Amastra Fraterna
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Amastra Fraterna
''Amastra fraterna'' is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Amastridae. Description The length of the shell attains 10 mm, its diameter 5.5 mm The shell is sinistral, ovate-turriform, and thin, with an impressed suture. It consists of to 7 whorls, which are slightly convex and longitudinally striated. The surface is covered with a brown to blackish-corneous epidermis, lending a natural and earthy appearance. The aperture is ovate and of moderate size, with an unexpanded and acute peristome. A moderate lamina enhances the columella, contributing to the shell's structural elegance. The shell is notably more inflated compared to any member of the ''Amastra soror'' group from Maui. It is entirely covered with a thin, dark-brown to black cuticle, which is often worn away near the front of the aperture, revealing the underlying purple-brown coloration. The typical form features a nearly straight-sided spire and co ...
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Species
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. It is the basic unit of Taxonomy (biology), classification and a taxonomic rank of an organism, as well as a unit of biodiversity. Other ways of defining species include their karyotype, DNA sequence, morphology (biology), morphology, behaviour, or ecological niche. In addition, palaeontologists 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. About 14% of these had been described by 2011. All species (except viruses) are given a binomial nomenclature, two-part name, a "binomen". The first part of a binomen is the name of a genus to which the species belongs. The second part is called the specific name (zoology), specific name or the specific ...
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Amastra Soror
''Amastra soror'' is a species of air-breathing land snail, a terrestrial pulmonate gastropod mollusc in the family Amastridae. ;Subspecies: * ''Amastra soror interjecta'' Hyatt & Pilsbry, 1911 * ''Amastra soror laticeps'' Hyatt & Pilsbry, 1911 * ''Amastra soror soror'' (Newcomb, 1854) Description The length of the shell attains 11.6 mm. (Original description) The shell is sinistral and conically turreted, comprising seven rounded whorls with a deeply impressed suture. The aperture is small and subovate, with a simple outer lip. The columella is very short, ending in a twisted plicate tooth. The thin epidermis is dark corneous on the upper portion and light corneous below. Distribution This species is endemic to Hawaii and occurs on Maui Maui (; Hawaiian language, Hawaiian: ) is the second largest island in the Hawaiian archipelago, at 727.2 square miles (1,883 km2). It is the List of islands of the United States by area, 17th-largest in the United States. Maui ...
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Lanai
Lānai is the sixth-largest of the Hawaiian Islands and the smallest publicly accessible inhabited island in the chain. It is colloquially known as the Pineapple Island because of its past as an island-wide pineapple plantation. The island's only settlement of note is the small town of Lānai City. The island is 98% owned by Larry Ellison, cofounder and chairman of Oracle Corporation; the remaining 2% is owned by the state of Hawaii or individual homeowners. Lānai has a land area of , making it the 43rd largest island in the United States. It is separated from the island of Molokai by the Kalohi Channel to the north, and from Maui by the Auau Channel to the east. The United States Census Bureau defines Lānai as Census Tract 316 of Maui County. Its total population rose to 3,367 as of the 2020 United States census, up from 3,193 as of the 2000 census and 3,131 as of the 2010 census. As visible via satellite imagery, many of the island's landmarks are accessible only by ...
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Hawaii
Hawaii ( ; ) is an island U.S. state, state of the United States, in the Pacific Ocean about southwest of the U.S. mainland. One of the two Non-contiguous United States, non-contiguous U.S. states (along with Alaska), it is the only state not on the North American mainland, the only state that is an archipelago, and the only state in the tropics. Hawaii consists of 137 volcanic islands that comprise almost the entire Hawaiian Islands, Hawaiian archipelago (the exception, which is outside the state, is Midway Atoll). Spanning , the state is Physical geography, physiographically and Ethnology, ethnologically part of the Polynesian subregion of Oceania. Hawaii's ocean coastline is consequently the List of U.S. states and territories by coastline, fourth-longest in the U.S., at about . The eight main islands, from northwest to southeast, are Niihau, Niihau, Kauai, Kauai, Oahu, Oahu, Molokai, Molokai, Lanai, Lānai, Kahoʻolawe, Kahoolawe, Maui, and Hawaii (island), Hawaii, a ...
