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Clanculus Villanus
''Clanculus villanus'' is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails. Description The size of an adult shell varies between 10 mm and 21 mm. It differs from the typical forms of ''Clanculus'' in lacking the strong tooth at the base of the columella. The very solid shell has a conical shape. It is cinereous-olive or purplish, lighter beneath, and sparsely dotted with black. The about 6 whorls are slightly convex, and spirally lirate. The body whorl is encircled by about 14 granose separated lirae, of which about 6 are on the upper surface, their interstices bearing spiral stripe. The body whorl is obtusely angular at the periphery, slightly convex beneath, a little descending anteriorly. The aperture is rounded-tetragonal. The outer and basal lips are plicate within. The columella is as in '' Clanculus guineensis'' Gmelin, 1791 but longer. The narrow umbilicus is deep. The parietal wall is slightly calloused and is wri ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. Other ways of defining species include their karyotype, DNA sequence, morphology, behaviour or ecological niche. In addition, paleontologists use the concept of the chronospecies since fossil reproduction cannot be examined. The most recent rigorous estimate for the total number of species of eukaryotes is between 8 and 8.7 million. However, only about 14% of these had been described by 2011. All species (except viruses) are given a two-part name, a "binomial". The first part of a binomial is the genus to which the species belongs. The second part is called the specific name or the specific epithet (in botanical nomenclature, also sometimes i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aperture (mollusc)
The aperture is an opening in certain kinds of mollusc shells: it is the main opening of the shell, where the head-foot part of the body of the animal emerges for locomotion, feeding, etc. The term ''aperture'' is used for the main opening in gastropod shells, scaphopod shells, and also for '' Nautilus'' and ammonite shells. The word is not used to describe bivalve shells, where a natural opening between the two shell valves in the closed position is usually called a ''gape''. Scaphopod shells are tubular, and thus they have two openings: a main anterior aperture and a smaller posterior aperture. As well as the aperture, some gastropod shells have additional openings in their shells for respiration; this is the case in some Fissurellidae (keyhole limpets) where the central smaller opening at the apex of the shell is called an orifice, and in the Haliotidae (abalones) where the row of respiratory openings in the shell are also called orifices. In gastropods In some prosob ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clanculus
''Clanculus'' is a genus of sea snail, marine gastropod molluscs of the family Trochidae, the top shells.Bouchet, P.; Gofas, S. (2010). Clanculus Montfort, 1810. In: Bouchet, P.; Gofas, S.; Rosenberg, G. (2010) World Marine Mollusca database. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=138587 on 2011-04-07 Distribution ''Clanculus'' is an old genus. Fossils found in Italy date from the Pliocene (''C. corallinus'', ''C. elevatus'', ''C. bonfittoi'', ''C. jussieui'') The distribution of this genus is worldwide, individuals of some species sometimes occur in great numbers, from the intertidal zone up to depths of 200 m. Many species can be found in Australia, New Zealand, the Indo-Pacific, Philippines, Sri Lanka, Seychelles, Japan, South Africa, Zanzibar, Indian Ocean, the Red Sea, West Africa, Angola, North Africa and Europe. Shell description These top shells are wide-conical and low spired. Their spirally ribbed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gabon
Gabon (; ; snq, Ngabu), officially the Gabonese Republic (french: République gabonaise), is a country on the west coast of Central Africa. Located on the equator, it is bordered by Equatorial Guinea to the northwest, Cameroon to the north, the Republic of the Congo on the east and south, and the Gulf of Guinea to the west. It has an area of nearly and its population is estimated at million people. There are coastal plains, mountains (the Cristal Mountains and the Chaillu Massif in the centre), and a savanna in the east. Since its independence from France in 1960, the sovereign state of Gabon has had three presidents. In the 1990s, it introduced a multi-party system and a democratic constitution that aimed for a more transparent electoral process and reformed some governmental institutions. With petroleum and foreign private investment, it has the fourth highest HDI in the region (after Mauritius, Seychelles and South Africa) and the fifth highest GDP per capita ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Senegal
Senegal,; Wolof: ''Senegaal''; Pulaar: 𞤅𞤫𞤲𞤫𞤺𞤢𞥄𞤤𞤭 (Senegaali); Arabic: السنغال ''As-Sinighal'') officially the Republic of Senegal,; Wolof: ''Réewum Senegaal''; Pulaar : 𞤈𞤫𞤲𞤣𞤢𞥄𞤲𞤣𞤭 𞤅𞤫𞤲𞤫𞤺𞤢𞥄𞤤𞤭 (Renndaandi Senegaali); Arabic: جمهورية السنغال ''Jumhuriat As-Sinighal'') is a country in West Africa, on the Atlantic Ocean coastline. Senegal is bordered by Mauritania to the north, Mali to the east, Guinea to the southeast and Guinea-Bissau to the southwest. Senegal nearly surrounds the Gambia, a country occupying a narrow sliver of land along the banks of the Gambia River, which separates Senegal's southern region of Casamance from the rest of the country. Senegal also shares a maritime border with Cape Verde. Senegal's economic and political capital is Dakar. Senegal is notably the westernmost country in the mainland of the Old World, or Afro-Eurasia. It owes its name to t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Umbilicus (mollusc)
