|
Eurycea Neotenes
''Eurycea neotenes'', also known as the Texas salamander, Bexar County salamander, Edwards Plateau salamander, or Texas neotenic salamander, is a species of entirely aquatic, lungless salamander native to the United States. It is endemic to central Texas, near Helotes, in Bexar County. Description The Texas salamander grows from in length. It is brown in color, often with yellow or brown mottling, with light-yellow spotting down its back. It is neotenic, with a slender body, short limbs, and bright-red external gills. The Texas salamander lives in caves, which resulted in reduced vision in its eyes, due to the long period of time in darkness. It is akin to the Texas blind salamander ''Eurycea rathbuni''. References * (2000): Phylogenetic relationships of central Texas hemidactyliine plethodontid salamanders, genus ''Eurycea'', and a taxonomic revision of the group. ''Herpetological Monographs'' 14: 1-80. * (2001): A new species of subterranean blind salamander (Plethodon ... [...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] |
Lungless Salamander
Plethodontidae, or lungless salamanders, are a family of salamanders. Most species are native to the Western Hemisphere, from British Columbia to Brazil, although a few species are found in Sardinia, Europe south of the Alps, and South Korea. In terms of number of species, they are by far the largest group of salamanders. Biology Adult lungless salamanders have four limbs, with four toes on the fore limbs, and usually with five on the hind limbs. Within many species, mating and reproduction occur solely on land. Accordingly, many species also lack an aquatic larval stage, a phenomenon known as direct development in which the offspring hatch as fully-formed, miniature adults. Direct development is correlated with changes in the developmental characteristics of plethodontids compared to other families of salamanders including increases in egg size and duration of embryonic development. Additionally, the evolutionary loss of the aquatic larval stage is related to a diminishing dep ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Endemic (ecology)
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsewhere. For example, the Cape sugarbird is found exclusively in southwestern South Africa and is therefore said to be ''endemic'' to that particular part of the world. An endemic species can be also be referred to as an ''endemism'' or in scientific literature as an ''endemite''. For example '' Cytisus aeolicus'' is an endemite of the Italian flora. '' Adzharia renschi'' was once believed to be an endemite of the Caucasus, but it was later discovered to be a non-indigenous species from South America belonging to a different genus. The extreme opposite of an endemic species is one with a cosmopolitan distribution, having a global or widespread range. A rare alternative term for a species that is endemic is "precinctive", which applies to s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Texas
Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by both List of U.S. states and territories by area, area (after Alaska) and List of U.S. states and territories by population, population (after California). Texas shares borders with the states of Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the west, and the Mexico, Mexican States of Mexico, states of Chihuahua (state), Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the south and southwest; and has a coastline with the Gulf of Mexico to the southeast. Houston is the List of cities in Texas by population, most populous city in Texas and the List of United States cities by population, fourth-largest in the U.S., while San Antonio is the second most pop ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Helotes, Texas
Helotes ( ) is a city in Bexar County, Texas, United States, located on the far northwest side of San Antonio. It is part of the San Antonio-New Braunfels metropolitan statistical area. Its population was 9,030 at the 2020 census. History According to anthropologists, the area was occupied seasonally from about 5,000 BCE by small bands of nomadic Native American tribes in search of food and game. The Lipan Apache moved into the area in the late 17th century and occupied it throughout the 18th century. However, the Lipan were forced from the area in the early 1820s by the Comanche Indians. A small farming and ranching community began to develop in the area shortly after the Texas Revolution in the late 1830s. The ranches suffered occasional attacks by the Comanches until the late 1870s. In 1858, a Scottish immigrant, Dr. George Marnoch, purchased the land that later became the site of the town. Marnoch's home at one time served as a stagecoach stop and a post office for c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bexar County, Texas
