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Sand Cay
A cay ( ), also spelled caye or key, is a small, low-elevation, sandy island on the surface of a coral reef. Cays occur in tropical environments throughout the Pacific, Atlantic, and Indian Oceans, including in the Caribbean and on the Great Barrier Reef and Belize Barrier Reef. Etymology The 1492 indigenous people of the Bahamas were called " Lucayan", an Anglicization of the Spanish ''Lucayos'', derived in turn from the Taíno ''Lukku-Cairi'' (which the people used for themselves), meaning "people of the islands". The Taíno word for "island", ''cairi'', became ''cayo'' in Spanish and "cay" in English (spelled "key" in American English, "caye" in Belizean English). Formation and composition A cay forms when ocean currents transport loose sediment across the surface of a reef to where the current slows or converges with another current, releasing its sediment load. Gradually, layers of deposited sediment build up on the reef surface – a '' depositional node''. Such n ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heron Island, Australia - View Of Island From Helicopter
The herons are long-legged, long-necked, freshwater and coastal birds in the family Ardeidae, with 72 recognised species, some of which are referred to as egrets or bitterns rather than herons. Members of the genera ''Botaurus'' and ''Ixobrychus'' are referred to as bitterns, and, together with the zigzag heron, or zigzag bittern, in the monotypic genus ''Zebrilus'', form a monophyletic group within the Ardeidae. Egrets do not form a biologically distinct group from herons, and tend to be named differently because they are mainly white or have decorative plumes in breeding plumage. Herons, by evolutionary adaptation, have long beaks. The classification of the individual heron/egret species is fraught with difficulty, and no clear consensus exists about the correct placement of many species into either of the two major genera, '' Ardea'' and '' Egretta''. Similarly, the relationships of the genera in the family are not completely resolved. However, one species formerly considere ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Deposition (geology)
Deposition is the geological process in which sediments, soil and rocks are added to a landform or landmass. Wind, ice, water, and gravity transport previously weathered surface material, which, at the loss of enough kinetic energy in the fluid, is deposited, building up layers of sediment. Deposition occurs when the forces responsible for sediment transportation are no longer sufficient to overcome the forces of gravity and friction, creating a resistance to motion; this is known as the null-point hypothesis. Deposition can also refer to the buildup of sediment from organically derived matter or chemical processes. For example, chalk is made up partly of the microscopic calcium carbonate skeletons of marine plankton, the deposition of which has induced chemical processes ( diagenesis) to deposit further calcium carbonate. Similarly, the formation of coal begins with the deposition of organic material, mainly from plants, in anaerobic conditions. Null-point hypothesis Th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silicate
In chemistry, a silicate is any member of a family of polyatomic anions consisting of silicon and oxygen, usually with the general formula , where . The family includes orthosilicate (), metasilicate (), and pyrosilicate (, ). The name is also used for any salt of such anions, such as sodium metasilicate; or any ester containing the corresponding chemical group, such as tetramethyl orthosilicate. The name "silicate" is sometimes extended to any anions containing silicon, even if they do not fit the general formula or contain other atoms besides oxygen; such as hexafluorosilicate .Most commonly, silicates are encountered as silicate minerals. For diverse manufacturing, technological, and artistic needs, silicates are versatile materials, both natural (such as granite, gravel, and garnet) and artificial (such as Portland cement, ceramics, glass, and waterglass). Structural principles In all silicates, silicon atom occupies the center of an idealized tetrahedron whose c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Foraminifera
Foraminifera (; Latin for "hole bearers"; informally called "forams") are single-celled organisms, members of a phylum or class of amoeboid protists characterized by streaming granular ectoplasm for catching food and other uses; and commonly an external shell (called a "test") of diverse forms and materials. Tests of chitin (found in some simple genera, and Textularia in particular) are believed to be the most primitive type. Most foraminifera are marine, the majority of which live on or within the seafloor sediment (i.e., are benthic), while a smaller number float in the water column at various depths (i.e., are planktonic), which belong to the suborder Globigerinina. Fewer are known from freshwater or brackish conditions, and some very few (nonaquatic) soil species have been identified through molecular analysis of small subunit ribosomal DNA. Foraminifera typically produce a test, or shell, which can have either one or multiple chambers, some becoming quite elaborate in s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mollusca
