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Pennate Diatom
The order Pennales is a traditional subdivision of the heterokont algae known as diatoms. The order is named for the shape of the cell walls (or valves or frustules) of pennate diatoms, which are elongated in valve view. The valves may be linear or oval in shape, and usually bear bilaterally symmetrical ornamental patterns. These patterns are composed of a series of transverse lines (known as striae) that can appear as rows of dots when viewed with an optical microscope. Some pennate diatoms also exhibit a fissure along their longitudinal axis. This is known as a raphe, and is involved in gliding movements made by diatom cells; motile diatoms always possess a raphe. In terms of cell cycle, vegetative cells are diploid and undergo mitosis during normal cell division. Periodically, meiosis produces morphologically identical haploid gametes (isogametes), which fuse to produce a (sometimes binucleate) zygote that develops into an auxospore (from which full-sized vegetative cell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eukaryote
Eukaryotes () are organisms whose cells have a nucleus. All animals, plants, fungi, and many unicellular organisms, are Eukaryotes. They belong to the group of organisms Eukaryota or Eukarya, which is one of the three domains of life. Bacteria and Archaea (both prokaryotes) make up the other two domains. The eukaryotes are usually now regarded as having emerged in the Archaea or as a sister of the Asgard archaea. This implies that there are only two domains of life, Bacteria and Archaea, with eukaryotes incorporated among archaea. Eukaryotes represent a small minority of the number of organisms, but, due to their generally much larger size, their collective global biomass is estimated to be about equal to that of prokaryotes. Eukaryotes emerged approximately 2.3–1.8 billion years ago, during the Proterozoic eon, likely as flagellated phagotrophs. Their name comes from the Greek εὖ (''eu'', "well" or "good") and κάρυον (''karyon'', "nut" or "kernel"). Euka ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Haploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair, which chromosomes naturally exist as. Somatic cells, tissues, and individual organisms can be described according to the number of sets of chromosomes present (the "ploidy level"): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploid or septaploid (7 sets), etc. The generic term polyploid is often used to describe cells with three or more chromosome sets. Virtually all sexually reproducing organisms are made up of somatic cells that are diploid or greater, but ploidy level may vary widely between different organisms, between different tissues within the same organism, and at different stages in an organism's life cycle. Half ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biological Oceanography
Biological oceanography is the study of how organisms affect and are affected by the physics, chemistry, and geology of the oceanographic system. Biological oceanography may also be referred to as ocean ecology, in which the root word of ecology is ''Oikos'' (oικoσ), meaning ‘house’ or ‘habitat’ in Greek. With that in mind, it is of no surprise then that the main focus of biological oceanography is on the microorganisms within the ocean; looking at how they are affected by their environment and how that affects larger marine creatures and their ecosystem.Lalli, Carol M., and Timothy R. Parsons. "Introduction." Biological Oceanography: An Introduction. First Edition ed. Tarrytown, New York: Pergamon, 1993. 7-21. Print. Biological oceanography is similar to marine biology, but is different because of the perspective used to study the ocean. Biological oceanography takes a bottom-up approach (in terms of the food web), while marine biology studies the ocean from a top-down ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Algae Orders
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as ''Chlorella,'' ''Prototheca'' and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to in length. Most are aquatic and autotrophic (they generate food internally) and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the ''Charophyta'', a division of green algae which includes, for example, ''Spirogyra'' and stoneworts. No definition of algae is generally accepted. One definition is that algae "have chlorophyll ''a'' as their primary photosynthetic pigment and lack a sterile covering of cells around their re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clepsydra (genus)
''Clepsydra'' is a genus of diatoms, including the species '' Clepsydra truganiniae''. It was found in Tasmania ) , nickname = , image_map = Tasmania in Australia.svg , map_caption = Location of Tasmania in AustraliaCoordinates: , subdivision_type = Country , subdi ....Vyverman, W.; Sabbe, K.; Mann, D.; Vyverman, R.; Hodgson, D.A.; Muylaert, K.; Vanhoutte, K. (1998). Clepsydra truganiniae gen. nov., spec. nov. prov. from Tasmanian highland lakes and its relationships with other amphoroid diatoms. Biol. Jb. Dodonaea 65: 205. In: Biologisch Jaarboek (Dodonaea). Koninklijk Natuurwetenschappelijk Genootschap Dodonaea: Gent. ISSN 0366-0818 References External linksPaper on new genus Diatom genera Natural history of Tasmania {{Diatom-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Centrales
The Coscinodiscophyceae are a class of diatoms. They are similar to the Centrales, a traditional, paraphyletic subdivision of the heterokont algae known as diatoms. The order is named for the shape of the cell walls (or valves or frustules) of centric diatoms, which are circular or ellipsoid in valve view. The valves often bear radially symmetrical ornamental patterns that can appear as dots when viewed with an optical microscope. Some also bear spines on their valves, which may either increase cell surface area and reduce sinking, or act as a deterrent to zooplankton grazers. Unlike pennate diatoms, centric diatoms never have a raphe. In terms of cell cycle, vegetative cells are diploid and undergo mitosis during normal cell division. In sexual species, oogamous meiosis produces haploid gametes, either ova or sperm cells. These fuse to produce a zygote which expands in size to develop into an auxospore from which full-sized vegetative cells are produced. In some ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fragilariopsis Kerguelensis
