Mount Magazine named Magazine Mountain, is the highest point of the U. S. Interior Highlands and the U. S. state of Arkansas, is the site of Mount Magazine State Park. It is a flat-topped mesa capped by hard rock and rimmed by precipitous cliffs. There are two summits atop the mountain: Signal Hill, which reaches 2,753 feet, Mossback Ridge, which reaches 2,700 ft. Mount Magazine gets its name from French explorers who, while traveling through the area, witnessed a landslide on the mountain; the noise from the landslide was so great that one explorer described it as the sound of an ammunition magazine exploding, hence the name "Magazine". The U. S. Geological Survey's Geographic Names Information System indicates that the official name of this landform is "Magazine Mountain", not "Mount Magazine". "Mount " is used for peaks and " Mountain" is used for ridges, which better describes this landform. Mount Magazine appears in the GNIS as a ridge with Signal Hill as its summit. "Mount Magazine" is the name used by the Arkansas Department of Parks and Tourism, which follows what the locals have used since the area was first settled.
Mount Magazine is called "the highest point between the Alleghenies and the Rockies", but there are many parts of Texas, Kansas, South Dakota, North Dakota with higher elevations. Mount Magazine is located due north of Blue Mountain Lake in Logan County, Arkansas 45 mi east of the Arkansas-Oklahoma border; the most scenic route to the top is a 10 mi drive along Highway 309 from Havana. Many consider Mount Magazine to be part of the Ouachita Mountains, though it is part of the Arkansas River Valley, it lies within a southern extension of the Ozark National Forest despite being much closer to the Ouachita National Forest. As the South American plate collided with the North American plate during the late Paleozoic, a major foreland basin, the Arkoma Basin, developed north of the Ouachita Mountains. Small grains of sediment that had filled the Arkoma Basin were compacted and cemented into sedimentary rock; as the land rose above sea level, small streams developed that merged into the Arkansas River.
After millions of years of erosion, synclines like Mount Magazine have become the most positive topographic features. Mount Magazine is a broad mesa composed of Pennsylvanian sedimentary rocks deposited in various shallow-water environments. Like many mountains in the western Arkansas River Valley, Mount Magazine is capped by the Savanna Formation, a sequence of shale and sandstone; the Savanna Formation is conformable with the underlying McAlester Formation, a sequence of shale, sandstone, a number of coal beds. The McAlester Formation is conformable with the underlying Hartshorne Sandstone, a prominent ledge-former under favorable structural conditions; the Hartshorne Sandstone is unconformable with the underlying Atoka Formation. This unit has the largest areal extent of any of the Paleozoic formations in Arkansas, extending as far north as the Boston Mountains, is divided into upper and lower members. List of mountains of Arkansas List of U. S. states by elevation Media related to Mount Magazine at Wikimedia Commons
The Paleozoic Era is the earliest of three geologic eras of the Phanerozoic Eon. It is the longest of the Phanerozoic eras, lasting from 541 to 251.902 million years ago, is subdivided into six geologic periods: the Cambrian, Silurian, Devonian and Permian. The Paleozoic comes after the Neoproterozoic Era of the Proterozoic Eon and is followed by the Mesozoic Era; the Paleozoic was a time of dramatic geological and evolutionary change. The Cambrian witnessed the most rapid and widespread diversification of life in Earth's history, known as the Cambrian explosion, in which most modern phyla first appeared. Arthropods, fish, amphibians and diapsids all evolved during the Paleozoic. Life began in the ocean but transitioned onto land, by the late Paleozoic, it was dominated by various forms of organisms. Great forests of primitive plants covered the continents, many of which formed the coal beds of Europe and eastern North America. Towards the end of the era, sophisticated diapsids and synapsids were dominant and the first modern plants appeared.
The Paleozoic Era ended with the largest extinction event in the history of Earth, the Permian–Triassic extinction event. The effects of this catastrophe were so devastating that it took life on land 30 million years into the Mesozoic Era to recover. Recovery of life in the sea may have been much faster; the Paleozoic era began and ended with supercontinents and in between were the rise of mountains along the continental margins, flooding and draining of shallow seas between the mountain ranges, in the interior of the continents. At its start, the supercontinent Pannotia broke up. Paleoclimatic studies and evidence of glaciers indicate that central Africa was most in the polar regions during the early Paleozoic. During the early Paleozoic, the huge continent Gondwana was forming. By mid-Paleozoic, the collision of North America and Europe produced the Acadian-Caledonian uplifts, a subduction plate uplifted eastern Australia. By the late Paleozoic, continental collisions formed the supercontinent of Pangaea and resulted in some of the great mountain chains, including the Appalachians, Ural Mountains, mountains of Tasmania.
