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Alvania Dijkstrai
''Alvania dijkstrai'' is a species of minute sea snail in the family Rissoidae Description It has an ovate shell, in height and in length with a thin outer Lip (gastropod), lip. Sometimes two rows of very vague, light brown dots are visible on the ultimate Whorl (mollusc), whorl, one just subsutural and one on the shell base. Distribution It is endemic to the Savage Islands, Selvagens Archipelago off Northwest Africa. References External links Gofas, S.; Le Renard, J.; Bouchet, P. (2001). Mollusca. in: Costello, M.J. et al. (eds), European Register of Marine Species: a check-list of the marine species in Europe and a bibliography of guides to their identification. Patrimoines Naturels. 50: 180-213Conchology.be: image Alvania, dijkstrai Gastropods described in 1998 {{Rissoidae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Snail
Sea snails are slow-moving marine (ocean), marine gastropod Mollusca, molluscs, usually with visible external shells, such as whelk or abalone. They share the Taxonomic classification, taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the absence of a visible Gastropod shell, shell. Definition Determining whether some gastropods should be called sea snails is not always easy. Some species that live in brackish water (such as certain Neritidae, neritids) can be listed as either freshwater snails or marine snails, and some species that live at or just above the high tide level (for example, species in the genus ''Truncatella (gastropod), Truncatella'') are sometimes considered to be sea snails and sometimes listed as land snails. Anatomy Sea snails are a very large and diverse group of animals. Most snails that live in salt water respire using a gill or gills; a few species, though, have a lung, are intertidal, and are active only at low tide w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rissoidae
Rissoidae is a large family of sea snails. Members of the Rissoidae are very small in size and possess an operculum. Distribution and habitat Rissoidae are found worldwide. They live on sandy or gravel bottoms among algae or marine plants. They are also found under rocks in crevices or other sheltered places. Subfamilies The following subfamilies were recognized in the taxonomy of Bouchet & Rocroi of 2005: * Rissoinae Gray, 1847 * Rissoininae Stimpson, 1865 In 2013 the subfamily Rissoininae was elevated to the rank of family Rissoinidae by Criscione F. & Ponder W.F. Genera Genera within Rissoidae include: Powell A. W. B., ''New Zealand Mollusca'', William Collins Publishers Ltd, Auckland, New Zealand 1979 * '' Alvania'' Risso, 1826 * '' Amphirissoa'' Dautzenberg & Fischer, 1897 * '' Archaschenia'' Zhgenti, 1981 † * '' Benthonella'' Dall, 1889 * '' Benthonellania'' Lozouet, 1990 * '' Boreocingula'' Golikov and Kussakin, 1974 * '' Boreomica'' Guzhov, 2017 † * '' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
World Register Of Marine Species
The World Register of Marine Species (WoRMS) is a taxonomic database that aims to provide an authoritative and comprehensive catalogue and list of names of marine organisms. Content The content of the registry is edited and maintained by scientific specialists on each group of organism. These taxonomists control the quality of the information, which is gathered from the primary scientific literature as well as from some external regional and taxon-specific databases. WoRMS maintains valid names of all marine organisms, but also provides information on synonyms and invalid names. It is an ongoing task to maintain the registry, since new species are constantly being discovered and described by scientists; in addition, the nomenclature and taxonomy of existing species is often corrected or changed as new research is constantly being published. Subsets of WoRMS content are made available, and can have separate badging and their own home/launch pages, as "subregisters", such as th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lip (gastropod)
In the shell of gastropod mollusks (a snail shell), the lip is the free margin of the peristome (synonym: peritreme) or aperture (mollusc), aperture (the opening) of the gastropod shell. In dextral (right-handed) shells (most snail shells are right-handed), the right side or outer side of the aperture is known as the outer lip (''labrum''). The left side of the aperture is known as the inner lip or columellar lip (''labium'') if there is a pronounced lip there. In those species where there is no pronounced lip, the part of the body whorl that adjoins the aperture is known as the parietal wall. The outer lip is usually thin and sharp in immature shells, and in some adults (e.g. the land snails ''Helicella'' and ''Bulimulus''). However, in some other land snails and in many marine species the outer lip is ''thickened'' (also called ''callused''), or ''reflected'' (turned outwards). In some other marine species it is curled inwards (''inflected''), as in the cowries such as ''Cypraea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral or whorled growth of a mollusc shell. A spiral configuration of the shell is found in numerous gastropods, but it is also found in shelled cephalopods including ''Nautilus'', ''Spirula'' and the large extinct subclass of cephalopods known as the ammonites. A spiral shell can be visualized as consisting of a long Cone (geometry), conical tube, the growth of which is coiled into an overall Helix, helical or planispiral shape, for reasons of both strength and compactness. The number of whorls which exist in an adult shell of a particular species depends on mathematical factors in the geometric growth, as described in D'Arcy Wentworth Thompson's classic 1917 book ''On Growth and Form'', and by David Raup. The main factor is how rapidly the conical tube expands (or flares-out) over time. When the rate of expansion is low, such that each subsequent whorl is not that much wider than the previous one, then the adult s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Savage Islands
The Savage Islands or Selvagens Islands ( ; also known as the Salvage Islands) are a small Portugal, Portuguese archipelago in the North Atlantic Ocean, south of Madeira and north of the Canary Islands.30,000), white-faced storm-petrel (>80,000), Bulwer's petrel (approximately 4000), North Atlantic little shearwater (1400), Madeiran storm-petrel (1500), yellow-legged gull (50), common tern (>60), roseate tern (<5) and Berthelot's pipit (the only resident bird species); which are subjects of annual scientific expeditions. Many of these species are vulnerable to other local predator bird species, like the yellow-legged gull, which will consume both eggs and chicks (the white-faced storm-petrel and Bulwer's petrel are primarily susceptible). The islands are home to the largest known breeding colony in the world of Cory's shearwater and the only site in the Atlantic where Swinhoe's storm petrel can be regularly found. The S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Africa
Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surface area.Sayre, April Pulley (1999), ''Africa'', Twenty-First Century Books. . With nearly billion people as of , it accounts for about of the world's human population. Demographics of Africa, Africa's population is the youngest among all the continents; the median age in 2012 was 19.7, when the worldwide median age was 30.4. Based on 2024 projections, Africa's population will exceed 3.8 billion people by 2100. Africa is the least wealthy inhabited continent per capita and second-least wealthy by total wealth, ahead of Oceania. Scholars have attributed this to different factors including Geography of Africa, geography, Climate of Africa, climate, corruption, Scramble for Africa, colonialism, the Cold War, and neocolonialism. Despite this lo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alvania
''Alvania'' is a genus of minute sea snails, marine gastropod mollusks or micromollusks in the family Rissoidae. They form a very diversified group within the Rissoidae family. Description ''Alvania'' as currently used may not be monophyletic. The genus ''Alvinia'' has been synonymized with ''Alvania'', until a consistent phylogenetic scheme emerges for the whole group. , is sometimes considered a separate genus.Gofas, S. (2012). Alvinia Monterosato, 1884. Accessed through: World Register of Marine * At http://www.marinespecies.org/aphia.php?p=taxdetails&id=574680 on 18 June 2012 The genus Alvania comprises species with small shells with heights measuring between 1 mm and 7 mm. Their general shape is ovate-conical, reticulated with axial and spirals elements. They have a continuous peristome. Their coloration is variable. Some species such as '' Alvania sculptilis'' have been named twice with the second naming becoming a junior secondary homonym. However, the genus ''Alv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
