The Ostreidae, the true oysters, include most species of molluscs consumed as oysters. Pearl oysters are not true oysters, belong to the order Pterioida. Like scallops, true oysters have a central adductor muscle, which means the shell has a characteristic central scar marking its point of attachment; the shell tends to be irregular as a result of attaching to a substrate. Both oviparous and larviparous species are known within Ostreidae. Both types are hermaphrodites. However, the larviparous species show a pattern of alternating sex within each individual, whereas the oviparous species are simultaneous hermaphrodites, producing either female or male gametes according to circumstances. Members of genus Ostrea live continually immersed and are quite flat, with roundish shells, they differ from most bivalves by having shells made up of calcite, but with internal muscle scars of aragonitic composition. They fare best in somewhat oligotrophic water, they brood their fertilized eggs for various proportions of the period from fertilization to hatching.
Members of genera Saccostrea and Crassostrea live in the intertidal zone, broadcast sperm and eggs into the sea, can thrive in eutrophic water. One of the most cultivated oysters is the Pacific oyster, ideally suited for cultivation in seawater ponds. Alectryonella Agerostrea Vialov 1936 Anomiostrea Booneostrea Crassostrea Sacco 1897 Magallana Salvi & Mariottini 2016Magallana angulata M. ariakensis M. belcheri M. bilineata M. dactylena M. gigas M. hongkongensis M. nippona M. revularis M. sikamea Cryptostrea Harry 1985 (synonymous with OstreaC. Permollis G. B. Sowerby II 1871 - sponge oyster Dendostrea Swainson 1835 D. frons L. 1758 - frond oyster Lopha Röding 1798 L. cristagalli L. cockscomb oyster L. frons L. 1758 Nanostrea Ostrea L. 1758 Planostrea Pretostrea Pustulostrea Saccostrea Striostrea S. margariacea Lamarck 1819 - sand oyster S. denticulata Born 1778 S. prismatica Gray 1825 Teskeyostrea Harry 1985 T. weberi Olsson 1951 - threaded oyster, Weber oyster
Ostrea is a genus of edible oysters, marine bivalve mollusks in the family Ostreidae, the oysters. This genus is ancient, it is known in the fossil records from the Permian to the Quaternary. Fossil shells of these molluscs can be found all over the world. Genus Ostrea includes about 150 extinct species. At least one species within this genus, Ostrea lurida, has been recovered in archaeological excavations along the Central California coast of the Pacific Ocean, demonstrating it was a marine taxon exploited by the Native American Chumash people as a food source. Species in the genus Ostrea include: Shellfish James Dwight Dana Manual of Geology: Treating of the Principles of the Science with Special Reference to American Geological History, American Book Co. 1088 pages C. Michael Hogan Morro Creek, The Megalithic Portal, ed. by A. Burnham
Oyster is the common name for a number of different families of salt-water bivalve molluscs that live in marine or brackish habitats. In some species the valves are calcified, many are somewhat irregular in shape. Many, but not all, oysters are in the superfamily Ostreoidea; some kinds of oysters are consumed cooked or raw and are regarded as a delicacy. Some kinds of pearl oysters are harvested for the pearl produced within the mantle. Windowpane oysters are harvested for their translucent shells, which are used to make various kinds of decorative objects. First attested in English during the 14th century, the word "oyster" comes from Old French oistre, in turn from Latin ostrea, the feminine form of ostreum, the latinisation of the Greek ὄστρεον, "oyster". Compare ὀστέον, "bone". True oysters are members of the family Ostreidae; this family includes the edible oysters, which belong to the genera Ostrea, Ostreola and Saccostrea. Examples include the Belon oyster, eastern oyster, Olympia oyster, Pacific oyster, the Sydney rock oyster.
All shell-bearing mollusks can secrete pearls, yet most are not valuable. Pearls can form in both freshwater environments. Pearl oysters are not related to true oysters, being members of a distinct family, the feathered oysters. Both cultured pearls and natural pearls can be extracted from pearl oysters, though other molluscs, such as the freshwater mussels yield pearls of commercial value; the largest pearl-bearing oyster is the marine Pinctada maxima, the size of a dinner plate. Not all individual oysters produce pearls naturally. In fact, in a harvest of two and a half tons of oysters, only three to four oysters produce what commercial buyers consider to be absolute perfect pearls. In nature, pearl oysters produce pearls by covering a minute invasive object with nacre. Over the years, the irritating object is covered with enough layers of nacre to become a pearl; the many different types and shapes of pearls depend on the natural pigment of the nacre, the shape of the original irritant. Pearl farmers can culture a pearl by placing a nucleus a piece of polished mussel shell, inside the oyster.