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Endemism
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be ''endemic'' to that particular part of the world. An endemic species can also be referred to as an ''endemism'' or, in scientific literature, as an ''endemite''. Similarly, many species found in the Western ghats of India are examples of endemism. Endemism is an important concept in conservation biology for measuring biodiversity in a particular place and evaluating the risk of extinction for species. Endemism is also of interest in evolutionary biology, because it provides clues about how changes in the environment cause species to undergo range shifts (potentially expanding their range into a larger area or b ...
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Body Whorl
The body whorl is part of the morphology (biology), morphology of the gastropod shell, 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 (mollusc), whorl (or revolution) of a spiral or Helix, helical Gastropod shell, shell, terminating in the Aperture (mollusc), 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 Spire (mollusc), spired. The shell of the abalone is a good example of this kind of shell. The opposite ...
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Spire (mollusc)
A spire is a part of the coiled shell of molluscs. The spire consists of all of the whorls except for the body whorl. Each spire whorl represents a rotation of 360°. A spire is part of the shell of a snail, a gastropod mollusc, a gastropod shell, and also the whorls of the shell in ammonites, which are fossil shelled cephalopods. In textbook illustrations of gastropod shells, the tradition (with a few exceptions) is to show most shells with the spire uppermost on the page. The spire, when it is not damaged or eroded, includes the protoconch (also called the nuclear whorls or the larval shell), and most of the subsequent teleoconch whorls (also called the postnuclear whorls), which gradually increase in area as they are formed. Thus the spire in most gastropods is pointed, the tip being known as the " apex". The word "spire" is used, in an analogy to a church spire or rock spire, a high, thin, pinnacle. The "spire angle" is the angle, as seen from the apex, at which a s ...
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Maui
Maui (; Hawaiian language, Hawaiian: ) is the second largest island in the Hawaiian archipelago, at 727.2 square miles (1,883 km2). It is the List of islands of the United States by area, 17th-largest in the United States. Maui is one of Maui County, Hawaii, Maui County's five islands, along with Molokai, Molokai, Lanai, Lānai, Kahoʻolawe, Kahoolawe, and Molokini. In 2020, Maui had a population of 168,307, the third-highest of the Hawaiian Islands, behind Oahu, Oahu and Hawaii (island), Hawaii Island. Kahului, Hawaii, Kahului is the largest census-designated place (CDP) on the island, with a 2020 population of 28,219. It is Maui's commercial and financial hub. Wailuku, Hawaii, Wailuku is the county seat and was the third-largest CDP . Other significant populated areas include Kihei, Hawaii, Kīhei (including Wailea, Hawaii, Wailea and Makena, Hawaii, Makena in the Kihei Town CDP), Lahaina, Hawaii, Lāhainā (including Kaanapali, Kāanapali and Kapalua in the Lāhainā T ...
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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 (mollusc), 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 (mollusc), aperture of the shell. These ...
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Land Snail
A land snail is any of the numerous species of snail that live on land, as opposed to the sea snails and freshwater snails. ''Land snail'' is the common name for terrestrial molluscs, terrestrial gastropod mollusks that have gastropod shell, shells (those without shells are known as slugs). However, it is not always easy to say which species are terrestrial, because some are more or less amphibious between land and fresh water, and others are relatively amphibious between land and salt water. Land snails are a Polyphyly, polyphyletic group comprising at least ten independent evolutionary transitions to terrestrial life (the last common ancestor of all gastropods was marine). The majority of land snails are pulmonates that have a lung and breathe air. Most of the non-pulmonate land snails belong to lineages in the Caenogastropoda, and tend to have a gill and an operculum (gastropod), operculum. The largest clade of non-pulmonate land snails is the Cyclophoroidea, with more than 7,0 ...
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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 (bivalve), 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 (mollusc), apex of the shell is called an orifice, and in the Haliotidae (abalone) where the row of respiratory openings in the shell are also called orifices. In ...
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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 ...
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