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Polychaete Genera
Polychaeta () is a paraphyletic class of generally marine annelid worms, commonly called bristle worms or polychaetes (). Each body segment has a pair of fleshy protrusions called parapodia that bear many bristles, called chaetae, which are made of chitin. More than 10,000 species are described in this class. Common representatives include the lugworm (''Arenicola marina'') and the sandworm or clam worm ''Alitta''. Polychaetes as a class are robust and widespread, with species that live in the coldest ocean temperatures of the abyssal plain, to forms which tolerate the extremely high temperatures near hydrothermal vents. Polychaetes occur throughout the Earth's oceans at all depths, from forms that live as plankton near the surface, to a 2- to 3-cm specimen (still unclassified) observed by the robot ocean probe ''Nereus'' at the bottom of the Challenger Deep, the deepest known spot in the Earth's oceans. Only 168 species (less than 2% of all polychaetes) are known from fres ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cambrian
The Cambrian ( ) is the first geological period of the Paleozoic Era, and the Phanerozoic Eon. The Cambrian lasted 51.95 million years from the end of the preceding Ediacaran period 538.8 Ma (million years ago) to the beginning of the Ordovician Period 486.85 Ma. Most of the continents lay in the southern hemisphere surrounded by the vast Panthalassa Ocean. The assembly of Gondwana during the Ediacaran and early Cambrian led to the development of new convergent plate boundaries and continental-margin arc magmatism along its margins that helped drive up global temperatures. Laurentia lay across the equator, separated from Gondwana by the opening Iapetus Ocean. The Cambrian marked a profound change in life on Earth; prior to the Period, the majority of living organisms were small, unicellular and poorly preserved. Complex, multicellular organisms gradually became more common during the Ediacaran, but it was not until the Cambrian that fossil diversity seems to rapidly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lugworm
''Arenicola'', also known as sandworms, is a genus of capitellid annelid worms comprising the lugworms and black lugs. ''A.cristata'' is the dominant warm-water lugworm on the shores of North America and Humboldt Bay, California. ''A. caroledna'' dominates in China and Japan while ''Arenicola marina'' is mostly found in Europe, up to Norway. ''Arenicola loveni'' is restricted to Southern Africa. Species The following species are recognised in the genus ''Arenicola'': *'' Arenicola bombayensis'' Kewalramani et al * '' Arenicola brasiliensis'' Nonato, 1958 *'' Arenicola caroledna'' Wells * '' Arenicola cristata'' Stimpson, 1856 * '' Arenicola defodiens'' Cadman & Nelson-Smith, 1993 * '' Arenicola glasselli'' Berkeley & Berkeley, 1939 * '' Arenicola loveni'' Kinberg, 1866 * '' Arenicola marina'' (Linnaeus, 1758) Life in a burrow A lugworm lives in a U-shaped burrow in sand. The U is made of an L-shaped gallery lined with mucus, from the toe of which a vertical unlined shaft run ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ecological Niche
In ecology, a niche is the match of a species to a specific environmental condition. Three variants of ecological niche are described by It describes how an organism or population responds to the distribution of Resource (biology), resources and competitors (for example, by growing when resources are abundant, and when predators, parasites and pathogens are scarce) and how it in turn alters those same factors (for example, limiting access to resources by other organisms, acting as a food source for predators and a consumer of prey). "The type and number of variables comprising the dimensions of an environmental niche vary from one species to another [and] the relative importance of particular environmental variables for a species may vary according to the geographic and biotic contexts". See also Chapter 2: Concepts of niches, pp. 7 ''ff'' A Grinnellian niche is determined by the habitat in which a species lives and its accompanying Behavioral ecology, behavioral adaptations. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gas Exchange
Gas exchange is the physical process by which gases move passively by diffusion across a surface. For example, this surface might be the air/water interface of a water body, the surface of a gas bubble in a liquid, a gas-permeable membrane, or a biological membrane that forms the boundary between an organism and its extracellular environment. Gases are constantly consumed and produced by cellular and metabolic reactions in most living things, so an efficient system for gas exchange between, ultimately, the interior of the cell(s) and the external environment is required. Small, particularly unicellular organisms, such as bacteria and protozoa, have a high surface-area to volume ratio. In these creatures the gas exchange membrane is typically the cell membrane. Some small multicellular organisms, such as flatworms, are also able to perform sufficient gas exchange across the skin or cuticle that surrounds their bodies. However, in most larger organisms, which have small surface-a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Luminescent
Luminescence is a spontaneous emission of radiation from an electronically or vibrationally excited species not in thermal equilibrium with its environment. A luminescent object emits ''cold light'' in contrast to incandescence, where an object only emits light after heating. Generally, the emission of light is due to the movement of electrons between different energy levels within an atom after excitation by external factors. However, the exact mechanism of light emission in vibrationally excited species is unknown. The dials, hands, scales, and signs of aviation and navigational instruments and markings are often coated with luminescent materials in a process known as ''luminising''. Types * Ionoluminescence, a result of bombardment by fast ions * Radioluminescence, a result of bombardment by ionizing radiation * Electroluminescence, a result of an electric current passed through a substance ** Cathodoluminescence, a result of a luminescent material being struck by electro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Iridescent