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant taxon, extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine biology, marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater mollusc, freshwater and Terrestrial molluscs, terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 Taxonomy (biology), taxonomic class (biology), classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurobiology, neurologically advanced of all inve ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secrete calcium carbonate to form a hard skeleton. A coral "group" is a colony of very many genetically identical polyps. Each polyp is a sac-like animal typically only a few millimeters in diameter and a few centimeters in height. A set of tentacles surround a central mouth opening. Each polyp excretes an exoskeleton near the base. Over many generations, the colony thus creates a skeleton characteristic of the species which can measure up to several meters in size. Individual colonies grow by asexual reproduction of polyps. Corals also breed sexually by spawning: polyps of the same species release gametes simultaneously overnight, often around a full moon. Fertilized eggs form planulae, a mobile early form of the coral polyp which, whe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Halimeda
''Halimeda'' is a genus of green macroalgae. The algal body (thallus) is composed of calcified green segments. Calcium carbonate is deposited in its tissues, making it inedible to most herbivores. However one species, ''Halimeda tuna'', was described as pleasant to eat with oil, vinegar, and salt. As in other members of the order Bryopsidales, individual organisms are made up of single multi-nucleate cells. Whole meadows may consist of a single individual alga connected by fine threads running through the substrate. ''Halimeda'' is responsible for distinctive circular deposits in various parts of the Great Barrier Reef on the north-east coast of Queensland, Australia. ''Halimeda'' beds form in the western or lee side of outer shield reefs where flow of nutrient-rich water from the open sea allows them to flourish, and are the most extensive, actively accumulating ''Halimeda'' beds in the world. The genus is one of the best studied examples of cryptic species pairs due to morpho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coralline Algae
Coralline algae are red algae in the order Corallinales. They are characterized by a thallus that is hard because of calcareous deposits contained within the cell walls. The colors of these algae are most typically pink, or some other shade of red, but some species can be purple, yellow, blue, white, or gray-green. Coralline algae play an important role in the ecology of coral reefs. Sea urchins, parrot fish, and limpets and chitons (both mollusks) feed on coralline algae. In the temperate Mediterranean Sea, coralline algae are the main builders of a typical algal reef, the ''Coralligène'' ("coralligenous"). Many are typically encrusting and rock-like, found in marine waters all over the world. Only one species lives in freshwater. Unattached specimens ( maerl, rhodoliths) may form relatively smooth compact balls to warty or fruticose thalli. A close look at almost any intertidal rocky shore or coral reef will reveal an abundance of pink to pinkish-grey patches, distributed th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcite
Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed mostly of calcite has numerous uses. Other polymorphs of calcium carbonate are the minerals aragonite and vaterite. Aragonite will change to calcite over timescales of days or less at temperatures exceeding 300 °C, and vaterite is even less stable. Etymology Calcite is derived from the German ''Calcit'', a term from the 19th century that came from the Latin word for lime, ''calx'' (genitive calcis) with the suffix "-ite" used to name minerals. It is thus etymologically related to chalk. When applied by archaeologists and stone trade professionals, the term alabaster is used not just as in geology and mineralogy, where it is res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aragonite
Aragonite is a carbonate mineral, one of the three most common naturally occurring crystal forms of calcium carbonate, (the other forms being the minerals calcite and vaterite). It is formed by biological and physical processes, including precipitation from marine and freshwater environments. The crystal lattice of aragonite differs from that of calcite, resulting in a different crystal shape, an orthorhombic crystal system with acicular crystal. Repeated twinning results in pseudo-hexagonal forms. Aragonite may be columnar or fibrous, occasionally in branching helictitic forms called ''flos-ferri'' ("flowers of iron") from their association with the ores at the Carinthian iron mines. Occurrence The type location for aragonite is Molina de Aragón in the Province of Guadalajara in Castilla-La Mancha, Spain, for which it was named in 1797. Aragonite is found in this locality as cyclic twins inside gypsum and marls of the Keuper facies of the Triassic. This type of ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motu (geography)
An islet is a very small, often unnamed island. Most definitions are not precise, but some suggest that an islet has little or no vegetation and cannot support human habitation. It may be made of rock, sand and/or hard coral; may be permanent or tidal (i.e. surfaced reef or seamount); and may exist in the sea, lakes, rivers or any other sizeable bodies of water. Definition As suggested by its origin ''islette'', an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability. The World Landforms website says, "An islet landform is generally considered to be a rock or small island that has little vegetation and cannot sustain human habitation", and further that size may vary from a few square feet to several square miles, with no specific rule pertaining to size. Other terms * Ait (/eɪt/, like eight) or eyot (/aɪ(ə)t, eɪt/), a small island. It is especially used to refer to river ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