In three to seven years, the oyster can produce a perfect pearl. These pearls are not as valuable as natural pearls, but look the same. In fact, since the beginning of the 20th century, when several researchers discovered how to produce artificial pearls, the cultured pearl market has far outgrown the natural pearl market. A number of bivalve molluscs have common names that include the word "oyster" because they either taste like or look somewhat like true oysters, or because they yield noticeable pearls. Examples include: Thorny oysters in the genus Spondylus Pilgrim oyster, another term for a scallop, in reference to the scallop shell of St. James Saddle oysters, members of the Anomiidae family known as jingle shells Dimydarian oysters, members of the family Dimyidae Windowpane oysters In the Philippines, a local thorny oyster species known as Tikod Amo is a favorite seafood source in the southern part of the country; because of its good flavor, it commands high prices. Oysters are filter feeders.
Suspended plankton and particles are trapped in the mucus of a gill, from there are transported to the mouth, where they are eaten and expelled as feces or pseudofeces. Oysters feed most at temperatures above 10 °C. An oyster can filter up to 5 L of water per hour; the Chesapeake Bay's once-flourishing oyster population filtered excess nutrients from the estuary's entire water volume every three to four days. Today, that would take nearly a year. Excess sediment and algae can result in the eutrophication of a body of water. Oyster filtration can mitigate these pollutants. In addition to their gills, oysters can exchange gases across their mantles, which are lined with many small, thin-walled blood vessels. A small, three-chambered heart, lying under the adductor muscle, pumps colorless blood to all parts of the body. At the same time, two kidneys, located on the underside of the muscle, remove waste products from the blood, their nervous system includes three pairs of ganglia. While some oysters have two sexes, their reproductive organs contain sperm.
Because of this, it is technically possible for an oyster to fertilize its own eggs. The gonads surround the digestive organs, are made up of sex cells, branching tubules, connective tissue. Once the female is fertilized, she discharges millions of eggs into the water; the larvae develop in about six hours and exist suspended in the water column as veliger larvae for two to three weeks before settling on a bed and maturing to sexual adulthood within a year. A group of oysters is called a bed or oyster reef; as a keystone species, oysters provide habitat for many marine species. Crassostrea and Saccostrea live in the intertidal zone, while Ostrea is subtidal; the hard surfaces of oyster shells and the nooks between the shells provide places where a host of small animals can live. Hundreds of animals, such as sea anemones and hooked mussels, inhabit oyster reefs. Many of these animals are prey to larger animals, including fish, such as striped bass, black drum and croakers. An oyster reef can increase the surface area of a flat bottom 50-fold.
An oyster's mature shape depends on the type of bottom to which it is attached, but it always orients itself with its outer, flared shell tilted upward. One valve is cupped and t
Fossilworks is a portal which provides query and analysis tools to facilitate access to the Paleobiology Database, a large relational database assembled by hundreds of paleontologists from around the world. Fossilworks is housed at Macquarie University, it includes many analysis and data visualization tools included in the Paleobiology Database. "Fossilworks". Retrieved 2010-04-08
A fungus is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separate from the other eukaryotic life kingdoms of plants and animals. A characteristic that places fungi in a different kingdom from plants and some protists is chitin in their cell walls. Similar to animals, fungi are heterotrophs. Fungi do not photosynthesize. Growth is their means of mobility, except for spores, which may travel through the water. Fungi are the principal decomposers in ecological systems; these and other differences place fungi in a single group of related organisms, named the Eumycota, which share a common ancestor, an interpretation, strongly supported by molecular phylogenetics. This fungal group oomycetes; the discipline of biology devoted to the study of fungi is known as mycology. In the past, mycology was regarded as a branch of botany, although it is now known fungi are genetically more related to animals than to plants.
Abundant worldwide, most fungi are inconspicuous because of the small size of their structures, their cryptic lifestyles in soil or on dead matter. Fungi include symbionts of plants, animals, or other fungi and parasites, they may become noticeable when fruiting, either as molds. Fungi perform an essential role in the decomposition of organic matter and have fundamental roles in nutrient cycling and exchange in the environment, they have long been used in the form of mushrooms and truffles. Since the 1940s, fungi have been used for the production of antibiotics, more various enzymes produced by fungi are used industrially and in detergents. Fungi are used as biological pesticides to control weeds, plant diseases and insect pests. Many species produce bioactive compounds called mycotoxins, such as alkaloids and polyketides, that are toxic to animals including humans; the fruiting structures of a few species contain psychotropic compounds and are consumed recreationally or in traditional spiritual ceremonies.
