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Pinctada Mazatlanica
''Pinctada mazatlanica'' is a species of tropical marine bivalve mollusc in the family Pteriidae, the pearl oysters. It is known by the English common names pearl oyster, Mazatlan pearl oyster, and Panama pearl oyster. Spanish common names include ''madre perla'', and ''ostra perlifera panameña''. This mollusc was first described to science in 1856 by conchologist Sylvannus Charles Thorp Hanley. ''Pinctada mazatlanica'' produces gem-quality pearls and was the basis of a pearling industry in the Gulf of California for centuries. Description Valves are shallow, attaining a maximum length of 20 cm (8 inches). They are generally round with minimal, if any, wing-like extensions on the hinge margin which are found in other species of its family. In life, the shell has a shaggy periostracum, or skin-like coating. The exterior of the valves is grayish-brown and scaly. The interior is brilliantly nacreous, iridescent mother-of-pearl. Distribution ''Pinctada mazatlanica'' is ... [...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] |
Sequential Hermaphroditism
Sequential hermaphroditism (called dichogamy in botany) is a type of hermaphroditism that occurs in many fish, gastropods, and plants. Sequential hermaphroditism occurs when the individual changes its sex at some point in its life. In particular, a sequential hermaphrodite produces eggs (female gametes) and sperm (male gametes) at different stages in life. Species that can undergo these changes from one sex to another do so as a normal event within their reproductive cycle that is usually cued by either social structure or the achievement of a certain age or size. In animals, the different types of change are male to female (protandry or protandrous hermaphroditism), female to male (protogyny or protogynous hermaphroditism), bidirectional (serial or bidirectional hermaphroditism). Both protogynous and protandrous hermaphroditism allow the organism to switch between functional male and functional female. Bidirectional hermaphrodites have the capacity for sex change in either directi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
The Pearl (novel)
''The Pearl'' is a novella by the American author John Steinbeck. The story, first published in 1947, follows a pearl diver, Kino, and explores man’s purpose as well as greed, defiance of societal norms, and evil. Steinbeck's inspiration was a Mexican folk tale from La Paz, Baja California Sur, Mexico, which he had heard in a visit to the formerly pearl-rich region in 1940. The book was adapted as a Mexican film named '' La Perla'' (1947) and as a cult Kannada movie '' Ondu Muttina Kathe'' (1987). The story is one of Steinbeck's most popular books and has been widely used in middle and high school classes. ''The Pearl'' is sometimes considered a parable. Plot Kino, a poor pearl fisherman, lives with his wife Juana and their infant son Coyotito in La Paz, Baja California Sur. Kino sees a scorpion crawl down one of the ropes holding up the hanging box that serves as Coyotito's crib and tries to remove it. However, Coyotito shakes the rope, causing the scorpion to fall into the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
John Steinbeck
John Ernst Steinbeck Jr. (; February 27, 1902 – December 20, 1968) was an American writer and the 1962 Nobel Prize in Literature winner "for his realistic and imaginative writings, combining as they do sympathetic humor and keen social perception." He has been called "a giant of American letters." During his writing career, he authored 33 books, with one book coauthored alongside Edward Ricketts, including 16 novels, six non-fiction books, and two collections of short stories. He is widely known for the comic novels ''Tortilla Flat'' (1935) and ''Cannery Row'' (1945), the multi-generation epic '' East of Eden'' (1952), and the novellas ''The Red Pony'' (1933) and ''Of Mice and Men'' (1937). The Pulitzer Prize–winning ''The Grapes of Wrath'' (1939) is considered Steinbeck's masterpiece and part of the American literary canon. In the first 75 years after it was published, it sold 14 million copies. Most of Steinbeck's work is set in central California, particularly in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Surface-supplied Diving
Surface-supplied diving is diving using equipment supplied with breathing gas using a diver's umbilical from the surface, either from the shore or from a diving support vessel, sometimes indirectly via a diving bell. This is different from scuba diving, where the diver's breathing equipment is completely self-contained and there is no link to the surface. The primary advantages of conventional surface supplied diving are lower risk of drowning and considerably larger breathing gas supply than scuba, allowing longer working periods and safer decompression. Disadvantages are the absolute limitation on diver mobility imposed by the length of the umbilical, encumbrance by the umbilical, and high logistical and equipment costs compared with scuba. The disadvantages restrict use of this mode of diving to applications where the diver operates within a small area, which is common in commercial diving work. The copper helmeted free-flow standard diving dress is the version which made com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monarchy Of Spain
, coatofarms = File:Coat_of_Arms_of_Spanish_Monarch.svg , coatofarms_article = Coat of arms of the King of Spain , image = Felipe_VI_in_2020_(cropped).jpg , incumbent = Felipe VI , incumbentsince = 19 June 2014 , his/her = His , heir_presumptive = Leonor, Princess of Asturias , first_monarch = Isabella I of Castile and Ferdinand II of Aragon ( Catholic Monarchs of Spain) , date = , appointer = Hereditary , residence = Royal Palace of Madrid (official)Palace of Zarzuela (private) , website The Spanish Monarchy The monarchy of Spain or Spanish monarchy ( es, Monarquía Española), constitutionally referred to as The Crown ( es, La Corona), is a constitutional institution and the highest office of Spain. The monarchy comprises the reigning monarch, his or her family, and the royal household organization which supports and facilitates the monarch in the exercise of his du ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rights