Iridescence (also known as goniochromism) is the phenomenon of certain surfaces that appear gradually to change colour as the angle of view or the angle of illumination changes. Iridescence is caused by wave interference of light in microstructures or thin films. Examples of iridescence include soap bubbles, feathers, butterfly wings and seashell nacre, and minerals such as opal. Pearlescence is a related effect where some or most of the reflected light is white. The term pearlescent is used to describe certain paint finishes, usually in the automotive industry, which actually produce iridescent effects. Etymology The word ''iridescence'' is derived in part from the Greek word ἶρις ''îris'' ( gen. ἴριδος ''íridos''), meaning ''rainbow'', and is combined with the Latin suffix ''-escent'', meaning "having a tendency toward". Iris in turn derives from the goddess Iris of Greek mythology, who is the personification of the rainbow and acted as a messenger of the g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eunice Aphroditois
''Eunice aphroditois'' is a Benthic zone, benthic polychaete, bristle worm of warm marine waters. It lives mainly in the Atlantic Ocean, but can also be found in the Indo-Pacific. It ranges in length from less than to nearly . Its exoskeleton displays a wide range of colors, from black to purple and more. This species is an ambush predator; it hunts by burrowing its whole body in soft sediment on the ocean floor and waiting until its antennae detect prey. It then strikes with its sharp mandibles. It may also be found among coral reefs. ''Eunice aphroditois'' is also known as the bobbit worm or bobbitt worm. The name is believed to be taken from the John and Lorena Bobbitt case. It is sometimes called the sand striker or trap-jaw worm. Traces of their burrows have been found among fossils near Taiwan dating back twenty million years. Description These ambush predators have five antennae on their head that are used to sense prey. The body is covered by a hard exoskeleton. The ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrobiologia
''Hydrobiologia'', ''The International Journal of Aquatic Sciences'', is a peer-reviewed scientific journal publishing 21 issues per year, for a total of well over 4000 pages per year. ''Hydrobiologia'' publishes original research, reviews and opinions investigating the biology of freshwater and marine habitats, including the impact of human activities. Coverage includes molecular-, organism-, community -and ecosystem-level studies dealing with biological research in limnology and oceanography, including systematics and aquatic ecology. In addition to hypothesis-driven experimental research, it presents theoretical papers relevant to a broad hydrobiological audience, and collections of papers in special issues covering focused topics. History ''Hydrobiologia'' changed on the appointment of Henri Dumont to be its editor-in-chief. He introduced peer review, and expanded production from 6 issues per year to more than 20 per year. Koen Martens took over the responsibility as editor-i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Challenger Deep
The Challenger Deep is the List of submarine topographical features#List of oceanic trenches, deepest known point of the seabed of Earth, located in the western Pacific Ocean at the southern end of the Mariana Trench, in the ocean territory of the Federated States of Micronesia. The General Bathymetric Chart of the Oceans, GEBCO Gazetteer of Undersea Feature Names indicates that the feature is situated at and has an approximated maximum depth of below sea level. A subsequent study revised the value to at a 95% confidence interval. However, both the precise geographic location and depth remain ambiguous, with contemporary measurements ranging from . The depression is named after the British Royal Navy survey ships , whose Challenger expedition, expedition of 1872–1876 first located it, and HMS Challenger (1931), HMS ''Challenger II'', whose expedition of 1950–1952 established its record-setting depth. The first descent by any vehicle was conducted by the United States N ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nereus (underwater Vehicle)
''Nereus'' was a hybrid uncrewed autonomous underwater vehicle (HROV, a type of remotely operated underwater vehicle) built by the Woods Hole Oceanographic Institution (WHOI). Constructed as a research vehicle to operate at depths of up to , it was designed to explore Challenger Deep, the deepest surveyed point in the global ocean. ''Nereus'', named for Greek sea titan Nereus (who has a man's torso and a fish-tail) through a nationwide contest of high school and college students, began its deep sea voyage to Challenger Deep in May 2009 and reached the bottom on May 31, 2009. On this dive the ''Nereus'' reached a depth of , making the ''Nereus'' the world's deepest-diving vehicle in operation at the time, and the first since 1998 to explore the Mariana Trench, the deepest known part of the ocean. On 10 May 2014, ''Nereus'' was lost while exploring the Kermadec Trench at a depth of . Communications were cut off at around 2 p.m. local time, and debris retrieved later revealed that ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plankton
Plankton are the diverse collection of organisms that drift in Hydrosphere, water (or atmosphere, air) but are unable to actively propel themselves against ocean current, currents (or wind). The individual organisms constituting plankton are called plankters. In the ocean, they provide a crucial source of food to many small and large aquatic organisms, such as bivalves, fish, and baleen whales. Marine plankton include bacteria, archaea, algae, protozoa, microscopic fungi, and drifting or floating animals that inhabit the saltwater of oceans and the brackish waters of estuaries. fresh water, Freshwater plankton are similar to marine plankton, but are found in lakes and rivers. Mostly, plankton just drift where currents take them, though some, like jellyfish, swim slowly but not fast enough to generally overcome the influence of currents. Although plankton are usually thought of as inhabiting water, there are also airborne versions that live part of their lives drifting in the at ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrothermal Vent
Hydrothermal vents are fissures on the seabed from which geothermally heated water discharges. They are commonly found near volcanically active places, areas where tectonic plates are moving apart at mid-ocean ridges, ocean basins, and hotspots. The dispersal of hydrothermal fluids throughout the global ocean at active vent sites creates hydrothermal plumes. Hydrothermal deposits are rocks and mineral ore deposits formed by the action of hydrothermal vents. Hydrothermal vents exist because the Earth is both geologically active and has large amounts of water on its surface and within its crust. Under the sea, they may form features called black smokers or white smokers, which deliver a wide range of elements to the world's oceans, thus contributing to global marine biogeochemistry. Relative to the majority of the deep sea, the areas around hydrothermal vents are biologically more productive, often hosting complex communities fueled by the chemicals dissolved in the vent fl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