There are six periods in the Paleozoic Era: Cambrian, Silurian, Devonian and the Permian. The Cambrian spans from 541 million years to 485 million years and is the first period of the Paleozoic era of the Phanerozoic; the Cambrian marked a boom in evolution in an event known as the Cambrian explosion in which the largest number of creatures evolved in any single period of the history of the Earth. Creatures like algae evolved, but the most ubiquitous of that period were the armored arthropods, like trilobites. All marine phyla evolved in this period. During this time, the supercontinent Pannotia begins to break up, most of which became the supercontinent Gondwana; the Ordovician spanned from 485 million years to 443 million years ago. The Ordovician was a time in Earth's history in which many of the biological classes still prevalent today evolved, such as primitive fish and coral; the most common forms of life, were trilobites and shellfish. More the first arthropods went ashore to colonize the empty continent of Gondwana.
By the end of the Ordovician, Gondwana was at the south pole, early North America had collided with Europe, closing the Atlantic Ocean. Glaciation of Africa resulted in a major drop in sea level, killing off all life that had established along coastal Gondwana. Glaciation may have caused the Ordovician–Silurian extinction events, in which 60% of marine invertebrates and 25% of families became extinct, is considered the first mass extinction event and the second deadliest; the Silurian spanned from 443 to 416 million years ago. The Silurian saw the rejuvenation of life; this period saw the mass evolution of fish, as jawless fish became more numerous, jawed fish evolved, the first freshwater fish evolved, though arthropods, such as sea scorpions, were still apex predators. Terrestrial life evolved, including early arachnids and centipedes; the evolution of vascular plants allowed plants to gain a foothold on land. These early plants were the forerunners of all plant life on land. During this time, there were four continents: Gondwana, Laurentia and Avalonia.
The recent rise in sea levels allowed many new species to thrive in water. The Devonian spanned from 416 million years to 359 million years ago. Known as "The Age of the Fish", the Devonian featured a huge diversification of fish, including armored fish like Dunkleosteus and lobe-finned fish which evolved into the first tetrapods. On land, plant groups diversified in an event known as the Devonian Explosion when plants made lignin allowing taller growth and vascular tissue: the first trees evolved, as well as seeds; this event diversified arthropod life, by providing them new habitats. The first amphibians evolved, the fish were now at the top of the food chain. Near the end of the Devonian, 70% of all species became extinct in an event known as the Late Devonian extinction, the Earth's second mass extinction event; the Carboniferous spanned from 359 million to 299 million years ago. During this time, average global temperatures were exc
The white-tailed deer known as the whitetail or Virginia deer, is a medium-sized deer native to the United States, Mexico, Central America, South America as far south as Peru and Bolivia. It has been introduced to New Zealand, Jamaica, Puerto Rico, the Bahamas, the Lesser Antilles, some countries in Europe, such as Finland, the Czech Republic and Serbia. In the Americas, it is the most distributed wild ungulate. In North America, the species is distributed east of the Rocky Mountains as well as in most of Mexico, aside from Lower California, in southwestern Arizona. IIt is replaced by the black-tailed or mule deer from that point west. However, it is found in mixed deciduous riparian corridors, river valley bottomlands, lower foothills of the northern Rocky Mountain region from South Dakota west to eastern Washington and eastern Oregon and north to northeastern British Columbia and southern Yukon, including in the Montana Valley and Foothill grasslands; the conversion of land adjacent to the Canadian Rockies into agriculture use and partial clear-cutting of coniferous trees has been favorable to the white-tailed deer and has pushed its distribution to as far north as Yukon.