Rights are legal, social, or ethical principles of freedom or entitlement; that is, rights are the fundamental normative rules about what is allowed of people or owed to people according to some legal system, social convention, or ethical theory. Rights are of essential importance in such disciplines as law and ethics, especially theories of justice and deontology. Rights are fundamental to any civilization and the history of social conflicts is often bound up with attempts both to define and to redefine them. According to the ''Stanford Encyclopedia of Philosophy'', "rights structure the form of governments, the content of laws, and the shape of morality as it is currently perceived". Definitional issues One way to get an idea of the multiple understandings and senses of the term is to consider different ways it is used. Many diverse things are claimed as rights: There are likewise diverse possible ways to categorize rights, such as: There has been considerable debate a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hernán Cortés
Hernán Cortés de Monroy y Pizarro Altamirano, 1st Marquess of the Valley of Oaxaca (; ; 1485 – December 2, 1547) was a Spanish ''conquistador'' who led an expedition that caused the fall of the Aztec Empire and brought large portions of what is now mainland Mexico under the rule of the King of Castile in the early 16th century. Cortés was part of the generation of Spanish explorers and conquistadors who began the first phase of the Spanish colonization of the Americas. Born in Medellín, Spain, to a family of lesser nobility, Cortés chose to pursue adventure and riches in the New World. He went to Hispaniola and later to Cuba, where he received an '' encomienda'' (the right to the labor of certain subjects). For a short time, he served as '' alcalde'' (magistrate) of the second Spanish town founded on the island. In 1519, he was elected captain of the third expedition to the mainland, which he partly funded. His enmity with the Governor of Cuba, Diego Velázquez de Cu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pteria Sterna
''Pteria sterna'', or commonly known as the rainbow-lipped pearl oyster or the Pacific wing-oyster, is a species of marine bivalve mollusk in the family Pteriidae, the pearl oysters. This oyster can be found in shallow water along the tropical and subtropical Pacific coast of America, its range including Baja California, Mexico and northern Peru. History Fragments of shell ornaments made from the nacre of the Pacific wing-oyster have been found at ancient burial sites in Mexico, probably belonging to the indigenous Seri people of the Sonora region. This oyster has been the subject of a pearl fishery in the Gulf of California since before the arrival of Hernan Cortez in 1535; the Spaniards quickly appreciated the value of the harvest and in 1586 they declared the gathering of oysters to be a right of the Spanish crown. In 1874, compressed air diving equipment made harvesting the oysters easier. Over-exploitation caused populations of the oyster to become depleted and in 1940 the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Shrimp
Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are referred to as "shrimp". More narrow definitions may be restricted to Caridea, to smaller species of either group or to only the marine species. Under a broader definition, ''shrimp'' may be synonymous with prawn, covering stalk-eyed swimming crustaceans with long, narrow muscular tails (abdomens), long whiskers ( antennae), and slender legs. Any small crustacean which resembles a shrimp tends to be called one. They swim forward by paddling with swimmerets on the underside of their abdomens, although their escape response is typically repeated flicks with the tail driving them backwards very quickly. Crabs and lobsters have strong walking legs, whereas shrimp have thin, fragile legs which they use primarily for perching.Rudloe & Rudloe (2009 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Veliger
A veliger is the planktonic larva of many kinds of sea snails and freshwater snails, as well as most bivalve molluscs (clams) and tusk shells. Description The veliger is the characteristic larva of the gastropod, bivalve and scaphopod taxonomic classes. It is produced following either the embryonic or trochophore larval stage of development. In bivalves the veliger is sometimes referred to as a D-stage (early in its development) or pediveliger (late in its development) larva. This stage in the life history of these groups is a free-living planktonic organism; this mode of life potentially enhances dispersal to new regions far removed from the adult mollusks that produced the larvae. The general structure of the veliger includes a shell that surrounds the visceral organs of the larva (e.g., digestive tract, much of the nervous system, excretory organs) and a ciliated velum that extends beyond the shell as a single or multi-lobed structure used for swimming and particula ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spawn (biology)
Spawn is the Egg cell, eggs and Spermatozoa, sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of releasing the eggs and sperm, and the act of both sexes is called spawning. Most aquatic animals, except for aquatic mammals and marine reptile, reptiles, reproduce through the process of spawning. Spawn consists of the reproductive cells (gametes) of many aquatic animals, some of which will become fertilized and produce offspring. The process of spawning typically involves females releasing Ovum, ova (unfertilized eggs) into the water, often in large quantities, while males simultaneously or sequentially release spermatozoa (milt) to fertilize the eggs. Most fish reproduce by spawning, as do most other aquatic animals, including crustaceans such as crabs and shrimps, molluscs such as oysters and squid, echinoderms such as sea urchins and sea cucumbers, amphibians such as frogs and newts, aquatic insects such as mayflies and mos ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
