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Amblystoma
The mole salamanders ( genus ''Ambystoma'') are a group of advanced salamanders endemic to North America. The group has become famous due to the presence of the axolotl (''A. mexicanum''), widely used in research due to its paedomorphosis, and the tiger salamander (''A. tigrinum, A. mavortium'') which is the official amphibian of many states, and often sold as a pet. General description Terrestrial mole salamanders are identified by having wide, protruding eyes, prominent costal grooves, and thick arms. Most have vivid patterning on dark backgrounds, with marks ranging from deep blue spots to large yellow bars depending on the species. Terrestrial adults spend most of their lives underground in burrows, either of their own making or abandoned by other animals. Some northern species may hibernate in these burrows throughout the winter. They live alone and feed on any available invertebrate. Adults spend little time in the water, only returning to the ponds of their birth ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spotted Salamander
The spotted salamander or yellow-spotted salamander (''Ambystoma maculatum'') is a mole salamander common in eastern United States and Canada. The spotted salamander is the state amphibian of Ohio and South Carolina. This salamander ranges from Nova Scotia, to Lake Superior, to southern Georgia and Texas. Its embryos have been found to have symbiotic algae living in and around them, the only known example of vertebrate cells hosting an endosymbiont microbe (unless mitochondria are considered). Description The spotted salamander is about long. They are stout, like most mole salamanders, and have wide snouts. The spotted salamander's main color is black, but can sometimes be a blueish-black, dark gray, dark green, or even dark brown. Two uneven rows of yellowish-orange spots run from the top of the head (near the eyes) to the tip of the tail. The spotted salamander's spots near the top of its head are more orange, while the spots on the rest of its body are more yellow. The under ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caudal (anatomical Term)
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek language, Greek roots, describe something in its standard anatomical position. This position provides a definition of what is at the front ("anterior"), behind ("posterior") and so on. As part of defining and describing terms, the body is described through the use of anatomical planes and anatomical axis, anatomical axes. The meaning of terms that are used can change depending on whether an organism is bipedal or quadrupedal. Additionally, for some animals such as invertebrates, some terms may not have any meaning at all; for example, an animal that is radially symmetrical will have no anterior surface, but can still have a description that a part is close to the middle ("proximal") or further from the middle ("distal"). International organisations have determined vocabularies that are often used as standard vocabular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ploidy
Ploidy () is the number of complete sets of chromosomes in a cell (biology), cell, and hence the number of possible alleles for Autosome, autosomal and Pseudoautosomal region, pseudoautosomal genes. Sets of chromosomes refer to the number of maternal and paternal chromosome copies, respectively, in each homologous chromosome pair, which chromosomes naturally exist as. Somatic cells, Tissue (biology), tissues, and Individual#Biology, individual organisms can be described according to the number of sets of chromosomes present (the "ploidy level"): monoploid (1 set), diploid (2 sets), triploid (3 sets), tetraploid (4 sets), pentaploid (5 sets), hexaploid (6 sets), heptaploid or septaploid (7 sets), etc. The generic term polyploidy, polyploid is often used to describe cells with three or more chromosome sets. Virtually all sexual reproduction, sexually reproducing organisms are made up of somatic cells that are diploid or greater, but ploidy level may vary widely between different or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parthenogenesis
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development of embryos occur in a gamete (egg or sperm) without combining with another gamete (e.g., egg and sperm fusing). In animals, parthenogenesis means development of an embryo from an unfertilized Gametophyte, egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg. Parthenogenesis occurs naturally in some plants, algae, invertebrate animal species (including nematodes, some tardigrades, water fleas, some scorpions, aphids, some mites, some bees, some Phasmatodea and parasitic wasps) and a few vertebrates (such as some fish, amphibians, reptiles and birds). This type of reproduction has been induced artificially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gynogenesis
Gynogenesis, a form of parthenogenesis, is a system of asexual reproduction that requires the presence of sperm without the actual contribution of its DNA for completion. The paternal DNA dissolves or is destroyed before it can fuse with the egg. The egg cell of the organism is able to develop, unfertilized, into an adult using only maternal genetic material. Gynogenesis is often termed "sperm parasitism" in reference to the somewhat pointless role of male gametes. Gynogenetic species, "gynogens" for short, are unisexual, meaning they must mate with males from a closely related bisexual species that normally reproduces sexually. Gynogenesis is a disadvantageous mating system for males, as they are unable to pass on their DNA. The question as to why this reproductive mode exists, given that it appears to combine the disadvantages of both asexual and sexual reproduction, remains unsolved in the field of evolutionary biology. The male equivalent to this process is Androgenesis where th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plateau Tiger Salamander
The plateau tiger salamander or Mexican tiger salamander (''Ambystoma velasci'') is a species of mole salamander in the family Ambystomatidae. It is typically considered endemic to Mexico, although its range might extend to the United States. Its natural habitat is grassland, including sparse forest and semiarid grassland. Breeding takes place in a range of aquatic habitats: deep volcanic lakes, shallow vernal pools, artificial cattle ponds, and intermittent, fish-free stream pools. It exhibits facultative paedomorphosis. ''Ambystoma velasci'' is locally threatened by habitat loss due to urbanization, forest clearance, and water extraction, and also by pollution and the introduction of fish and frogs (''Lithobates catesbeianus The American bullfrog (''Lithobates catesbeianus''), often simply known as the bullfrog in Canada and the United States, is a large true frog native to eastern North America. It typically inhabits large permanent water bodies such as swamps, po ...''). ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