Populations of deer around the Great Lakes have expanded their range northwards, due to conversion of land to agricultural uses favoring more deciduous vegetation, local caribou and moose populations. The westernmost population of the species, known as the Columbian white-tailed deer, once was widespread in the mixed forests along the Willamette and Cowlitz River valleys of western Oregon and southwestern Washington, but today its numbers have been reduced, it is classified as near-threatened; this population is separated from other white-tailed deer populations. Some taxonomists have attempted to separate white-tailed deer into a host of subspecies, based on morphological differences. Genetic studies, suggest fewer subspecies within the animal's range, as compared to the 30 to 40 subspecies that some scientists described in the last century; the Florida Key deer, O. v. clavium, the Columbian white-tailed deer, O. v. leucurus, are both listed as endangered under the U. S. Endangered Species Act.
In the United States, the Virginia white-tail, O. v. virginianus, is among the most widespread subspecies. The white-tailed deer species has tremendous genetic variation and is adaptable to several environments. Several local deer populations in the southern states, are descended from white-tailed deer transplanted from various localities east of the Continental Divide; some of these deer populations may have been from as far north as the Great Lakes region to as far west as Texas, yet are quite at home in the Appalachian and Piedmont regions of the south. These deer, over time, have intermixed with the local indigenous deer populations. Central and South America have a complex number of white-tailed deer subspecies that range from Guatemala to as far south as Peru; this list of subspecies of deer is more exhaustive than the list of North American subspecies, the number of subspecies is questionable. However, the white-tailed deer populations in these areas are difficult to study, due to overhunting in many parts and a lack of protection.
Some areas no longer carry deer, so assessing the genetic difference of these animals is difficult. Some subspecies names, ordered alphabetically: O. v. acapulcensis – Acapulco white-tailed deer O. v. borealis – northern white-tailed deer O. v. carminis – Carmen Mountains white-tailed deer O. v. clavium – Key deer or Florida Keys white-tailed deer O. v. chiriquensis – Chiriqui white-tailed deer O. v. couesi – Coues' white-tailed deer, Arizona white-tailed deer, or fantail deer O. v. dakotensis – Dakota white-tailed deer or northern plains white-tailed deer O. v. hiltonensis – Hilton Head Island white-tailed deer O. v. idahoensis – white-tailed deer O. v. leucurus – Columbian white-tailed deer O. v. macrourus – Kansas white-tailed deer O. v. mcilhennyi – Avery Island white-tailed deer O. v. mexicanus – Mexican white-tailed deer O. v. miquihuanensis – Miquihuan white-tailed deer O. v. nelsoni – Chiapas white-tailed deer O. v. nigribarbis – Blackbeard Island white-tailed deer O. v. oaxacensis – Oaxaca white-tailed deer O. v. ochrourus – northwestern white-tailed deer or northern Rocky Mountains white-tailed deer O. v. osceola – Florida coastal white-tailed deer O. v. rothschildi – Coiba Island white-tailed deer O. v. seminolus – Florida white-tailed deer O. v. sinaloae – Sinaloa white-tailed deer O. v. taurinsulae – Bulls Island white-tailed deer O. v. texanus – Texas white-tailed deer O. v. thomasi – Mexican lowland white-tailed deer O. v. toltecus – rain forest white-tailed deer O. v. truei – Central American white-tailed deer O. v. venatorius – Hunting Island white-tailed deer O. v. veraecrucis – northern Veracruz white-tailed deer O. v. virginianus – Virginia white-tailed deer or southern white-tailed deer O. v. yucatanensis – Yucatán white-tailed deer O. v. cariacou – O. v. curassavicus
American black bear
The American black bear is a medium-sized bear native to North America. It is the continent's smallest and most distributed bear species. American black bears are omnivores, with their diets varying depending on season and location, they live in forested areas, but do leave forests in search of food. Sometimes they become attracted to human communities because of the immediate availability of food; the American black bear is the world's most common bear species. It is listed by the International Union for Conservation of Nature as a least-concern species, due to its widespread distribution and a large population estimated to be twice that of all other bear species combined. Along with the brown bear, it is one of only two of the eight modern bear species not considered by the IUCN to be globally threatened with extinction. American black bears mark trees using their teeth and claws as a form of communication with other bears, a behavior common to many species of bears. Despite living in North America, American black bears are not related to brown bears and polar bears.
