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Spicules Of Silicious Sponges
Spicules are structural elements found in most 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 silica. Large spicules visible to the naked eye are referred to as megascleres, while smaller, microscopic ones are termed microscleres. The composition, size, and shape of spicules are major characters in sponge systematics and taxonomy. Overview Sponges are a species-rich clade of the earliest-diverging (most 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 (Demospongiae, Hexactinellida, and Homoscleromorpha) produce skeletons of amorphous silica and on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lamella (cell Biology)
A lamella (plural: "lamellae") in biology refers to a thin layer, membrane or plate of tissue. This is a very broad definition, and can refer to many different structures. Any thin layer of organic tissue can be called a lamella and there is a wide array of functions an individual layer can serve. For example, an intercellular lipid lamella is formed when lamellar disks fuse to form a lamellar sheet. It is believed that these disks are formed from vesicles, giving the lamellar sheet a lipid bilayer that plays a role in water diffusion. Another instance of cellular lamellae can be seen in chloroplasts. Thylakoid membranes are actually a system of lamellar membranes working together, and are differentiated into different lamellar domains. This lamellar system allows plants to convert light energy into chemical energy. Chloroplasts are characterized by a system of membranes embedded in a hydrophobic proteinaceous matrix, or stroma. The basic unit of the membrane system is a flatt ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monorhaphis Chuni
''Monorhaphis'' is a Monotypic taxon#Zoology, monotypic genus of Silicon dioxide, siliceous deep sea Hexactinellid sponges. The single species is the type species ''Monorhaphis chuni'', a sponge known for creating a single giant basal sponge spicule, spicule (G.B.S.) to anchor the sponge in the sediments. The species was described by Franz Eilhard Schulze in 1904 from specimens collected by the German Deep Sea Expedition in 1898-1899. ''Monorhaphis'' is also the only genus in the monotypic family Monorhaphididae. One study provides substantial evidence that an individual of this deep-sea sponge, that forms giant spicules up to 3 meters long, is about 11,000 years old. Five other individuals collected from depths of 1,100 to 2,100 meters at three widely separated locations in the western Pacific Ocean were estimated to be 6,000 to 18,000 (±1,000) years old and grew radially at about 140 μm per 1,000 years. The samples were shown to record deep ocean silica geochemistry througho ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Valdivia
Valdivia (; Mapuche: Ainil) is a city and commune in southern Chile, administered by the Municipality of Valdivia. The city is named after its founder Pedro de Valdivia and is located at the confluence of the Calle-Calle, Valdivia, and Cau-Cau Rivers, approximately east of the coastal towns of Corral and Niebla. Since October 2007, Valdivia has been the capital of Los Ríos Region and is also the capital of Valdivia Province. The national census of 2017 recorded the commune of Valdivia as having 166,080 inhabitants (''Valdivianos''), of whom 150,048 were living in the city. The main economic activities of Valdivia include tourism, wood pulp manufacturing, forestry, metallurgy, and beer production. The city is also the home of the Austral University of Chile, founded in 1954 and the Centro de Estudios Científicos. The city of Valdivia and the Chiloé Archipelago were once the two southernmost outliers of the Spanish Empire. From 1645 to 1740 the city depended directly on the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Filigree
Filigree (also less commonly spelled ''filagree'', and formerly written ''filigrann'' or ''filigrene'') is a form of intricate metalwork used in jewellery and other small forms of metalwork. In jewellery, it is usually of gold and silver, made with tiny beads or twisted threads, or both in combination, soldered together or to the surface of an object of the same metal and arranged in artistic motifs. It often suggests lace and remains popular in Indian and other Asian metalwork. It was popular as well in Italian, French and Portuguese metalwork from 1660 to the late 19th century. It should not be confused with ajoure jewellery work, the ajoure technique consisting of drilling holes in objects made of sheet metal. The English word filigree is shortened from the earlier use of ''filigreen'' which derives from Latin "filum" meaning thread and "granum" grain, in the sense of small bead. The Latin words gave ''filigrana'' in Italian which itself became ''filigrane'' in 17th- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body Plan
