle, in some species, it is open at the poles. Cell division is usually by schizogony, mobility, Apicomplexans have a unique gliding capability which enables them to cross through tissues and enter and leave their host cells. This gliding ability is made possible by the use of adhesions, other features common to this phylum are a lack of cilia, sexual reproduction, use of micropores for feeding, and the production of oocysts containing sporozoites as the infective form
9.
Bacteria
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Bacteria constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a number of shapes, ranging from spheres to rods, Bacteria were among the first life forms to appear on Earth, and are present in most of its habitats. Bacteria inhabit soil, water, acidic hot springs, radioactive waste, Bacteria also live in symbiotic and parasitic relationships with plants and animals. Most bacteria have not been characterised, and only half of the bacterial phyla have species that can be grown in the laboratory. The study of bacteria is known as bacteriology, a branch of microbiology, There are typically 40 million bacterial cells in a gram of soil and a million bacterial cells in a millilitre of fresh water. There are approximately 5×1030 bacteria on Earth, forming a biomass which exceeds that of all plants, Bacteria are vital in many stages of the nutrient cycle by recycling nutrients such as the fixation of nitrogen from the atmosphere. The nutrient cycle includes the decomposition of bodies and bacteria are responsible for the putrefaction stage in this process. In March 2013, data reported by researchers in October 2012, was published and it was suggested that bacteria thrive in the Mariana Trench, which with a depth of up to 11 kilometres is the deepest known part of the oceans. Other researchers reported related studies that microbes thrive inside rocks up to 580 metres below the sea floor under 2.6 kilometres of ocean off the coast of the northwestern United States. According to one of the researchers, You can find microbes everywhere—theyre extremely adaptable to conditions, the vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, though many are beneficial particularly in the gut flora. However several species of bacteria are pathogenic and cause diseases, including cholera, syphilis, anthrax, leprosy. The most common fatal diseases are respiratory infections, with tuberculosis alone killing about 2 million people per year. In developed countries, antibiotics are used to treat infections and are also used in farming, making antibiotic resistance a growing problem. Once regarded as constituting the class Schizomycetes, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus and these evolutionary domains are called Bacteria and Archaea. The ancestors of modern bacteria were unicellular microorganisms that were the first forms of life to appear on Earth, for about 3 billion years, most organisms were microscopic, and bacteria and archaea were the dominant forms of life. In 2008, fossils of macroorganisms were discovered and named as the Francevillian biota, however, gene sequences can be used to reconstruct the bacterial phylogeny, and these studies indicate that bacteria diverged first from the archaeal/eukaryotic lineage. Bacteria were also involved in the second great evolutionary divergence, that of the archaea, here, eukaryotes resulted from the entering of ancient bacteria into endosymbiotic associations with the ancestors of eukaryotic cells, which were themselves possibly related to the Archaea
10.