American and Asian black bears are considered sister taxa and are more related to each other than to the other modern species of bears. According to recent studies, the sun bear is a recent split from this lineage. A small primitive bear called Ursus abstrusus is the oldest known North American fossil member of the genus Ursus, dated to 4.95 mya. This suggests that U. abstrusus may be the direct ancestor of the American black bear, which evolved in North America. Although Wolverton and Lyman still consider U. vitabilis an "apparent precursor to modern black bears", it has been placed within U. americanus. The ancestors of American black bears and Asian black bears diverged from sun bears 4.58 mya. The American black bear split from the Asian black bear 4.08 mya. The earliest American black bear fossils, which were located in Port Kennedy, Pennsylvania resemble the Asian species, though specimens grew to sizes comparable to grizzly bears. From the Holocene to the present, American black bears seem to have shrunk in size, but this has been disputed because of problems with dating these fossil specimens.
The American black bear lived during the same period as the giant and lesser short-faced bears and the Florida spectacled bear. These tremarctine bears evolved from bears -- 8 ma; the giant and lesser short-faced bears are thought to have been carnivorous and the Florida spectacled bear more herbivorous, while the American black bears remained arboreal omnivores, like their Asian ancestors. The American black bear's generalist behavior allowed it to exploit a wider variety of foods and has been given as a reason why, of these three genera, it alone survived climate and vegetative changes through the last Ice Age while the other, more specialized North American predators became extinct. However, both Arctodus and Tremarctos had survived several previous ice ages. After these prehistoric ursids became extinct during the last glacial period 10,000 years ago, American black bears were the only bear present in much of North America until the migration of brown bears to the rest of the continent.
American black bears are reproductively compatible with several other bear species and have produced hybrid offspring. According to Jack Hanna's Monkeys on the Interstate, a bear captured in Sanford, was thought to have been the offspring of an escaped female Asian black bear and a male American black bear. In 1859, an American black bear and a Eurasian brown bear were bred together in the London Zoological Gardens, but the three cubs that were born died before they reached maturity. In The Variation of Animals and Plants under Domestication, Charles Darwin noted: In the nine-year Report it is stated that the bears had been seen in the zoological gardens to couple but to 1848 most had conceived. In the reports published since this date three species have produced young... An American black bear shot in autumn 1986 in Michigan was thought by some to be an American black bear/grizzly bear hybrid, due to its unusually large size and its proportionately larger braincase and skull. DNA testing was unable to determine whether it was a grizzly bear.
Listed alphabetically. American black bears occupied the majority of North America's forested regions. Today, they are limited to sparsely settled, forested areas. American black bears inhabit much of their original Canadian range, though they occur in the southern farmlands of Alberta and Manitoba; the total Canadian black bear population is between 396,000 and 476,000, based on surveys taken in the mid-1990s in seven Canadian provinces, though this estimate excludes American black bear populations in New Brunswick, the Northwest Territories, Nova Scotia and Saskatchewan. All provinces indicated stable populations of American black bears over the last decade; the current range of American black bears in the United States is constant throughout most of the northeast and within the Appalachian Mountains continuously from Maine to northern Georgia, the northern Midwest, the Rocky Mountain region, the West Coast and Alaska. However, it becomes fragmented or absent in other regions. Despite this, American black bears in those areas seem to have expanded their range during the last decade, such as with recent sightings in Ohio an
The Rocky Mountains known as the Rockies, are a major mountain range in western North America. The Rocky Mountains stretch more than 4,800 kilometers from the northernmost part of British Columbia, in western Canada, to New Mexico in the Southwestern United States. Located within the North American Cordillera, the Rockies are somewhat distinct from the Pacific Coast Ranges, Cascade Range, the Sierra Nevada, which all lie farther to the west; the Rocky Mountains formed 80 million to 55 million years ago during the Laramide orogeny, in which a number of plates began sliding underneath the North American plate. The angle of subduction was shallow, resulting in a broad belt of mountains running down western North America. Since further tectonic activity and erosion by glaciers have sculpted the Rockies into dramatic peaks and valleys. At the end of the last ice age, humans began inhabiting the mountain range. After Europeans, such as Sir Alexander Mackenzie, Americans, such as the Lewis and Clark expedition, began exploring the range and furs drove the initial economic exploitation of the mountains, although the range itself never experienced dense population.
