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Aquilonastra Burtoni
''Aquilonastra burtoni'' is a species of small sea star from the family Asterinidae from the Red Sea which has colonised the eastern Mediterranean by Lessepsian migration through the Suez Canal, although the Mediterranean populations are clonal reproducing through fissiparous asexual reproduction. It was originally described in 1840 by the English zoologist and philatelist John Edward Gray. Description ''Aquilonastra burtoni'' is a small species of sea star with up to 8 rays, frequently 7, they frequently demonstrate an asymmetrical form after fissiparous division while the form of larger specimens is often symmetrical with 5 equal rays; there is an inconspicuous madreporite in most interradii. The rays narrow basally, tapering to a narrow rounded distal part which is finger-like. Each of the plates on the oral surface has a grouping of 3 crowded mobile tapering spines in their centres, while those of the dorsal surface have a dense group of short tubercles. It is a greenish gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Edward Gray
John Edward Gray, FRS (12 February 1800 – 7 March 1875) was a British zoologist. He was the elder brother of zoologist George Robert Gray and son of the pharmacologist and botanist Samuel Frederick Gray (1766–1828). The same is used for a zoological name. Gray was keeper of zoology at the British Museum in London from 1840 until Christmas 1874, before the natural history holdings were split off to the Natural History Museum. He published several catalogues of the museum collections that included comprehensive discussions of animal groups and descriptions of new species. He improved the zoological collections to make them amongst the best in the world. Biography Gray was born in Walsall, but his family soon moved to London, where Gray studied medicine. He assisted his father in writing ''The Natural Arrangement of British Plants'' (1821). After being blackballed by the Linnean Society of London, Gray shifted his interest from botany to zoology. He began his zoologica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Of Oman
The Gulf of Oman or Sea of Oman ( ar, خليج عمان ''khalīj ʿumān''; fa, دریای عمان ''daryâ-ye omân''), also known as Gulf of Makran or Sea of Makran ( ar, خلیج مکران ''khalīj makrān''; fa, دریای مکران ''daryâ-ye makrān''), is a gulf that connects the Arabian Sea with the Strait of Hormuz, which then runs to the Persian Gulf. It borders Iran and Pakistan on the north, Oman on the south, and the United Arab Emirates on the west. Extent The International Hydrographic Organization defines the limits of the Gulf of Oman as follows: Exclusive economic zone Exclusive economic zones in Persian Gulf: Bordering countries Coastline length of bordering countries: # - 850 km coastline # - 750 km coastline # - 50 km coastline # - 50 km coastline Alternative names The Gulf of Oman historically and geographically has been referred to with different names by Arabian, Iranian, Indian, Pakistani and European geogra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sensu Stricto
''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular concept, but it also appears in expressions that indicate the convention or context of the usage. Common qualifiers ''Sensu'' is the ablative case of the noun ''sensus'', here meaning "sense". It is often accompanied by an adjective (in the same case). Three such phrases are: *''sensu stricto'' – "in the strict sense", abbreviation ''s.s.'' or ''s.str.''; *''sensu lato'' – "in the broad sense", abbreviation ''s.l.''; *''sensu amplo'' – "in a relaxed, generous (or 'ample') sense", a similar meaning to ''sensu lato''. Søren Kierkegaard uses the phrase ''sensu eminenti'' to mean "in the pre-eminent r most important or significantsense". When appropriate, comparative and superlative adjectives may also be used to convey the meaning o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquilonastra Yairi
''Aquilonastra'' is a genus of small sea stars within the family Asterinidae. It has over 20 described species. Description ''Aquilonastra'' has generally five rays, except fissiparous species which have five to eight ones. It looks like a star, as inter-radial margins are deeply incurved. List of species According to World Register of Marine Species and O'Loughlin & Rowe 2006:. * ''Aquilonastra anomala'' (H.L. Clark, 1921) * '' Aquilonastra batheri'' (Goto, 1914) * '' Aquilonastra burtoni'' (Gray, 1840) * '' Aquilonastra byrneae'' O'Loughlin & Rowe, 2006 * '' Aquilonastra cepheus'' (Muller & Troschel, 1842) * ''Aquilonastra chantalae'' O'Loughlin & MacKenzie, 2013 * '' Aquilonastra colemani'' O'Loughlin & Rowe, 2006 * ''Aquilonastra conandae'' O'Loughlin & Rowe, 2006 * '' Aquilonastra corallicola'' (Marsh, 1977) * '' Aquilonastra coronata'' (von Martens, 1866) * ''Aquilonastra doranae'' O'Loughlin & Rowe, 2006 * ''Aquilonastra halseyae'' O'Loughlin & Rowe, 2006 * ''Aquilo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spermatogenesis
Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubules. These cells are called spermatogonial stem cells. The mitotic division of these produces two types of cells. Type A cells replenish the stem cells, and type B cells differentiate into primary spermatocytes. The primary spermatocyte divides meiotically (Meiosis I) into two secondary spermatocytes; each secondary spermatocyte divides into two equal haploid spermatids by Meiosis II. The spermatids are transformed into spermatozoa (sperm) by the process of spermiogenesis. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to two cells, the secondary spermatocytes, and the two secondary spermatocytes by their subdivision produce four spermatozoa and four haploid cells. Spermatozoa are ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eudistoma
