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Atelopus Varius
''Atelopus varius'', the Costa Rican variable harlequin toad or clown frog, is a small Neotropical true toad from the family Bufonidae (Crump 1986). Once ranging from Costa Rica to Panama, ''A. varius'' is now listed as critically endangered and has been reduced to a single remnant population near Quepos, Costa Rica (rediscovered in 2003) and has only relict populations in western Panama (IUCN). Recent variation in air temperature, precipitation, stream flow patterns, and the subsequent spread of a pathogenic chytrid fungus ''(Batrachochytrium dendrobatidis)'' linked to global climate change have been the leading cause of decline for ''A. varius'' (Lips et al. 2003 and Pounds et al. 2006). '' A. zeteki'' has been considered a subspecies of ''A. varius'', but is now generally considered a separate species (Savage, 2002). Geographic range The historic range of A. varius stretched from the Pacific and Atlantic slopes of the Cordilleras de Tilaran mountain range in Costa Rica ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hinrich Lichtenstein
Martin Hinrich Carl Lichtenstein (10 January 1780 – 2 September 1857) was a German physician, explorer, botanist and zoologist. Biography Born in Hamburg, Lichtenstein was the son of Anton August Heinrich Lichtenstein. He studied medicine at Jena and Helmstedt. Between 1802 and 1806 he travelled in southern Africa, becoming the personal physician of the Governor of the Cape of Good Hope. In 1811 he published ''Reisen im südlichen Afrika : in den Jahren 1803, 1804, 1805, und 1806''; as a result, he was appointed professor of zoology at the University of Berlin in 1811, and appointed director of the Berlin Zoological Museum in 1813. In 1829, he was elected a foreign member of the Royal Swedish Academy of Sciences. He died after he had a stroke at sea travelling aboard a steamer from Korsør to Kiel. Legacy Lichtenstein was responsible for the creation of Berlin's Zoological Gardens in 1841, when he persuaded King Frederick William IV of Prussia to donate the grounds of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tetrodotoxin
Tetrodotoxin (TTX) is a potent neurotoxin. Its name derives from Tetraodontiformes, an order that includes pufferfish, porcupinefish, ocean sunfish, and triggerfish; several of these species carry the toxin. Although tetrodotoxin was discovered in these fish and found in several other animals (e.g., in blue-ringed octopuses, rough-skinned newts, and moon snails), it is actually produced by certain infecting or symbiotic bacteria like ''Pseudoalteromonas'', '' Pseudomonas'', and '' Vibrio'' as well as other species found in animals. Tetrodotoxin is a sodium channel blocker. It inhibits the firing of action potentials in neurons by binding to the voltage-gated sodium channels in nerve cell membranes and blocking the passage of sodium ions (responsible for the rising phase of an action potential) into the neuron. This prevents the nervous system from carrying messages and thus muscles from contracting in response to nervous stimulation. Its mechanism of action, selective blo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Osmoregulation
Osmoregulation is the active regulation of the osmotic pressure of an organism's body fluids, detected by osmoreceptors, to maintain the homeostasis of the organism's water content; that is, it maintains the fluid balance and the concentration of electrolytes ( salts in solution which in this case is represented by body fluid) to keep the body fluids from becoming too diluted or concentrated. Osmotic pressure is a measure of the tendency of water to move into one solution from another by osmosis. The higher the osmotic pressure of a solution, the more water tends to move into it. Pressure must be exerted on the hypertonic side of a selectively permeable membrane to prevent diffusion of water by osmosis from the side containing pure water. Although there may be hourly and daily variations in osmotic balance, an animal is generally in an osmotic steady state over the long term. Organisms in aquatic and terrestrial environments must maintain the right concentration of solutes and am ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cutaneous Respiration
Cutaneous respiration, or cutaneous gas exchange (sometimes called, skin breathing), is a form of respiration in which gas exchange occurs across the skin or outer integument of an organism rather than gills or lungs. Cutaneous respiration may be the sole method of gas exchange, or may accompany other forms, such as ventilation. Cutaneous respiration occurs in a wide variety of organisms, including insects, amphibians, fish, sea snakes, turtles, and to a lesser extent in mammals. Physical constraints Gas exchange in cutaneous respiration is controlled by three factors: * Ventilation: the rate of delivery of respiratory medium (water or air) to the respiratory surface *Diffusion: the passage of gases through the skin *Convection: the carrying of dissolved gases towards or away from the lungs Taxonomic diversity in chordates Fish Cutaneous respiration occurs in a variety of marine, intertidal, and freshwater fish. For aquatic respiration, fish respire primarily via gills but c ... [...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] |
Chytrid Fungus