Public parks and forest lands protect much of the mountain range, they are popular tourist destinations for hiking, mountaineering, hunting, mountain biking and snowboarding. The name of the mountains is a translation of an Amerindian name, related to Algonquian; the first mention of their present name by a European was in the journal of Jacques Legardeur de Saint-Pierre in 1752, where they were called "Montagnes de Roche". The Rocky Mountains are defined as stretching from the Liard River in British Columbia south to the Rio Grande in New Mexico; the Rockies vary in width from 110 to 480 kilometres. The Rocky Mountains are notable for containing the highest peaks in central North America; the range's highest peak is Mount Elbert located in Colorado at 4,401 metres above sea level. Mount Robson in British Columbia, at 3,954 metres, is the highest peak in the Canadian Rockies; the eastern edge of the Rockies rises above the Interior Plains of central North America, including the Sangre de Cristo Mountains of New Mexico and Colorado, the Front Range of Colorado, the Wind River Range and Big Horn Mountains of Wyoming, the Absaroka-Beartooth ranges and Rocky Mountain Front of Montana and the Clark Range of Alberta.
The western edge of the Rockies includes ranges such as the Wasatch near Salt Lake City and the Bitterroots along the Idaho-Montana border. The Great Basin and Columbia River Plateau separate these subranges from distinct ranges further to the west. In Canada, the western edge of the Rockies is formed by the huge Rocky Mountain Trench, which runs the length of British Columbia from its beginnings in the middle Flathead River valley in western Montana to the south bank of the Liard River. Geographers define three main groups of the Canadian Rockies: the Continental Ranges, Hart Ranges, Muskwa Ranges; the Rockies do not extend into central British Columbia. Other mountain ranges continue beyond the Liard River, including the Selwyn Mountains in Yukon, the Brooks Range in Alaska, but those are not part of the Rockies, though they are part of the American Cordillera; the Continental Divide of the Americas is located in the Rocky Mountains and designates the line at which waters flow either to the Atlantic or Pacific Oceans.
Triple Divide Peak in Glacier National Park is so named because water falling on the mountain reaches not only the Atlantic and Pacific but Hudson Bay as well. Farther north in Alberta, the Athabasca and other rivers feed the basin of the Mackenzie River, which has its outlet on the Beaufort Sea of the Arctic Ocean. Human population is not dense in the Rocky Mountains, with an average of four people per square kilometer and few cities with over 50,000 people. However, the human population grew in the Rocky Mountain states between 1950 and 1990; the forty-year statewide increases in population range from 35% in Montana to about 150% in Utah and Colorado. The populations of several mountain towns and communities have doubled in the last forty years. Jackson, increased 260%, from 1,244 to 4,472 residents, in forty years; the rocks in the Rocky Mountains were formed. The oldest rock is Precambrian metamorphic rock. There is Precambrian sedimentary argillite, dating back to 1.7 billion years ago. During the Paleozoic, western North America lay underneath a shallow sea, which deposited many kilometers of limestone and dolomite.
In the southern Rocky Mountains, near present-day Colorado, these ancestral rocks were disturbed by mountain building 300 Ma, during the Pennsylvanian. This mountain-building produced the Ancestral Rocky Mountains, they consisted of Precambrian metamorphic rock forced upward through layers of the limestone laid down in the shallow sea. The mountains eroded throughout the late Paleozoic and early Mesozoic, leaving extensive deposits of sedimentary rock. Terranes began colliding with the western edge of North America in the Mississippian, causing the Antler orogeny. For 270 million years, the focus of the effects of plate collisions were near the edge of the North American plate boundary, far to the west of the Rocky Mountain region, it was. The current Rocky Mountains arose in the Laramide orogeny from between 55 Ma. For the Canadi
Theodore Roosevelt Jr. was an American statesman, conservationist and writer who served as the 26th president of the United States from 1901 to 1909. He served as the 25th vice president of the United States from March to September 1901 and as the 33rd governor of New York from 1899 to 1900; as a leader of the Republican Party during this time, he became a driving force for the Progressive Era in the United States in the early 20th century. His face is depicted on Mount Rushmore, alongside those of George Washington, Thomas Jefferson, Abraham Lincoln. In polls of historians and political scientists, Roosevelt is ranked as one of the five best presidents. Roosevelt was born a sickly child with debilitating asthma, but he overcame his physical health problems by embracing a strenuous lifestyle, he integrated his exuberant personality, vast range of interests, world-famous achievements into a "cowboy" persona defined by robust masculinity. Home-schooled, he began a lifelong naturalist avocation before attending Harvard College.
