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Pelagic Sediments
Pelagic sediment or pelagite is a fine-grained sediment that accumulates as the result of the settling of particles to the floor of the open ocean, far from land. These particles consist primarily of either the microscopic, calcareous or siliceous shells of phytoplankton or zooplankton; clay-size siliciclastic sediment; or some mixture of these, along with detritus ( marine snow) included. Trace amounts of meteoric dust and variable amounts of volcanic ash also occur within pelagic sediments. Based upon the composition of the ooze, there are three main types of pelagic sediments: siliceous oozes, calcareous oozes, and red clays.Rothwell, R.G., (2005) ''Deep Ocean Pelagic Oozes'', Vol. 5. of Selley, Richard C., L. Robin McCocks, and Ian R. Plimer, Encyclopedia of Geology, Oxford: Elsevier Limited. HüNeke, H., and T. Mulder (2011) ''Deep-Sea Sediments''. Developments in Sedimentology, vol. 63. Elsiever, New York. 849 pp. The composition of pelagic sediments is controlled ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tripod Fish
Tripod fish is a common name for different species of fish: *Ipnopidae, a family found worldwide in deep seas, including: **''Bathypterois grallator The tripod fish or tripod spiderfish, ''Bathypterois grallator'', is a deep-sea benthic fish in the family Ipnopidae found at lower latitudes. It is now an iconic deep-sea fish, being observed and photographed by submersibles, using elongate ...'', the most famous species in the family * Triacanthidae, a family from the Indo-Pacific {{Disambiguation, fish ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sand
Sand is a granular material composed of finely divided mineral particles. Sand has various compositions but is usually defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass. The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz. Calcium carbonate is the second most common type of sand. One such example of this is aragonite, which has been created over the past 500million years by various forms of life, such as coral and shellfish. It is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years, as in the Caribbean. Somewhat more rarely, sand may be composed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dictyochales
The silicoflagellates (order Dictyochales) are a small group of unicellular photosynthetic protists, or algae, belonging to the supergroup of eukaryotes known as Stramenopiles. They behave as plankton and are present in oceanic waters. They are well-known from harmful algal blooms that cause high mortality of fish. Additionally, they compose a rich fossil record represented by their silica skeletons. Morphology The silicoflagellates are unicellular protists, composed of cells with one emergent flagellum and a siliceous skeleton constructed from a network of hollow rods outside of the cytoplasm. The morphology of the skeleton can vary greatly, from a simple ring, an ellipse or triangle, to a more complex and complete arrangement of rods. For example, in '' Dictyocha fibula'' (pictured) the skeleton rods are arranged in a series of peripheral polygons surrounding a central hexagon. These skeletons form a small component of marine sediments, and are well-known microfossils ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spicule (sponge)
Spicules are structural elements found in most Sea sponge, sponges. The meshing of many spicules serves as the sponge's skeleton and thus it provides structural support and potentially defense against predators. Sponge spicules are made of calcium carbonate or Silicon dioxide, silica. Large spicules visible to the naked eye are referred to as megascleres or macroscleres, while smaller, microscopic ones are termed microscleres. The composition, size, and shape of spicules are major characters in sponge systematics and Taxonomy (biology), taxonomy. Overview Sponges are a species-rich clade of the earliest-diverging (most Basal (phylogenetics), basal) animals. They are distributed globally, with diverse ecologies and functions, and a record spanning at least the entire Phanerozoic. Most sponges produce skeletons formed by spicules, structural elements that develop in a wide variety of sizes and three dimensional shapes. Among the four sub-clades of Porifera, three (Demospong ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sponge
Sponges or sea sponges are primarily marine invertebrates of the animal phylum Porifera (; meaning 'pore bearer'), a basal clade and a sister taxon of the diploblasts. They are sessile filter feeders that are bound to the seabed, and are one of the most ancient members of macrobenthos, with many historical species being important reef-building organisms. Sponges are multicellular organisms consisting of jelly-like mesohyl sandwiched between two thin layers of cells, and usually have tube-like bodies full of pores and channels that allow water to circulate through them. They have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. They do not have complex nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes, usually via flagella movements of the so-called " collar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siliceous Ooze