The umbilicus of a shell is the axially aligned, hollow cone-shaped space within the whorls of a coiled mollusc shell. The term umbilicus is often used in descriptions of gastropod shells, i.e. it is a feature present on the ventral (or under) side of many (but not all) snail shells, including some species of sea snails, land snails, and freshwater snails. The word is also applied to the depressed central area on the planispiral coiled shells of ''Nautilus'' species and fossil ammonites. (These are not gastropods, but shelled cephalopods.) In gastropods The spirally coiled whorls of gastropod shells frequently connect to each other by their inner sides, during the natural course of its formation. This results in a more or less solid central axial pillar, known as the columella. The more intimate the contact between the concave side of the whorls is, the more solid the columella becomes. On the other hand, if this connection is less intense, a hollow space inside the whorls ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Clanculus Guineensis
''Clanculus guineensis'' is a species of sea snail, a marine gastropod mollusk in the family Trochidae, the top snails. Description The size of the shell varies between 15 mm and 25 mm. The very solid shell has a conical shape. It is, rather depressed, angulate at the periphery and deeply umbilicate. Its color is whitish, painted with broad radiating purplish brown stripes above. The base of the shell shows narrow radiating stripes or tessellations of the same shade. The about six whorls are planulate or slightly concave above. The whitish apex is eroded. The succeeding whorls are spirally beaded. The body whorl slightly descends anteriorly, bearing on the upper surface about 7 spiral beaded lirae. The interstices are obliquely finely striate. The base is subplanulate, concentrically sculptured with about 7 or 8 beaded lirae. The rounded aperture is rhomboidal. The outer and basal lips are thick, evenly and finely plicate within. The columella is oblique, deeply ente ... [...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 (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''. It can also b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Body Whorl
The body whorl is part of the morphology of the shell in those gastropod mollusks that possess a coiled shell. The term is also sometimes used in a similar way to describe the shell of a cephalopod mollusk. In gastropods In gastropods, the body whorl, or last whorl, is the most recently formed and largest whorl (or revolution) of a spiral or helical shell, terminating in the aperture. It is called the "body whorl" because most of the body of the soft parts of the animal fits into this whorl. The proportional size of the body whorl in gastropod shells differs greatly according to the actual shell morphology. For shells in which the rate of whorl expansion of each revolution around the axis is very high, the aperture and the body whorl are large, and the shell tends to be low spired. The shell of the abalone is a good example of this kind of shell. The opposite tendency can sometimes create a high spire with very little whorl increase per revolution. In these instances, e. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sea Snail
Sea snail is a common name for slow-moving marine gastropod molluscs, usually with visible external shells, such as whelk or abalone. They share the taxonomic class Gastropoda with slugs, which are distinguished from snails primarily by the absence of a visible 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 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'') are sometimes considered to be sea snails and sometimes listed as land snails. Anatomy Sea snails are a very large group of animals and a very diverse one. 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 when they can move around in the air. These air-breathing species inc ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Whorl (mollusc)
A whorl is a single, complete 360° revolution or turn in the spiral 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 conical tube, the growth of which is coiled into an overall 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 shell has numerous whorls. W ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Columella (gastropod)
The columella (meaning "little column") or (in older texts) pillar is a central anatomical feature of a coiled snail shell, a gastropod shell. The columella is often only clearly visible as a structure when the shell is broken, sliced in half vertically, or viewed as an X-ray image. The columella runs from the apex of the shell to the midpoint of the undersurface of the shell, or the tip of the siphonal canal in those shells which have a siphonal canal. If a snail shell is visualized as a cone of shelly material which is wrapped around a central axis, then the columella more or less coincides spatially with the central axis of the shell. In the case of shells that have an umbilicus, the columella is a hollow structure. The columella of some groups of gastropod shells can have a number of plications or folds (the columellar fold, plaits or plicae), which are usually visible when looking to the inner lip into the aperture of the shell. These folds can be wide or narrow, prominen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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