His book, The Naval War of 1812, established his reputation as both a learned historian and as a popular writer. Upon entering politics, he became the leader of the reform faction of Republicans in New York's state legislature. Following the near-simultaneous deaths of his wife and mother, he escaped to a cattle ranch in the Dakotas. Roosevelt served as Assistant Secretary of the Navy under President William McKinley, but resigned from that post to lead the Rough Riders during the Spanish–American War. Returning a war hero, he was elected Governor of New York in 1898. After the death of Vice President Garret Hobart, the New York state party leadership convinced McKinley to accept Roosevelt as his running mate in the 1900 election. Roosevelt campaigned vigorously, the McKinley-Roosevelt ticket won a landslide victory based on a platform of peace and conservation. After taking office as Vice President in March 1901, he assumed the presidency at age 42 following McKinley's assassination that September, remains the youngest person to become President of the United States.
As a leader of the Progressive movement, he championed his "Square Deal" domestic policies, promising the average citizen fairness, breaking of trusts, regulation of railroads, pure food and drugs. Making conservation a top priority, he established many new national parks and monuments intended to preserve the nation's natural resources. In foreign policy, he focused on Central America, he expanded the Navy and sent the Great White Fleet on a world tour to project the United States' naval power around the globe. His successful efforts to broker the end of the Russo-Japanese War won him the 1906 Nobel Peace Prize, he avoided controversial money issues. Elected in 1904 to a full term, Roosevelt continued to promote progressive policies, many of which were passed in Congress. Roosevelt groomed his close friend, William Howard Taft, Taft won the 1908 presidential election to succeed him. Frustrated with Taft's conservatism, Roosevelt belatedly tried to win the 1912 Republican nomination, he failed, walked out and founded a third party, the Progressive, so-called "Bull Moose" Party, which called for wide-ranging progressive reforms.
He ran in the 1912 election and the split allowed the Democratic nominee Woodrow Wilson to win the election. Following his defeat, Roosevelt led a two-year expedition to the Amazon basin, where he nearly died of tropical disease. During World War I, he criticized President Wilson for keeping the country out of the war with Germany, his offer to lead volunteers to France was rejected. Though he had considered running for president again in 1920, Roosevelt's health continued to deteriorate, he died in 1919. Theodore Roosevelt Jr. was born on October 1858, at East 20th Street in New York City. He was the second of four children born to socialite Martha Stewart "Mittie" Bulloch and businessman and philanthropist Theodore Roosevelt Sr.. He had an older sister, Anna, a younger brother, a younger sister, Corinne. Elliott was the father of First Lady Anna Eleanor Roosevelt, the wife of Theodore's distant cousin, President Franklin Delano Roosevelt, his paternal grandfather was of Dutch descent. Theodore Sr. was the fifth son of businessman Cornelius Van Schaack "C.
V. S." Roosevelt and Margaret Barnhill. Theodore's fourth cousin, James Roosevelt I, a businessman, was the father of President Franklin Delano Roosevelt. Mittie was the younger daughter of Major James Stephens Bulloch and Martha P. "Patsy" Stewart. Through the Van Schaacks, Roosevelt was a descendant of the Schuyler family. Roosevelt's youth was shaped by his poor health and debilitating asthma, he experienced sudden nighttime asthma attacks that caused the experience of being smothered to death, which terrified both Theodore and his parents. Doctors had no cure, he was energetic and mischievously inquisitive. His lifelong interest in zoology began at age seven. Having learned the rudiments of taxidermy, he filled his makeshift museum with animals that he killed or caught. At age nine, he recorded his observation of insects in a paper entitled "The Natural History of Insects". Roosevelt'
Salamanders are a group of amphibians characterized by a lizard-like appearance, with slender bodies, blunt snouts, short limbs projecting at right angles to the body, the presence of a tail in both larvae and adults. All present-day salamander families are grouped together under the order Urodela. Salamander diversity is most abundant in the Northern Hemisphere and most species are found in the Holarctic ecozone, with some species present in the Neotropical zone. Salamanders have more than four toes on their front legs and five on their rear legs, but some species have fewer digits and others lack hind limbs, their permeable skin makes them reliant on habitats in or near water or other cool, damp places. Some salamander species are aquatic throughout their lives, some take to the water intermittently, others are terrestrial as adults, they are capable of regenerating lost limbs, as well as other damaged parts of their bodies. Researchers hope to reverse engineer the remarkable regenerative processes for potential human medical applications, such as brain and spinal cord injury treatment or preventing harmful scarring during heart surgery recovery.
