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Sessility (zoology)
Sessility is the biological property of an animal describing its lack of a means of self-locomotion. Sessile animals for which natural ''motility'' is absent are normally immobile. This is distinct from the botanical concept of sessility, which refers to an organism or biological structure attached directly by its base without a stalk. Sessile animals can move via external forces (such as water currents), but are usually permanently attached to something. Organisms such as corals lay down their own substrate from which they grow. Other organisms grow from a solid object, such as a rock, a dead tree trunk, or a human-made object such as a buoy or ship's hull. Mobility Sessile animals typically have a motile phase in their development. Sponges have a motile larval stage and become sessile at maturity. Conversely, many jellyfish develop as sessile polyps early in their life cycle. In the case of the cochineal, it is in the nymph stage (also called the crawler stage) that the c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydras (8)
''Hydra'' ( ) is a genus of small freshwater ecosystem, freshwater hydrozoans of the phylum Cnidaria. They are solitary, carnivorous jellyfish-like animals, native to the temperate climate, temperate and tropical climate, tropical regions. The genus was named by Linnaeus in 1758 after the Hydra (mythology), Hydra, which was the many-headed beast of myth defeated by Heracles, as when the animal has a part severed, it will regenerate much like the mythical hydra's heads. Biologists are especially interested in ''Hydra'' because of their regeneration (biology), regenerative ability; they do not appear to die of old age, or to senescence, age at all. Habitat Hydras are often found in freshwater bodies, but some hydras are found in open water. They live attached to submerged rocks using a sticky secretion from their base. Morphology ''Hydra'' has a tubular, symmetry (biology)#Radial symmetry, radially symmetric body up to long when extended, secured by a simple adhesive foot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tunicate
Tunicates are marine invertebrates belonging to the subphylum Tunicata ( ). This grouping is part of the Chordata, a phylum which includes all animals with dorsal nerve cords and notochords (including vertebrates). The subphylum was at one time called Urochordata, and the term urochordates is still sometimes used for these animals. Despite their simple appearance and very different adult form, their close relationship to the vertebrates is certain. Both groups are chordates, as evidenced by the fact that during their mobile larval stage, tunicates possess a notochord, a hollow dorsal nerve cord, pharyngeal slits, post-anal tail, and an endostyle. They resemble a tadpole. Tunicates are the only chordates that have lost their Myomere, myomeric segmentation, with the possible exception of the seriation of the gill slits. However, Doliolida, doliolids still display segmentation of the muscle bands. Some tunicates live as solitary individuals, but others replicate by budding and be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Peduncle (anatomy)
A peduncle is an elongated stalk of tissue. Sessility is the state of not having a peduncle; a sessile mass or structure lacks a stalk. In medicine, a mass such as a cyst or polyp is said to be ''pedunculated'' if it is supported by a peduncle. There are in total three types of peduncles in the cerebellum of the human brain, known as superior cerebellar peduncle, middle cerebellar peduncle, and inferior cerebellar peduncle. Pedunculated eyes are also the defining attribute of the stylophthalmine trait found in certain fish larvae. The caudal peduncle is a slightly narrowed part of a fish where the caudal fin meets the spine. See also * Peduncle (botany) References Gross pathology {{anatomy-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microorganism
A microorganism, or microbe, is an organism of microscopic scale, microscopic size, which may exist in its unicellular organism, single-celled form or as a Colony (biology)#Microbial colonies, colony of cells. The possible existence of unseen microbial life was suspected from antiquity, with an early attestation in Jain literature authored in 6th-century BC India. The scientific study of microorganisms began with their observation under the microscope in the 1670s by Anton van Leeuwenhoek. In the 1850s, Louis Pasteur found that microorganisms caused food spoilage, debunking the theory of spontaneous generation. In the 1880s, Robert Koch discovered that microorganisms caused the diseases tuberculosis, cholera, diphtheria, and anthrax. Microorganisms are extremely diverse, representing most unicellular organisms in all three domains of life: two of the three domains, Archaea and Bacteria, only contain microorganisms. The third domain, Eukaryota, includes all multicellular o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Carbonate Platform
A carbonate platform is a Sedimentary rock, sedimentary body which possesses topographic relief, and is composed of Autochthon (geology), autochthonic calcareous deposits. Platform growth is mediated by Sessility (zoology), sessile organisms whose skeletons build up the coral reef, reef or by organisms (usually microbes) which induce carbonate precipitation through their metabolism. Therefore, carbonate platforms can not grow up everywhere: they are not present in places where limiting factors to the life of reef-building organisms exist. Such limiting factors are, among others: light, water temperature, Transparency (optics), transparency and pH-Value. For example, carbonate sedimentation along the Atlantic South American coasts takes place everywhere but at the mouth of the Amazon River, because of the intense turbidity of the water there. Spectacular examples of present-day carbonate platforms are the Bahama Banks under which the platform is roughly 8 km thick, the Yucatan P ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oyster
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 highly calcified, and many are somewhat irregular in shape. Many, but not all oysters, are in the superfamily Ostreoidea. Some species of oyster are commonly consumed and are regarded as a delicacy in some localities. Some types of pearl oysters are harvested for the pearl produced within the mantle. Others, such as the translucent Windowpane oysters, are harvested for their shells. Etymology The word ''oyster'' comes from Old French , and first appeared in English during the 14th century. The French derived from the Latin , the feminine form of , which is the Latinisation (literature), latinisation of the Ancient Greek () 'oyster'. Compare () 'bone'. Types True oysters True oysters are members of the family Ostreidae. This family includes the edible oysters, which mainly belong to the genera '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biome