A body plan, ( ), or ground plan is a set of morphological features common to many members of a phylum of animals. The vertebrates share one body plan, while invertebrates have many. This term, usually applied to animals, envisages a "blueprint" encompassing aspects such as symmetry, layers, segmentation, nerve, limb, and gut disposition. Evolutionary developmental biology seeks to explain the origins of diverse body plans. Body plans have historically been considered to have evolved in a flash in the Ediacaran biota; filling the Cambrian explosion with the results, and a more nuanced understanding of animal evolution suggests gradual development of body plans throughout the early Palaeozoic. Recent studies in animals and plants started to investigate whether evolutionary constraints on body plan structures can explain the presence of developmental constraints during embryogenesis such as the phenomenon referred to as phylotypic stage. History Among the pioneering zoologist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Siliceous Sponge
The siliceous sponges form a major group of the phylum Porifera, consisting of classes Demospongiae and Hexactinellida. They are characterized by spicules made out of silicon dioxide, unlike calcareous sponges. Individual siliachoates (silica skeleton scaffolding) can be arranged tightly within the sponginocyte or crosshatched and fused together. Siliceous spicules come in two sizes called megascleres and microscleres. Systematics Most studies support the monophyly of siliceous sponges. The group, as a part of the phylum Porifera, has been named ''Silicispongia'' Schmidt, 1862 and ''Silicea'' Bowerbank, 1864. ''Silicarea'' is a proposed new phylum based on molecular studies of the phylum Porifera. It consists of the Poriferan classes Demospongiae and Hexactinellida. Some scientists believe that Porifera is polyphyletic/paraphyletic, and that some sponges, the Calcarea, are a separate phylum which was the first to diverge from the main line of kingdom Animalia. Silicarea is ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Franz Eilhard Schulze
Franz Eilhard Schulze (22 March 1840 – 2 November 1921) was a German anatomist and zoologist born in Eldena, near Greifswald. Biography He studied at the Universities of Bonn and Rostock. In 1863, he received his doctorate from Rostock, where he subsequently became a lecturer of anatomy (1864) and an associate professor of comparative anatomy (1865). In 1871 he established the zoological institute at the University of Rostock.See entry oFranz Eilhard Schulzein Catalogus Professorum Rostochiensium Later on, he served as a professor at the Universities of Graz and Berlin. In 1872, he took part in the "Pomerania" expedition to the North Sea. For several years during the 1890s, he was president of the German Zoological Society (''Deutsche Zoologische Gesellschaft''). He made contributions in his studies on the anatomy and developmental history of invertebrates, in particular, his research and publications in regards to sea-sponges. He was especially interested in a class of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Challenger Expedition
The ''Challenger'' expedition of 1872–1876 was a scientific program that made many discoveries to lay the foundation of oceanography. The expedition was named after the naval vessel that undertook the trip, . The expedition, initiated by William Benjamin Carpenter, was placed under the scientific supervision of Sir Charles Wyville Thomson—of the University of Edinburgh and Merchiston Castle School—assisted by five other scientists, including Sir John Murray, a secretary-artist and a photographer. The Royal Society of London obtained the use of ''Challenger'' from the Royal Navy and in 1872 modified the ship for scientific tasks, equipping it with separate laboratories for natural history and chemistry. The expedition, led by Captain George Nares, sailed from Portsmouth, England, on 21 December 1872. Other naval officers included Commander John Maclear. – pages 19 and 20 list the civilian staff and naval officers and crew, along with changes that took place during the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multicellular Animal
A multicellular organism is an organism that consists of more than one cell, in contrast to unicellular organism. All species of animals, land plants and most fungi are multicellular, as are many algae, whereas a few organisms are partially uni- and partially multicellular, like slime molds and social amoebae such as the genus ''Dictyostelium''. Multicellular organisms arise in various ways, for example by cell division or by aggregation of many single cells. Colonial organisms are the result of many identical individuals joining together to form a colony. However, it can often be hard to separate colonial protists from true multicellular organisms, because the two concepts are not distinct; colonial protists have been dubbed "pluricellular" rather than "multicellular". There are also multinucleate though technically unicellular organisms that are macroscopic, such as the xenophyophorea that can reach 20 cm. Evolutionary history Occurrence Multicellularity has evolved ind ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Porifera
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have 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. Sponges were first to branch off the evolutionary tree from the last common ancestor of all animals, making them the sister group of all other animals. Etymology The term ''sponge'' derives from the Ancient Greek word ( 'sponge'). Overview Sponges are similar to other animals in that they are multicellular, hete ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