''Eudistoma'' is a genus of sea squirts belonging to the class Ascidiacea. It was first described in 1909 by Maurice Caullery. Originally it was thought to be a subgenus of '' Distoma''. ''Eudistoma'' is the most species-rich genus in the family Polycitordae, with 124 valid species as of 2014. They are found in tropical and temperate waters; some species are also found in the Antarctic and subtropical area. Description In 1909 Caullery described ''Eudistoma'' as a subgenus of ''Distoma'' due to the rows of stigmata in the pharynx. In 1917 Ritter and Forsyth described it as a separate genus without explanation. Three subsequent papers published in 1919, 1921 and 1942 all considered it to be a subgenus of ''Polycitor''. ''Eudistoma'' was finally considered a valid genus in 1945 due to "the three rows of pharyngeal slits, long esophagus, flat stomach in the posterior region of the abdomen, very conspicuous longitudinal muscles extending from the pharynx to the end of the abdomen a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Trididemnum
''Trididemnum'' is a genus of tunicates belonging to the family Didemnidae. The genus has cosmopolitan distribution In biogeography, cosmopolitan distribution is the term for the range of a taxon that extends across all or most of the world in appropriate habitats. Such a taxon, usually a species, is said to exhibit cosmopolitanism or cosmopolitism. The ext .... Species Species: *'' Trididemnum alexi'' *'' Trididemnum alleni'' *'' Trididemnum amiculum'' *'' Trididemnum areolatum'' *'' Trididemnum auriculatum'' *'' Trididemnum banneri'' *'' Trididemnum caelatum'' *'' Trididemnum cerebriforme'' *'' Trididemnum cereum'' *'' Trididemnum clinides'' *'' Trididemnum cristatum'' *'' Trididemnum cyanophorum'' *'' Trididemnum cyclops'' *'' Trididemnum delesseriae'' *'' Trididemnum discrepans'' *'' Trididemnum dispersum'' *'' Trididemnum erythraeum'' *'' Trididemnum farrago'' *'' Trididemnum fetia'' *'' Trididemnum grandistellatum'' *'' Trididemnum granosum'' *'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ascidiacea
Ascidiacea, commonly known as the ascidians, tunicates (in part), and sea squirts (in part), is a polyphyletic class in the subphylum Tunicata of sac-like marine invertebrate filter feeders. Ascidians are characterized by a tough outer "tunic" made of a polysaccharide. Ascidians are found all over the world, usually in shallow water with salinities over 2.5%. While members of the Thaliacea and Larvacea (Appendicularia) swim freely like plankton, sea squirts are sessile animals after their larval phase: they then remain firmly attached to their substratum, such as rocks and shells. There are 2,300 species of ascidians and three main types: solitary ascidians, social ascidians that form clumped communities by attaching at their bases, and compound ascidians that consist of many small individuals (each individual is called a zooid) forming colonies up to several meters in diameter. Sea squirts feed by taking in water through a tube, the oral siphon. The water enters the mouth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cyprus
Cyprus ; tr, Kıbrıs (), officially the Republic of Cyprus,, , lit: Republic of Cyprus is an island country located south of the Anatolian Peninsula in the eastern Mediterranean Sea. Its continental position is disputed; while it is geographically in Western Asia, its cultural ties and geopolitics are overwhelmingly Southern European. Cyprus is the third-largest and third-most populous island in the Mediterranean. It is located north of Egypt, east of Greece, south of Turkey, and west of Lebanon and Syria. Its capital and largest city is Nicosia. The northeast portion of the island is ''de facto'' governed by the self-declared Turkish Republic of Northern Cyprus, which was established after the 1974 invasion and which is recognised as a country only by Turkey. The earliest known human activity on the island dates to around the 10th millennium BC. Archaeological remains include the well-preserved ruins from the Hellenistic period such as Salamis and Kourion, and Cypr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aquilonastra
''Aquilonastra'' is a genus of small sea stars within the family Asterinidae. It has over 20 described species. Description ''Aquilonastra'' has generally five rays, except fissiparous species which have five to eight ones. It looks like a star, as inter-radial margins are deeply incurved. List of species According to World Register of Marine Species and O'Loughlin & Rowe 2006:. * '' Aquilonastra anomala'' (H.L. Clark, 1921) * '' Aquilonastra batheri'' (Goto, 1914) * '' Aquilonastra burtoni'' (Gray, 1840) * '' Aquilonastra byrneae'' O'Loughlin & Rowe, 2006 * '' Aquilonastra cepheus'' (Muller & Troschel, 1842) * '' Aquilonastra chantalae'' O'Loughlin & MacKenzie, 2013 * '' Aquilonastra colemani'' O'Loughlin & Rowe, 2006 * '' Aquilonastra conandae'' O'Loughlin & Rowe, 2006 * '' Aquilonastra corallicola'' (Marsh, 1977) * '' Aquilonastra coronata'' (von Martens, 1866) * '' Aquilonastra doranae'' O'Loughlin & Rowe, 2006 * '' Aquilonastra halseyae'' O'Loughlin & Rowe, 2006 * '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
