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Megastraea
''Megastraea'' is a genus of medium-sized to large sea snails with a calcareous operculum, marine gastropod mollusks in the family Turbinidae, the turban snails.Bouchet, P.; Rosenberg, G. (2011). Megastraea McLean, 1970. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=528082 Species Species within this genus were previously placed in the genus ''Astraea''. They include: * '' Megastraea turbanica'' (Dall, 1910) * ''Megastraea undosa ''Megastraea undosa'', common name the wavy turban snail, is a species of sea snail, a marine gastropod mollusk in the family Turbinidae, the turban snails. This species is native to the coast of California. Distribution This species occurs in ...'' (Wood, 1828) References Turbinidae Gastropod genera {{Turbinidae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megastraea Undosa
''Megastraea undosa'', common name the wavy turban snail, is a species of sea snail, a marine gastropod mollusk in the family Turbinidae, the turban snails. This species is native to the coast of California. Distribution This species occurs in the eastern Pacific Ocean from California, USA to Central Baja California, Mexico. Description One of the largest gastropod shells found on the Southern California coast, this species varies between 40 mm and 145 mm. The shell lacks an umbilicus, and has a turbinate-conical shape. Like other shells of the family turbinidae it is composed of a thick inner nacreous layer, covered by a thinner porcellanous layer. In this species both are covered by a dark brown shaggy periostracum in life. The periphery of the shell forms a twisted ridge at the outer edge of each whorl. Each whorl also has regular, coarsely sculpted rows of fine knobs and folds. The base is marked with several spiral cords concentric to the arcuated columell ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megastraea Turbanica
''Megastraea turbanica'', common name the turban star shell, is a species of sea snail, a marine gastropod mollusk in the family Turbinidae, the turban snails. Description The size of the shell attains 150 mm. The shell is moderately large and rather thin. It is brilliantly pearly inside. It is covered with a reddish-brown periostracum which becomes olivaceous on the base. The form is rather depressed with turgid whorls, about six in all. The nucleus is white, blunt, imperfect. The base of the shell is flattened, bordered by a sparsely nodulous carina. The sculpture on the spire is slightly protractive, rounded, and short. It contains rather elevated riblets reaching about half way forward on the whorl from the suture (17 on the last whorl). These end in or are barely separated from the same number of stout nodules at the periphery, with a marked sulcus separating them from a similar row of nodules on the margin of the base. The base contains four somewhat undulated spira ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Megastraea
''Megastraea'' is a genus of medium-sized to large sea snails with a calcareous operculum, marine gastropod mollusks in the family Turbinidae, the turban snails.Bouchet, P.; Rosenberg, G. (2011). Megastraea McLean, 1970. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=528082 Species Species within this genus were previously placed in the genus ''Astraea''. They include: * '' Megastraea turbanica'' (Dall, 1910) * ''Megastraea undosa ''Megastraea undosa'', common name the wavy turban snail, is a species of sea snail, a marine gastropod mollusk in the family Turbinidae, the turban snails. This species is native to the coast of California. Distribution This species occurs in ...'' (Wood, 1828) References Turbinidae Gastropod genera {{Turbinidae-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astraea (gastropod)
''Astraea'' is a genus of medium to large sea snails, marine gastropod mollusks in the family Turbinidae, the turban snails.Bouchet, P. (2012). Astraea Röding, 1798. Accessed through: World Register of Marine Species aWoRMS taxon detailson 2012-03-15 Etymology The Latin genus ''Astraea'' means ''star'', with reference to the star-shape of these snails, also commonly called ''star shells''. Description Shells of species within this genus can reach a size of about . They have the appearance of a smooth conical shell. The outer edges of the coiled whorls are quite flattened, with prominent axial sculpture. Below widely, it is umbilicate and concave. Species Extant species within this genus include: *''Astraea heliotropium'' (Martyn, 1784) Fossil records This genus is known in the fossil records from the Paleocene to the Quaternary (age range: from 61.7 to 0.0 million years ago). Fossils of species within this genus have been found in the sediments of Europe, Australia, United S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Turbinidae
Turbinidae, the turban snails, are a family of small to large marine gastropod molluscs in the superfamily Trochoidea.Bouchet, P. (2014). Turbinidae Rafinesque, 1815. Accessed through: World Register of Marine Species at http://www.marinespecies.org/aphia.php?p=taxdetails&id=503 on 2014-07-28 Description Turbinidae have a strong, thick calcareous operculum readily distinguishing them from the somewhat similar Trochidae or top snails, which have a corneous operculum. This strong operculum serves as a passive defensive structure against predators that try to enter by way of the aperture or that would break the shell at the outer lip. These operculum are rounded ovals that are flat with a swirl design on one side and domed on the other. They are known as Pacific cat's eye or Shiva eye shells or mermaid money, and are used for decorative purposes. Etymology The common name ''turban snail'' presumably refers to the shell's similarity in appearance to a turban. However, the scient ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marine (ocean)