Bexar County ( or ; es, Béxar ) is a county in the U.S. state of Texas. It is in South Texas and its county seat is San Antonio. As of the 2020 census, the population was 2,009,324. Bexar County is included in the San Antonio–New Braunfels, TX metropolitan statistical area. It is the 16th-most populous county in the nation and the fourth-most populated in Texas. With a population that is 59.3% Hispanic as of 2020, it is Texas' most populous majority-Hispanic county and the third-largest such nationwide. History Bexar County was created on December 20, 1836, and encompassed almost the entire western portion of the Republic of Texas. This included the disputed areas of eastern New Mexico northward to Wyoming. After statehood, 128 counties were carved out of its area. The county was named for San Antonio de Béxar, one of the 23 Mexican municipalities (administrative divisions) of Texas at the time of its independence. San Antonio de Béxar—originally ''Villa de San ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Neoteny
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] |
Gill
A gill () is a respiratory organ that many aquatic organisms use to extract dissolved oxygen from water and to excrete carbon dioxide. The gills of some species, such as hermit crabs, have adapted to allow respiration on land provided they are kept moist. The microscopic structure of a gill presents a large surface area to the external environment. Branchia (pl. branchiae) is the zoologists' name for gills (from Ancient Greek ). With the exception of some aquatic insects, the filaments and lamellae (folds) contain blood or coelomic fluid, from which gases are exchanged through the thin walls. The blood carries oxygen to other parts of the body. Carbon dioxide passes from the blood through the thin gill tissue into the water. Gills or gill-like organs, located in different parts of the body, are found in various groups of aquatic animals, including mollusks, crustaceans, insects, fish, and amphibians. Semiterrestrial marine animals such as crabs and mudskippers have gill cham ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Caves
A cave or cavern is a natural void in the ground, specifically a space large enough for a human to enter. Caves often form by the weathering of rock and often extend deep underground. The word ''cave'' can refer to smaller openings such as sea caves, rock shelters, and grottos, that extend a relatively short distance into the rock and they are called ''exogene'' caves. Caves which extend further underground than the opening is wide are called ''endogene'' caves. Speleology is the science of exploration and study of all aspects of caves and the cave environment. Visiting or exploring caves for recreation may be called ''caving'', ''potholing'', or ''spelunking''. Formation types The formation and development of caves is known as ''speleogenesis''; it can occur over the course of millions of years. Caves can range widely in size, and are formed by various geological processes. These may involve a combination of chemical processes, erosion by water, tectonic forces, microorgani ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eyes
Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light and convert it into electro-chemical impulses in neurons (neurones). In higher organisms, the eye is a complex optical system which collects light from the surrounding environment, regulates its intensity through a diaphragm, focuses it through an adjustable assembly of lenses to form an image, converts this image into a set of electrical signals, and transmits these signals to the brain through complex neural pathways that connect the eye via the optic nerve to the visual cortex and other areas of the brain. Eyes with resolving power have come in ten fundamentally different forms, and 96% of animal species possess a complex optical system. Image-resolving eyes are present in molluscs, chordates and arthropods. The most simple eyes, pit eyes, ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurycea Rathbuni
The Texas blind salamander (''Eurycea rathbuni'') is a rare cave-dwelling troglobite amphibian native to San Marcos, Hays County, Texas, specifically the San Marcos Pool of the Edwards Aquifer. Description The species has a broad, flat, snout and head, and vestigial eyes beneath that are covered by skin. Like other neotenous salamanders, it has external gills for absorbing oxygen from the water. The salamander's mature length is around . The forelimbs carry four digits and the hind limbs possess five digits. Its diet varies by what flows into its cave, and includes blind shrimp (''Palaemonetes antrorum''), snails, and amphipods. Distribution and habitat Specimens have been collected at seven localities in the Purgatory Creek system and along the San Marcos Fault near San Marcos, Texas. Adults and immature larvae are well-adapted for living in underground streams in caves, and many probably inhabit deep recesses that are not accessible to collectors. Specimens have been tak ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
.jpg "Click for more on -> Endemic (ecology)")