Fungi can break down manufactured materials and buildings, become significant pathogens of humans and other animals. Losses of crops due to fungal diseases or food spoilage can have a large impact on human food supplies and local economies; the fungus kingdom encompasses an enormous diversity of taxa with varied ecologies, life cycle strategies, morphologies ranging from unicellular aquatic chytrids to large mushrooms. However, little is known of the true biodiversity of Kingdom Fungi, estimated at 2.2 million to 3.8 million species. Of these, only about 120,000 have been described, with over 8,000 species known to be detrimental to plants and at least 300 that can be pathogenic to humans. Since the pioneering 18th and 19th century taxonomical works of Carl Linnaeus, Christian Hendrik Persoon, Elias Magnus Fries, fungi have been classified according to their morphology or physiology. Advances in molecular genetics have opened the way for DNA analysis to be incorporated into taxonomy, which has sometimes challenged the historical groupings based on morphology and other traits.
Phylogenetic studies published in the last decade have helped reshape the classification within Kingdom Fungi, divided into one subkingdom, seven phyla, ten subphyla. The English word fungus is directly adopted from the Latin fungus, used in the writings of Horace and Pliny; this in turn is derived from the Greek word sphongos, which refers to the macroscopic structures and morphology of mushrooms and molds. The word mycology is derived from the Greek logos, it denotes the scientific study of fungi. The Latin adjectival form of "mycology" appeared as early as 1796 in a book on the subject by Christiaan Hendrik Persoon; the word appeared in English as early as 1824 in a book by Robert Kaye Greville. In 1836 the English naturalist Miles Joseph Berkeley's publication The English Flora of Sir James Edward Smith, Vol. 5. Refers to mycology as the study of fungi. A group of all the fungi present in a particular area or geographic region is known as mycobiota, e.g. "the mycobiota of Ireland". Before the introduction of molecular methods for phylogenetic analysis, taxonomists considered fungi to be members of the plant kingdom because of similarities in lifestyle: both fungi and plants are immobile, have similarities in general morphology and growth habitat.
Like plants, fungi grow in soil and, in the case of mushrooms, form conspicuous fruit bodies, which sometimes resemble plants such as mosses. The fungi are now considered a separate kingdom, distinct from both plants and animals, from which they appear to have diverged around one billion years ago; some morphological and genetic features are shared with other organisms, while others are unique to the fungi separating them from the other kingdoms: Shared features: With other euka
The Pleosporales is the largest order in the fungal class Dothideomycetes. By a 2008 estimate it contains 332 genera and more than 4700 species; the majority of species are saprobes on decaying plant material in fresh water, marine, or terrestrial environments, but several species are associated with living plants as parasites, epiphytes or endophytes. The best studied species cause plant diseases on important agricultural crops e.g. Cochliobolus heterostrophus, causing southern corn leaf blight on maize, Phaeosphaeria nodorum causing glume blotch on wheat and Leptosphaeria maculans causing a stem canker on cabbage crops; some species of Pleosporales occur on animal dung and a small number occur as lichens and rock-inhabiting fungi. The order was proposed in 1955 as Dothideomycetes with perithecioid ascomata with pseudoparaphyses amongst the asci, at which time there were seven families. Three further families were added in 1973; the order was only formally described in 1987 with 21 families.
Five families were added in 2009. The family Halojulellaceae was circumscribed in 2013. Margaret E. Barr accepted six suborders within which to arrange the families. A suborder, Pleosporineae has been proposed, including four families. Massarineae with five families; the Pleosporales form. As a result of phylogenetic studies, the Pleosporales have undergone considerable reorganisation with reference to the large genus Phoma and the family Didymellaceae. A number of genera considered incertae sedis have now been placed within the latter family; these are genera of the Pleosporales of uncertain taxonomy. The oldest member of Pleosporales is the extinct genus Margaretbarromyces, described from Eocene age strata on Vancouver Island, British Columbia. Zhang Y, Crous PW, Schoch CL, Hyde KD.. "Pleosporales". Fungal Diversity. 53: 1–221. Doi:10.1007/s13225-011-0117-x. PMC 3477819. PMID 23097638. CS1 maint: Uses authors parameter Schoch CL, Crous PW, Groenewald JZS, Boehm EWA, BurgessTI, Gruyter J De, Hoog GS De, Dixon LJ,Grube M, Gueidan C, Harada Y, Hatakeyama S, Hirayama K, Hosoya T, Huhndorf SM, Hyde KD, Jones EBG, Kohlmeyer J, Kruys Å, Li YM, Lücking R, Lumbsch HT, Marvanová L, Mbatchou JS, McVay AH, Miller AN, Mugambi GK, Muggia L, Nelsen MP, Nelson P, Owensby CA, Phillips AJL, Phongpaichit S, Pointing SB, Pujade-Renaud V, Raja HA, Rivas Plata E, Robbertse B, Ruibal C, Sakayaroj J, Sano T, Selbmann L, Shearer CA, Shirouzu T, Slippers B, Suetrong S, Tanaka K, Volkmann-Kohlmeyer B, Wingfield MJ, Wood AR, Woudenberg JHC, Yonezawa H, Zhang Y, Spatafora JW..