California Tiger Salamander
The California tiger salamander (''Ambystoma californiense'') is a vulnerable amphibian native to California. It is a mole salamander. Previously considered to be a subspecies of the tiger salamander (''A. tigrinum)'', the California tiger salamander was recently designated a separate species again. The California tiger salamander distinct population segment (DPS) in Sonoma County and the Santa Barbara County DPS are listed as federally endangered, while the Central California DPS is listed as federally threatened. The Sonoma County, south San Joaquin, and the Santa Barbara County DPS have diverged from the rest of the California tiger salamander populations for over one million years, since the Pleistocene and they may warrant status as separate species. Description The California tiger salamander is a relatively large, secretive amphibian endemic to California. Adults can grow to a total length of about 7–8 inches. It has a stocky body and a broad, rounded snout. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barred Tiger Salamander
The barred tiger salamander or western tiger salamander (''Ambystoma mavortium'') is a species of mole salamander that lives in lower western Canada, the western United States and northern Mexico. Description The barred tiger salamander typically grows from but it can grow to long at the most and is one of the largest species of salamander in North America. It has a broad head and a sturdy body. The color is variable across its range. The dorsal surface is grey, dark brown or black with bars and spots of muddy yellow giving it a tiger-like coloring. The ventral surface varies from light to dark. Larvae have alternating dark and light blotches on the centre of the dorsal surface and pale stripes running along the sides. Behavior Primarily nocturnal, barred tiger salamanders are opportunistic feeders, and will often eat anything they can catch, including various insects, slugs, and earthworms. They are primarily terrestrial as adults, but their juvenile, larval stage is entirely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Range (biology)
Species distribution —or species dispersion — is the manner in which a biological taxon is spatially arranged. The geographic limits of a particular taxon's distribution is its range, often represented as shaded areas on a map. Patterns of distribution change depending on the scale at which they are viewed, from the arrangement of individuals within a small family unit, to patterns within a population, or the distribution of the entire species as a whole (range). Species distribution is not to be confused with dispersal, which is the movement of individuals away from their region of origin or from a population center of high density. Range In biology, the range of a species is the geographical area within which that species can be found. Within that range, distribution is the general structure of the species population, while dispersion is the variation in its population density. Range is often described with the following qualities: * Sometimes a distinction is made betw ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neotenic
Neoteny (), also called juvenilization,Montagu, A. (1989). Growing Young. Bergin & Garvey: CT. is the delaying or slowing of the physiological, or somatic, development of an organism, typically an animal. Neoteny is found in modern humans compared to other primates. In progenesis or paedogenesis, sexual development is accelerated. Both neoteny and progenesis result in paedomorphism (as having the form typical of children) or paedomorphosis (changing towards forms typical of children), a type of heterochrony. It is the retention in adults of traits previously seen only in the young. Such retention is important in evolutionary biology, domestication and evolutionary developmental biology. Some authors define paedomorphism as the retention of larval traits, as seen in salamanders.Schell, S. C. ''Handbook of Trematodes of North America North of Mexico'', 1985, pg. 22 History and etymology The origins of the concept of neoteny have been traced to the Bible (as argued by Ashley Monta ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barred Tiger Salamander Tennoji
Barring may refer to: * Barring (music), a guitar playing technique * Barring engine, forms part of the installation of a large stationary steam engine * Barring order, an order used by a court to protect a person, object, business, company, state, country, establishment, or entity, and the general public, in a situation involving alleged domestic violence, child abuse, assault, harassment, stalking, or sexual assault. See also * Bar (other) Bar or BAR may refer to: Food and drink * Bar (establishment), selling alcoholic beverages * Candy bar * Chocolate bar Science and technology * Bar (river morphology), a deposit of sediment * Bar (tropical cyclone), a layer of cloud * Bar (u ... * Banning {{disambiguation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroxine
File:Thyroid_system.svg, upright=1.5, The thyroid system of the thyroid hormones T3 and T4 rect 376 268 820 433 Thyroid-stimulating hormone rect 411 200 849 266 Thyrotropin-releasing hormone rect 297 168 502 200 Hypothalamus rect 66 216 386 256 Anterior pituitary gland rect 66 332 342 374 Negative feedback rect 308 436 510 475 Thyroid gland rect 256 539 563 635 Thyroid hormones rect 357 827 569 856 Catecholamine rect 399 716 591 750 Metabolism desc bottom-left Thyroid hormones are any hormones produced and released by the thyroid gland, namely triiodothyronine (T3) and thyroxine (T4). They are tyrosine-based hormones that are primarily responsible for regulation of metabolism. T3 and T4 are partially composed of iodine. A deficiency of iodine leads to decreased production of T3 and T4, enlarges the thyroid tissue and will cause the disease known as simple goitre. The major form of thyroid hormone in the blood is thyroxine (T4), whose half-life of around one week is longer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