Chytridiomycota are a division of zoosporic organisms in the kingdom Fungi, informally known as chytrids. The name is derived from the Ancient Greek ('), meaning "little pot", describing the structure containing unreleased zoöspores. Chytrids are one of the early diverging fungal lineages, and their membership in kingdom Fungi is demonstrated with chitin cell walls, a posterior whiplash flagellum, absorptive nutrition, use of glycogen as an energy storage compound, and synthesis of lysine by the -amino adipic acid (AAA) pathway. Chytrids are saprobic, degrading refractory materials such as chitin and keratin, and sometimes act as parasites. There has been a significant increase in the research of chytrids since the discovery of ''Batrachochytrium dendrobatidis'', the causal agent of chytridiomycosis. Classification Species of Chytridiomycota have traditionally been delineated and classified based on development, morphology, substrate, and method of zoöspore discharge. Howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pathogenic
In biology, a pathogen ( el, πάθος, "suffering", "passion" and , "producer of") in the oldest and broadest sense, is any organism or agent that can produce disease. A pathogen may also be referred to as an infectious agent, or simply a germ. The term ''pathogen'' came into use in the 1880s. Typically, the term ''pathogen'' is used to describe an ''infectious'' microorganism or agent, such as a virus, bacterium, protozoan, prion, viroid, or fungus. Small animals, such as helminths and insects, can also cause or transmit disease. However, these animals are usually referred to as parasites rather than pathogens. The scientific study of microscopic organisms, including microscopic pathogenic organisms, is called microbiology, while parasitology refers to the scientific study of parasites and the organisms that host them. There are several pathways through which pathogens can invade a host. The principal pathways have different episodic time frames, but soil has the longest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Decline In Amphibian Populations
Since the 1980s, decreases in amphibian populations, including population decline and localized mass extinctions, have been observed in locations all over the world. These declines are known as one of the most critical threats to global biodiversity. Recent (2007) research indicates the reemergence of varieties of chytrid fungi may account for a substantial fraction of the overall decline. A more recent (2018) paper published in ''Science'' confirms this. Several secondary causes may be involved, including other diseases, habitat destruction and modification, exploitation, pollution, pesticide use, introduced species, and ultraviolet-B radiation (UV-B). However, many of the causes of amphibian declines are still poorly understood, and the topic is currently a subject of much ongoing research. Calculations based on extinction rates suggest that the current extinction rate of amphibians could be 211 times greater than the background extinction rate and the estimate goes up to 25,0 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amphibian
Amphibians are four-limbed and ectothermic vertebrates of the class Amphibia. All living amphibians belong to the group Lissamphibia. They inhabit a wide variety of habitats, with most species living within terrestrial, fossorial, arboreal or freshwater aquatic ecosystems. Thus amphibians typically start out as larvae living in water, but some species have developed behavioural adaptations to bypass this. The young generally undergo metamorphosis from larva with gills to an adult air-breathing form with lungs. Amphibians use their skin as a secondary respiratory surface and some small terrestrial salamanders and frogs lack lungs and rely entirely on their skin. They are superficially similar to reptiles like lizards but, along with mammals and birds, reptiles are amniotes and do not require water bodies in which to breed. With their complex reproductive needs and permeable skins, amphibians are often ecological indicators; in recent decades there has been a dramatic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lizard
Lizards are a widespread group of squamate reptiles, with over 7,000 species, ranging across all continents except Antarctica, as well as most oceanic island chains. The group is paraphyletic since it excludes the snakes and Amphisbaenia although some lizards are more closely related to these two excluded groups than they are to other lizards. Lizards range in size from chameleons and geckos a few centimeters long to the 3-meter-long Komodo dragon. Most lizards are quadrupedal, running with a strong side-to-side motion. Some lineages (known as " legless lizards"), have secondarily lost their legs, and have long snake-like bodies. Some such as the forest-dwelling ''Draco'' lizards are able to glide. They are often territorial, the males fighting off other males and signalling, often with bright colours, to attract mates and to intimidate rivals. Lizards are mainly carnivorous, often being sit-and-wait predators; many smaller species eat insects, while the Komodo eats mammals as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Monteverde
Monteverde is the twelfth canton of the Puntarenas province of Costa Rica. It is located in the Cordillera de Tilarán mountain range. Roughly a four-hour drive from the Central Valley, Monteverde is one of the country's major ecotourism destinations. The area is host to the Monteverde Cloud Forest Reserve and several other natural attractions, which draw considerable numbers of tourists and naturalists. National Geographic has called the Monteverde Cloud Forest Biological Reserve "the jewel in the crown of cloud forest reserves". Newsweek has declared Monteverde the world's #14 "Place to Remember Before it Disappears". By popular vote in Costa Rica, Monteverde was deemed one of the ''Seven Natural Wonders of Costa Rica'', along with Isla del Coco, Volcán Arenal, Cerro Chirripó, Río Celeste, Tortuguero, and Volcán Poás. Santa Elena is the head town. Its homes and businesses serve as the region's tourist hub, along with the nearby neighborhood of Cerro Plano, the co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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