A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. In 1935, Tansley added the climatic and soil aspects to the idea, calling it ''ecosystem''. The International Biological Program (1964–74) projects popularized the concept of biome. However, in some contexts, the term ''biome'' is used in a different manner. In German literature, particularly in the Walter terminology, the term is used similarly as '' biotope'' (a concrete geographical unit), while the biome definition used in this article is used as an international, non-regional, terminology—irrespectively of the continent in which an area is present, it takes the same biome name—and corresponds to his "zonobiome", "orobiome" and "pedobiome" (biomes determined by climate zone, altitude or soil). In the Brazilian literature, the term ''biome'' is sometimes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coast
A coast (coastline, shoreline, seashore) is the land next to the sea or the line that forms the boundary between the land and the ocean or a lake. Coasts are influenced by the topography of the surrounding landscape and by aquatic erosion, such as that caused by wind wave, waves. The geology, geological composition of rock (geology), rock and soil dictates the type of shore that is created. Earth has about of coastline. Coasts are important zones in natural ecosystems, often home to a wide range of biodiversity. On land, they harbor ecosystems, such as freshwater marsh, freshwater or estuary, estuarine wetlands, that are important for birds and other terrestrial animals. In wave-protected areas, coasts harbor salt marshes, mangroves, and seagrass meadow, seagrasses, all of which can provide nursery habitat for finfish, shellfish, and other aquatic animals. Rocky shores are usually found along exposed coasts and provide habitat for a wide range of sessility (motility), sessile ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Littoral Zone
The littoral zone, also called litoral or nearshore, is the part of a sea, lake, or river that is close to the shore. In coastal ecology, the littoral zone includes the intertidal zone extending from the high water mark (which is rarely flood, inundated), to coastal areas that are permanently underwater, submerged — known as the ''foreshore'' — and the terms are often used interchangeably. However, the geographical meaning of ''littoral zone'' extends well beyond the intertidal zone to include all neritic waters within the bounds of continental shelves. Etymology The word ''littoral'' may be used both as a noun and as an adjective. It derives from the Latin language, Latin noun ''litus, litoris'', meaning "shore". (The doubled ''t'' is a late-medieval innovation, and the word is sometimes seen in the more classical-looking spelling ''litoral''.) Description The term has no single definition. What is regarded as the full extent of the littoral zone, and the way the littora ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Academic Press
Academic Press (AP) is an academic book publisher founded in 1941. It launched a British division in the 1950s. Academic Press was acquired by Harcourt, Brace & World in 1969. Reed Elsevier said in 2000 it would buy Harcourt, a deal completed the next year, after a regulatory review. Thus, Academic Press is now an imprint of Elsevier. Academic Press publishes reference books, serials and online products in the subject areas of: * Communications engineering * Economics * Environmental science * Finance * Food science and nutrition * Geophysics * Life sciences * Mathematics and statistics * Neuroscience * Physical sciences * Psychology Psychology is the scientific study of mind and behavior. Its subject matter includes the behavior of humans and nonhumans, both consciousness, conscious and Unconscious mind, unconscious phenomena, and mental processes such as thoughts, feel ... Well-known products include the '' Methods in Enzymology'' series and encyclopedias such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coral Reef
A coral reef is an underwater ecosystem characterized by reef-building corals. Reefs are formed of colonies of coral polyps held together by calcium carbonate. Most coral reefs are built from stony corals, whose polyps cluster in groups. Coral belongs to the class Anthozoa in the animal phylum Cnidaria, which includes sea anemones and jellyfish. Unlike sea anemones, corals secrete hard carbonate exoskeletons that support and protect the coral. Most reefs grow best in warm, shallow, clear, sunny and agitated water. Coral reefs first appeared 485 million years ago, at the dawn of the Early Ordovician, displacing the microbial and sponge reefs of the Cambrian. Sometimes called ''rainforests of the sea'', shallow coral reefs form some of Earth's most diverse ecosystems. They occupy less than 0.1% of the world's ocean area, about half the area of France, yet they provide a home for at least 25% of all marine species, including fish, mollusks, worms, crustaceans, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Blue Mussel Clump
Blue is one of the three primary colours in the RYB colour model (traditional colour theory), as well as in the RGB (additive) colour model. It lies between violet and cyan on the spectrum of visible light. The term ''blue'' generally describes colours perceived by humans observing light with a dominant wavelength that's between approximately 450 and 495 nanometres. Most blues contain a slight mixture of other colours; azure contains some green, while ultramarine contains some violet. The clear daytime sky and the deep sea appear blue because of an optical effect known as Rayleigh scattering. An optical effect called the Tyndall effect explains blue eyes. Distant objects appear more blue because of another optical effect called aerial perspective. Blue has been an important colour in art and decoration since ancient times. The semi-precious stone lapis lazuli was used in ancient Egypt for jewellery and ornament and later, in the Renaissance, to make the pigment ultr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