''Fragilariopsis kerguelensis'', is a pennate diatom native to the Southern Ocean. It has been characterized as "the most abundant diatom in the Antarctic Seas". Description ''Fragilariopsis kerguelensis'' is a unicellular, phototrophic, microalga with a range in size of 10 - 80 μm. It is encased in a heavily silicified cell wall, called the frustule, and is identified by its unique theca, raphe and striations, which distinguish it from other diatoms. They are native to pelagic environments of the Southern Ocean within a temperature range of -1° to 18° C. ''F. kerguelensis'' is known to form community chains that consist of 20-100 cells and can be up to 300 μm long. Use as a paleoceanographic proxy ''Fragilariopsis kerguelensis'' is well preserved in the fossil record and commonly referenced as a paleoceanographic or paleoclimatic proxy. ''F. kerguelensis'' comprises the largest deposit of biogenic silica in the world (~75%) despite only accounting for 20% of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bacillariophyceae
Bacillariophyceae is a group of pennate diatoms with a raphe (raphids). According to Ruggiero et al., 2015, the diatoms are treated as follows. This treatment largely reflects that used by Algaebase as at 2015, and is also reflected in the current (mid 2020) treatment used iDiatomBase the World Register of Marine Species (WoRMS) of which DiatomBase is a part, and the Catalogue of Life. This treatment is identical to that of Round et al., 1990, except that all diatoms are treated as a single class, Round et al.'s classes are reduced to subclasses, and the latter's original subclasses are omitted. It has 3 subclasses, '' Bacillariophycidae'', ''Coscinodiscophycidae'' and '' Fragilariophycidae'' Subclass Bacillariophycidae Contains the following orders; * Achnanthales (2k) * Bacillariales (3k) * Cymbellales (4k) * Dictyoneidales (17) * Eunotiales (2k) * Lyrellales (38) * Mastogloiales (825) * Naviculales (18k) * Rhopalodiales (527) * Surirellales (2k) * Thalassiophysales (1k) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fragilariophyceae
Fragilariophyceae is a group of pennate diatom The order Pennales is a traditional subdivision of the heterokont algae known as diatoms. The order is named for the shape of the cell walls (or valves or frustules) of pennate diatoms, which are elongated in valve view. The valves may be lin ...s lacking a raphe. Examples It includes the following genera: Fragilariales *'' Ardissonea'' *'' Asterionella'' *'' Asterionellopsis'' *'' Catacombas'' *'' Diatoma'' *'' Fragilaria'' *'' Fragilariforma'' *'' Grammonema'' *'' Hyalosynedra'' *'' Neofragilaria'' *'' Opephora'' *'' Pseudostaurosira'' *'' Punctastriata'' *'' Staurosira'' *'' Staurosirella'' *'' Synedra'' *'' Synedropsis'' *'' Tabularia'' *'' Ulnaria'' Striatellales *'' Hyalosira'' *'' Striatella'' *'' Toxarium'' Other *'' Climacosphenia'' *'' Cyclophora'' *'' Delphineis'' *'' Protoraphis'' *'' Rhabdonema'' *'' Rhaphoneis'' *'' Tabellaria'' *'' Thalassionema'' References Heterokont classes {{Diatom-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Raphe
Raphe (; from Greek ῥαφή, "seam"Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon. revised and augmented throughout by Sir Henry Stuart Jones. with the assistance of. Roderick McKenzie.'' Oxford: Clarendon Press.) has several different meanings in science. In botany and planktology it is commonly used when describing a seam or ridge on diatoms or seeds. In animal anatomy it is used to describe a ridged union of continuous biological tissue. There are several different significant anatomical raphes: * The raphe nucleus is a moderate-size cluster of nuclei found in the brain stem that releases serotonin to the rest of the brain. Selective serotonin reuptake inhibitor (SSRI) antidepressants are believed to act at these nuclei. * The buccal raphe, which is on the cheek and evidence of the fusion of the maxillary and mandibular processes * The lingual raphe on the tongue. Obvious physical evidence of the lingual raphe includes the frenulum (also called the frenum), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Taxonomy (biology)
In biology, taxonomy () is the scientific study of naming, defining ( circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxa (singular: taxon) and these groups are given a taxonomic rank; groups of a given rank can be aggregated to form a more inclusive group of higher rank, thus creating a taxonomic hierarchy. The principal ranks in modern use are domain, kingdom, phylum (''division'' is sometimes used in botany in place of ''phylum''), class, order, family, genus, and species. The Swedish botanist Carl Linnaeus is regarded as the founder of the current system of taxonomy, as he developed a ranked system known as Linnaean taxonomy for categorizing organisms and binomial nomenclature for naming organisms. With advances in the theory, data and analytical technology of biological systematics, the Linnaean system has transformed into a system of modern biological classification intended to reflect the evolu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Auxospore
In certain species of diatoms, auxospores are specialised cells that are produced at key stages in their cell cycle or life history. Auxospores typically play a role in growth processes, sexual reproduction or dormancy.Hoek, C. van den, Mann, D. G. and Jahns, H. M. (1995). Algae : An introduction to phycology', Cambridge University Press, UK. Auxospores are involved in re-establishing the normal size in diatoms are successive mitotic cell divisions leads to a decrease in cell size. This occurs because each daughter cell produced by cell division inherits one of the two valves that make up the frustule (a silica cell wall), and then grows a smaller valve within it. Consequently, each division cycle decreases the average size of diatom cells in a population. When its size becomes too small, a dividing diatom cell produces an auxospore to expand its cell size back to that which is normal for vegetative cells. Auxospores can also play a role in sexual reproduction in diatoms ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
