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Corneous
Corneous is a biological and medical term meaning horny, in other words made out of a substance similar to that of horns and hooves in some mammals. The word is generally used to describe natural or pathological anatomical structures made out of a hard layer of protein. In mammals this protein would usually be keratin. The word corneous is also often used to describe the operculum of a snail, a gastropod mollusc. Not all gastropods have opercula, but in the great majority of those that do have one, the operculum is corneous. (However in several genera within a few families including the marine Naticidae and the terrestrial Pomatiidae, the operculum is primarily calcareous, in other words mostly made of calcium carbonate.) Corneous opercula are made out of the protein conchiolin Conchiolins (sometimes referred to as conchins) are complex proteins which are secreted by a mollusc's outer epithelium (the mantle). These proteins are part of a matrix of organic macromolecul ... [...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 whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keratins
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, horns, claws, hooves, and the outer layer of skin among vertebrates. Keratin also protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. Excessive keratinization participate in fortification of certain tissues such as in horns of cattle and rhinos, and armadillos' osteoderm. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin comes in two types, the primitive, softer forms found in all vertebrates and harder, derived forms found only amon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Naticidae
Naticidae, common name moon snails or necklace shells, is a family of medium to large-sized predatory sea snails, marine gastropod molluscs in the clade Littorinimorpha. The shells of the species in this family are mostly globular in shape. Naticidae is the only family in the superfamily Naticoidea. It has been estimated that worldwide there are about 260–270 recent species of naticid snails. This group is assumed to have originated in the late Triassic or in the early Jurassic. Members of this family can be recognized by the shape of their shells, distinct appearance, or by their predatory behavior. Distribution Naticids are widely distributed and occur worldwide. The greatest diversity of both species and genera is found in tropical regions. Even so, naticid snails are also plentiful in temperate, Arctic and Antarctic waters. Habitat Moon snails live on sandy substrates, at a great variety of depths depending on the species (from the intertidal zone to thousands of meter ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Keratin
Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, horns, claws, hooves, and the outer layer of skin among vertebrates. Keratin also protects epithelial cells from damage or stress. Keratin is extremely insoluble in water and organic solvents. Keratin monomers assemble into bundles to form intermediate filaments, which are tough and form strong unmineralized epidermal appendages found in reptiles, birds, amphibians, and mammals. Excessive keratinization participate in fortification of certain tissues such as in horns of cattle and rhinos, and armadillos' osteoderm. The only other biological matter known to approximate the toughness of keratinized tissue is chitin. Keratin comes in two types, the primitive, softer forms found in all vertebrates and harder, derived forms found only among saur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mammal Anatomy
Mammals () are a group of vertebrate animals constituting the class (biology), class Mammalia (), characterized by the presence of mammary glands which in Female#Mammalian female, females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or hair, and three ossicles, middle ear bones. These characteristics distinguish them from reptiles (including birds) from which they Genetic divergence, diverged in the Carboniferous, over 300 million years ago. Around 6,400 extant taxon, extant species of mammals have been described divided into 29 Order (biology), orders. The largest Order (biology), orders, in terms of number of species, are the rodents, bats, and Eulipotyphla (hedgehogs, Mole (animal), moles, shrews, and others). The next three are the Primates (including humans, apes, monkeys, and others), the Artiodactyla (cetaceans and even-toed ungulates), and the Carnivora (cats, dogs, pinniped, seals, and others). In terms of cladistic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Animal Anatomy
Anatomy () is the branch of biology concerned with the study of the structure of organisms and their parts. Anatomy is a branch of natural science that deals with the structural organization of living things. It is an old science, having its beginnings in prehistoric times. Anatomy is inherently tied to developmental biology, embryology, comparative anatomy, evolutionary biology, and phylogeny, as these are the processes by which anatomy is generated, both over immediate and long-term timescales. Anatomy and physiology, which study the structure and function of organisms and their parts respectively, make a natural pair of related disciplines, and are often studied together. Human anatomy is one of the essential basic sciences that are applied in medicine. The discipline of anatomy is divided into macroscopic and microscopic. Macroscopic anatomy, or gross anatomy, is the examination of an animal's body parts using unaided eyesight. Gross anatomy also includes the branch of s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dictionary
A dictionary is a listing of lexemes from the lexicon of one or more specific languages, often arranged alphabetically (or by radical and stroke for ideographic languages), which may include information on definitions, usage, etymologies, pronunciations, translation, etc.Webster's New World College Dictionary, Fourth Edition, 2002 It is a lexicographical reference that shows inter-relationships among the data. A broad distinction is made between general and specialized dictionaries. Specialized dictionaries include words in specialist fields, rather than a complete range of words in the language. Lexical items that describe concepts in specific fields are usually called terms instead of words, although there is no consensus whether lexicology and terminology are two different fields of study. In theory, general dictionaries are supposed to be semasiological, mapping word to definition, while specialized dictionaries are supposed to be onomasiological, first ident ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conchiolin
Conchiolins (sometimes referred to as conchins) are complex proteins which are secreted by a mollusc's outer epithelium (the mantle). These proteins are part of a matrix of organic macromolecules, mainly proteins and polysaccharides, that assembled together form the microenvironment where crystals nucleate and grow. This organic matrix also holds and binds to the crystals of aragonite which give such shells their stiffness. The ions necessary to form calcium carbonate are also secreted by the mantle, but it is the tailored environment created by the organic matrix which causes aragonite (rather than calcite) crystals to nucleate, in much the same way that collagen nucleates hydroxyapatite crystals. Conchiolin serves as a relatively flexible, crack-deflecting matrix for the mineral aggregate particles; its strength and the strong bonding of perlucin can in some cases (such as in the formation of nacre) give the finished material an impressive level of toughness. As ... [...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 e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pomatiidae
The family Pomatiidae is a taxonomic family of small operculate land snails, terrestrial gastropod mollusks that can be found over the warmer parts of the Old World. In the older literature, this family is designated as Pomatiasidae. This family is a lineage closely related to the Littorinidae (periwinkles) common in coastal habitat. They have adapted to terrestrial life and are thus sometimes called "land winkles". They are defined by a chalky operculum at the rear end of the body, the shape of their thick shell and their mouth and a characteristic spiral sculpture. The sexes are separate and can sometimes be recognised because the female shell is slightly larger than the male shell. Taxonomy According to the Taxonomy of the Gastropoda (Bouchet & Rocroi, 2005), the family Pomatiidae consisted of two subfamilies: *subfamily Pomatiinae Newton, 1891 (1828) - synonyms: Cyclostomatidae Menke, 1828; Cyclotopsinae Kobelt & Möllendorff, 1898; Ericiidae Wenz, 1915 *subfamily Annula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Horn
Horn most often refers to: *Horn (acoustic), a conical or bell shaped aperture used to guide sound ** Horn (instrument), collective name for tube-shaped wind musical instruments *Horn (anatomy), a pointed, bony projection on the head of various animals, either the "true" horn, or other horn-like growths ** Horn, a colloquial reference to keratin, the substance that is the main component of the tissue that sheaths the bony core of horns and hoofs of various animals Horn may also refer to: Audio * Horn loudspeaker * Vehicle horn ** Train horn Personal name * Horn (surname) * Freyja, also known as ''Hörn'', a Norse goddess of love, beauty, fertility, war and death Places * Cape Horn, the southernmost point of South America * Horn of Africa, a peninsula in northeast Africa * Horn (district), a district of the state of Lower Austria in Austria ** Horn, Austria, a small town, capital of the Horn District * Horn, Germany, a municipality in Rhineland-Palatinate, Germany * Horn, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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