"A class-wide phylogenetic assessment of Dothideomycetes". Studies in Mycology. 64: 1–15. Doi:10.3114/sim.2009.64.01. PMC 2816964. PMID 20169021. Retrieved 2010-02-04. CS1 maint: Uses authors parameter
Ascomycota is a division or phylum of the kingdom Fungi that, together with the Basidiomycota, form the subkingdom Dikarya. Its members are known as the sac fungi or ascomycetes, it is the largest phylum of Fungi, with over 64,000 species. The defining feature of this fungal group is the "ascus", a microscopic sexual structure in which nonmotile spores, called ascospores, are formed. However, some species of the Ascomycota are asexual, meaning that they do not have a sexual cycle and thus do not form asci or ascospores. Familiar examples of sac fungi include morels, brewer's yeast and baker's yeast, dead man's fingers, cup fungi; the fungal symbionts in the majority of lichens such as Cladonia belong to the Ascomycota. Ascomycota is a monophyletic group. Placed in the Deuteromycota along with asexual species from other fungal taxa, asexual ascomycetes are now identified and classified based on morphological or physiological similarities to ascus-bearing taxa, by phylogenetic analyses of DNA sequences.
The ascomycetes are of particular use to humans as sources of medicinally important compounds, such as antibiotics, for fermenting bread, alcoholic beverages and cheese. Penicillium species on cheeses and those producing antibiotics for treating bacterial infectious diseases are examples of ascomycetes. Many ascomycetes are pathogens, both of animals, including humans, of plants. Examples of ascomycetes that can cause infections in humans include Candida albicans, Aspergillus niger and several tens of species that cause skin infections; the many plant-pathogenic ascomycetes include apple scab, rice blast, the ergot fungi, black knot, the powdery mildews. Several species of ascomycetes are biological model organisms in laboratory research. Most famously, Neurospora crassa, several species of yeasts, Aspergillus species are used in many genetics and cell biology studies. Ascomycetes: Ascomycetes are'spore shooters', they are fungi which produce microscopic spores inside special, elongated cells or sacs, known as'asci', which give the group its name.
Asexual reproduction: Asexual reproduction is the dominant form of propagation in the Ascomycota, is responsible for the rapid spread of these fungi into new areas. Asexual reproduction of ascomycetes is diverse from both structural and functional points of view; the most important and general is production of conidia, but chlamydospores are frequently produced. Furthermore, Ascomycota reproduce asexually through budding. 1) Conidia formation: Asexual reproduction may occur through vegetative reproductive spores, the conidia. The asexual, non-motile haploid spores of a fungus, which are named after the Greek word for dust, are hence known as conidiospores and mitospores; the conidiospores contain one nucleus and are products of mitotic cell divisions and thus are sometimes call mitospores, which are genetically identical to the mycelium from which they originate. They are formed at the ends of specialized hyphae, the conidiophores. Depending on the species they may be dispersed by animals. Conidiophores may branch off from the mycelia or they may be formed in fruiting bodies.
The hypha that creates the sporing tip can be similar to the normal hyphal tip, or it can be differentiated. The most common differentiation is the formation of a bottle shaped cell called a phialide, from which the spores are produced. Not all of these asexual structures are a single hypha. In some groups, the conidiophores are aggregated to form a thick structure. E.g. In the order Moniliales, all of them are single hyphae with the exception of the aggregations, termed as coremia or synnema; these produce structures rather like corn-stokes, with many conidia being produced in a mass from the aggregated conidiophores. The diverse conidia and conidiophores sometimes develop in asexual sporocarps with different characteristics; some species of Ascomycetes form their structures within plant tissue, either as parasite or saprophytes. These fungi have evolved more complex asexual sporing structures influenced by the cultural conditions of plant tissue as a substrate; these structures are called the sporodochium.
This is a cushion of conidiophores created from a pseudoparenchymatous stroma in plant tissue. The pycnidium is a globose to flask-shaped parenchymatous structure, lined on its inner wall with conidiophores; the acervulus is a flat saucer shaped bed of conidiophores produced under a plant cuticle, which erupt through the cuticle for dispersal. 2) Budding: Asexual reproduction process in ascomycetes involves the budding which we observe in yeast. This is termed a “blastic process”, it involves the blebbing of the hyphal tip wall. The blastic process can involve all wall layers, or there can be a new cell wall synthesized, extruded from within the old wall; the initial events of budding can be seen as the development of a ring of chitin around the point where the bud is about to appear. This stabilizes the cell wall. Enzymatic activity and turgor pressure act to extrude the cell wall. New cell wall material is incorporated during this phase. Cell contents are forced into the progeny cell, as the final phase of mitosis ends a cell plate, the point at which a new cell wall will grow inwards from, forms.
Ascomycota are morphologically diverse. The group includes organisms from unicellular yeasts to complex cup fungi. There are 30,000 species of Ascomycota; the unifying characteri