Siliceous ooze is a type of biogenic pelagic sediment located on the Abyssal, deep ocean floor. Siliceous oozes are the least common of the deep sea sediments, and make up approximately 15% of the ocean floor. Oozes are defined as sediments which contain at least 30% skeletal remains of pelagic microorganisms. Siliceous oozes are largely composed of the silica based skeletons of microscopic marine organisms such as diatoms and radiolarians. Other components of siliceous oozes near continental margins may include terrestrially derived silica particles and sponge spicules. Siliceous oozes are composed of skeletons made from opal silica SiO2, SiO2·''n''H2O, as opposed to calcareous oozes, which are made from skeletons of calcium carbonate (CaCO3, CaCO3SiO2, ·''n''H2O) organisms (i.e. coccolithophores). Silicon (Si) is a bioessential element and is efficiently recycled in the marine environment through the silica cycle. Distance from land masses, water depth and ocean fertility are al ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonate Compensation Depth
The carbonate compensation depth (CCD) is the depth, in the oceans, at which the rate of supply of calcium carbonates matches the rate of solvation. That is, solvation 'compensates' supply. Below the CCD solvation is faster, so that carbonate particles dissolve and the carbonate shells ( Test (biology) , tests) of animals are not preserved. Carbonate particles cannot accumulate in the sediments where the sea floor is below this depth. Calcite is the least soluble of these carbonates, so the CCD is normally the compensation depth for calcite. The aragonite compensation depth (ACD) is the compensation depth for aragonite, aragonitic carbonates. Aragonite is more soluble than calcite, and the aragonite compensation depth is generally shallower than both the calcite compensation depth and the CCD. Overview As shown in the diagram, biogenic calcium carbonate (CaCO3) Test (biology), tests are produced in the photic zone of the oceans (green circles). Upon death, those tests esca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcareous Ooze
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adjectival term applied to anatomical structures which are made primarily of calcium carbonate, in animals such as gastropods, i.e., snails, specifically in relation to such structures as the operculum, the clausilium, and the love dart. The term also applies to the calcium carbonate tests of, often, more-or-less microscopic Foraminifera. Not all tests are calcareous; diatoms and radiolaria have siliceous tests. The molluscs are calcareous organisms, as are the calcareous sponges ( Calcarea), that have spicules which are made of calcium carbonate. Additionally, reef-building corals, or Scleractinia, are calcareous organisms that form their rigid skeletal structure through the precipitation of aragonite (''i.e.'', a polymorph of calci ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Millennium
A millennium () is a period of one thousand years, one hundred decades, or ten centuries, sometimes called a kiloannum (ka), or kiloyear (ky). Normally, the word is used specifically for periods of a thousand years that begin at the starting point (initial reference point) of the calendar in consideration and at later years that are whole number multiples of a thousand years after the start point. The term can also refer to an interval of time beginning on any date. Millennia sometimes have religious or theological implications (see millenarianism). The word ''millennium'' derives from the Latin ', ''thousand'', and ', year. Debate over millennium celebrations There was a public debate leading up to the celebrations of the year 2000 as to whether the beginning of that year should be understood as the beginning of the "new" millennium. Historically, there has been debate around the turn of previous decades, centuries, and millennia, but not so much for decades. The issue ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radiolarian
The Radiolaria, also called Radiozoa, are unicellular eukaryotes of diameter 0.1–0.2 mm that produce intricate mineral skeletons, typically with a central capsule dividing the cell into the inner and outer portions of endoplasm and ectoplasm. The elaborate mineral skeleton is usually made of silica. They are found as zooplankton throughout the global ocean. As zooplankton, radiolarians are primarily heterotrophic, but many have photosynthetic endosymbionts and are, therefore, considered mixotrophs. The skeletal remains of some types of radiolarians make up a large part of the cover of the ocean floor as siliceous ooze. Due to their rapid change as species and intricate skeletons, radiolarians represent an important diagnostic fossil found from the Cambrian onwards. Description Radiolarians have many needle-like pseudopods supported by bundles of microtubules, which aid in the radiolarian's buoyancy. The cell nucleus and most other organelles are in the endoplasm, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Globigerina
''Globigerina'' () is a genus of planktonic Foraminifera, in the order of Rotaliida.Globigerina World Foraminifera Database, accessed 3 December 2018 It has populated the world's oceans since the Middle Jurassic. ''Globigerina'' ooze Vast areas of the ocean floor are covered with ''Globigerina'' Pelagic sediments, ooze, dominated by the foraminiferous shells of ''Globigerina'' and other Globigerinina. The name was originally applied to mud collected from the bottom of the Atlantic Ocean when planning the location of the first transatlantic telegraph cables and it was mainly composed of the shells of ''Globigerina bulloides''.Description ''Globigerina'' is a marine microorganism characterized by its spherical, coiled shell known as a test (biology), test. The t ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