Carotenoid
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Carotenoids, also called tetraterpenoids, are organic pigments that are produced by plants and algae, as well as several bacteria and fungi. Carotenoids can be produced from fats and other basic organic metabolic building blocks by all these organisms, the only animals known to produce carotenoids are aphids and spider mites, which acquired the ability and genes from fungi. Carotenoids from the diet are stored in the fatty tissues of animals, there are over 600 known carotenoids, they are split into two classes, xanthophylls and carotenes. All are derivatives of tetraterpenes, meaning that they are produced from 8 isoprene molecules, in general, carotenoids absorb wavelengths ranging from 400-550 nanometers. This causes the compounds to be colored yellow, orange. Carotenoids are the dominant pigment in autumn leaf coloration of about 15-30% of tree species, carotenoids serve two key roles in plants and algae, they absorb light energy for use in photosynthesis, and they protect chlorophyll from photodamage. Carotenoids that contain unsubstituted beta-ionone rings have vitamin A activity, CRT is the gene cluster responsible for the biosynthesis of carotenoids. Carotenoids belong to the category of tetraterpenoids, structurally, carotenoids take the form of a polyene hydrocarbon chain which is sometimes terminated by rings, and may or may not have additional oxygen atoms attached. Carotenoids with molecules containing oxygen, such as lutein and zeaxanthin, are known as xanthophylls, the unoxygenated carotenoids such as α-carotene, β-carotene, and lycopene, are known as carotenes. Carotenes typically contain only carbon and hydrogen, and are in the subclass of unsaturated hydrocarbons, probably the most well-known carotenoid is the one that gives this second group its name, carotene, found in carrots and are responsible for their bright orange color. Dried carrots have the highest amount of carotene of any food per 100 gram serving, vietnamese Gac fruit contains the highest known concentration of the carotenoid lycopene. Their color, ranging from yellow through bright orange to deep red, is directly linked to their structure. Xanthophylls are often yellow, hence their class name, the double carbon-carbon bonds interact with each other in a process called conjugation, which allows electrons in the molecule to move freely across these areas of the molecule. As the number of conjugated double bonds increases, electrons associated with conjugated systems have more room to move and this causes the range of energies of light absorbed by the molecule to decrease. As more frequencies of light are absorbed from the end of the visible spectrum. Carotenoids are usually due to the presence of long unsaturated aliphatic chains as in some fatty acids. The physiological absorption of these fat-soluble vitamins in humans and other organisms depends directly on the presence of fats, carotenoids are a common and often ornamental feature in animals. For example, the color of flamingos and salmon
11.
Algae
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Algae is an informal term for a large, diverse group of photosynthetic organisms which are not necessarily closely related, and is thus polyphyletic. Included organisms range from unicellular genera, such as Chlorella and the diatoms, to forms, such as the giant kelp. Most are aquatic and autotrophic and lack many of the cell and tissue types, such as stomata, xylem, and phloem. No definition of algae is generally accepted, one definition is that algae have chlorophyll as their primary photosynthetic pigment and lack a sterile covering of cells around their reproductive cells. Some authors exclude all prokaryotes thus do not consider cyanobacteria as algae, Algae constitute a polyphyletic group since they do not include a common ancestor, and although their plastids seem to have a single origin, from cyanobacteria, they were acquired in different ways. Green algae are examples of algae that have primary chloroplasts derived from endosymbiotic cyanobacteria, diatoms and brown algae are examples of algae with secondary chloroplasts derived from an endosymbiotic red alga. Algae exhibit a range of reproductive strategies, from simple asexual cell division to complex forms of sexual reproduction. Algae lack the various structures that characterize land plants, such as the phyllids of bryophytes, rhizoids in nonvascular plants, and the roots, leaves, and other organs found in tracheophytes. Most are phototrophic, although some are mixotrophic, deriving energy both from photosynthesis and uptake of organic carbon either by osmotrophy, myzotrophy, or phagotrophy. Some other heterotrophic organisms, such as the apicomplexans, are derived from cells whose ancestors possessed plastids. Fossilized filamentous algae from the Vindhya basin have been dated back to 1.6 to 1.7 billion years ago, the singular alga is the Latin word for seaweed and retains that meaning in English. Although some speculate that it is related to Latin algēre, be cold, a more likely source is alliga, binding, entwining. The Ancient Greek word for seaweed was φῦκος, which could mean either the seaweed or a red dye derived from it, the Latinization, fūcus, meant primarily the cosmetic rouge. It could be any color, black, red, green, accordingly, the modern study of marine and freshwater algae is called either phycology or algology, depending on whether the Greek or Latin root is used. The name Fucus appears in a number of taxa, most algae contain chloroplasts that are similar in structure to cyanobacteria. Chloroplasts contain circular DNA like that in cyanobacteria and presumably represent reduced endosymbiotic cyanobacteria, however, the exact origin of the chloroplasts is different among separate lineages of algae, reflecting their acquisition during different endosymbiotic events. The table below describes the composition of the three groups of algae. Their lineage relationships are shown in the figure in the upper right, many of these groups contain some members that are no longer photosynthetic
12.
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
. Retrieved 1 November 2014.