The ocean (also the sea or the world ocean) is the body of salt water that covers approximately 70.8% of the surface of Earth and contains 97% of Earth's water. An ocean can also refer to any of the large bodies of water into which the world ocean is conventionally divided."Ocean." ''Merriam-Webster.com Dictionary'', Merriam-Webster, |
Mollusk
Mollusca is the second-largest phylum of invertebrate animals after the Arthropoda, the members of which are known as molluscs or mollusks (). Around 85,000 extant species of molluscs are recognized. The number of fossil species is estimated between 60,000 and 100,000 additional species. The proportion of undescribed species is very high. Many taxa remain poorly studied. Molluscs are the largest marine phylum, comprising about 23% of all the named marine organisms. Numerous molluscs also live in freshwater and terrestrial habitats. They are highly diverse, not just in size and anatomical structure, but also in behaviour and habitat. The phylum is typically divided into 7 or 8 taxonomic classes, of which two are entirely extinct. Cephalopod molluscs, such as squid, cuttlefish, and octopuses, are among the most neurologically advanced of all invertebrates—and either the giant squid or the colossal squid is the largest known invertebrate species. The gas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropod
The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. There are many thousands of species of sea snails and slugs, as well as freshwater snails, freshwater limpets, and land snails and slugs. The class Gastropoda contains a vast total of named species, second only to the insects in overall number. The fossil history of this class goes back to the Late Cambrian. , 721 families of gastropods are known, of which 245 are extinct and appear only in the fossil record, while 476 are currently extant with or without a fossil record. Gastropoda (previously known as univalves and sometimes spelled "Gasteropoda") are a major part of the phylum Mollusca, and are the most highly diversified class in the phylum, with 65,000 to 80,000 living snail and slug species. The anatomy, behavior, feeding, and re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gastropod Shell
The gastropod shell is part of the body of a Gastropoda, gastropod or snail, a kind of mollusc. The shell is an exoskeleton, which protects from predators, mechanical damage, and dehydration, but also serves for muscle attachment and calcium storage. Some gastropods appear shell-less (slugs) but may have a remnant within the mantle, or in some cases the shell is reduced such that the body cannot be retracted within it (semi-slug). Some snails also possess an operculum that seals the opening of the shell, known as the Aperture (mollusc), aperture, which provides further protection. The study of mollusc shells is known as conchology. The biological study of gastropods, and other molluscs in general, is malacology. Shell morphology terms vary by species group. Shell layers The gastropod shell has three major layers secreted by the Mantle (mollusc), mantle. The calcareous central layer, tracum, is typically made of calcium carbonate precipitated into an organic matrix known as c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operculum (gastropod)
The operculum (; ) is a corneous or calcareous anatomical structure like a trapdoor that exists in many (but not all) groups of sea snails and freshwater snails, and also in a few groups of land snails; the structure is found in some marine and freshwater gastropods, and in a minority of terrestrial gastropods, including the families Helicinidae, Cyclophoridae, Aciculidae, Maizaniidae, Pomatiidae, etc. The operculum is attached to the upper surface of the foot and in its most complete state, it serves as a sort of "trapdoor" to close the aperture of the shell when the soft parts of the animal are retracted. The shape of the operculum varies greatly from one family of gastropods to another. It is fairly often circular, or more or less oval in shape. In species where the operculum fits snugly, its outline corresponds exactly to the shape of the aperture of the shell and it serves to seal the entrance of the shell. Many families have opercula that are reduced in size, and which a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Calcareous
Calcareous () is an adjective meaning "mostly or partly composed of calcium carbonate", in other words, containing lime or being chalky. The term is used in a wide variety of scientific disciplines. In zoology ''Calcareous'' is used as an adjectival term applied to anatomical structures which are made primarily of calcium carbonate, in animals such as gastropods, i.e., snails, specifically about such structures as the operculum, the clausilium, and the love dart. The term also applies to the calcium carbonate tests of often more or less microscopic Foraminifera. Not all tests are calcareous; diatoms and radiolaria have siliceous tests. The molluscs are calcareous, as are calcareous sponges ( Porifera), that have spicules which are made of calcium carbonate. In botany ''Calcareous grassland'' is a form of grassland characteristic of soils containing much calcium carbonate from underlying chalk or limestone rock. In medicine The term is used in pathology, for example i ... [...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 includ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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