Members of the family Salamandridae are known as newts and lack the costal grooves along the sides of their bodies typical of other groups. The skin of some species contains the powerful poison tetrodotoxin. Salamanders lay eggs in water and have aquatic larvae, but great variation occurs in their lifecycles; some species in harsh environments reproduce while still in the larval state. The skin lacks scales and is moist and smooth to the touch, except in newts of the Salamandridae, which may have velvety or warty skin, wet to the touch; the skin may be drab or brightly colored, exhibiting various patterns of stripes, spots, blotches, or dots. Male newts become colored during the breeding season. Cave species dwelling in darkness lack pigmentation and have a translucent pink or pearlescent appearance. Salamanders range in size from the minute salamanders, with a total length of 2.7 cm, including the tail, to the Chinese giant salamander which reaches 1.8 m and weighs up to 65 kg. Most, are between 10 and 20 cm in length.
An adult salamander resembles a small lizard, having a basal tetrapod body form with a cylindrical trunk, four limbs, a long tail. Except in the family Salamandridae, the head and tail have a number of vertical depressions in the surface which run from the mid-dorsal region to the ventral area and are known as costal grooves, their function seems to be to help keep the skin moist by channeling water over the surface of the body. Some aquatic species, such as sirens and amphiumas, have reduced or absent hind limbs, giving them an eel-like appearance, but in most species, the front and rear limbs are about the same length and project sidewards raising the trunk off the ground; the feet are broad with short digits four on the front feet and five on the rear. Salamanders do not have claws, the shape of the foot varies according to the animal's habitat. Climbing species have elongated, square-tipped toes, while rock-dwellers have larger feet with short, blunt toes; the tree-climbing salamander has plate-like webbed feet which adhere to smooth surfaces by suction, while the rock-climbing Hydromantes species from California have feet with fleshy webs and short digits and use their tails as an extra limb.
When ascending, the tail props up the rear of the body, while one hind foot moves forward and swings to the other side to provide support as the other hind foot advances. In larvae and aquatic salamanders, the tail is laterally flattened, has dorsal and ventral fins, undulates from side to side to propel the animal through the water. In the families Ambystomatidae and Salamandridae, the male's tail, larger than that of the female, is used during the amplexus embrace to propel the mating couple to a secluded location. In terrestrial species, the tail moves to counterbalance the animal as it runs, while in the arboreal salamander and other tree-climbing species, it is prehensile; the tail is used by certain plethodontid salamanders that can jump, to help launch themselves into the air. The tail is used as a storage organ for proteins and lipids, it functions as a defense against predation, when it may be lashed at the attacker or autotomised when grabbed. Unlike frogs, an adult salamander is able to regenerate its tail when these are lost.
The skin of salamanders, in common with other amphibians, is thin, permeable to water, serves as a respiratory membrane, is well-supplied with glands. It has cornified outer layers, renewed periodically through a skin shedding process controlled by hormones from the pituitary and thyroid glands. During moulting, the skin breaks around the mouth, the animal moves forwards through the gap to shed the skin; when the front limbs have been worked clear, a series of body ripples pushes the skin towards the rear. The hind limbs are extracted and push the skin farther back, before it is freed by friction as the salamander moves forward with the tail pressed against the ground; the animal then eats the resulting sloughed skin. Glands in the skin discharge mucus which keeps the skin moist, an important factor in skin respiration and thermoregulation; the sticky layer helps protect against bacterial infections and molds, reduces friction when swimming, makes the animal slippery and more difficult for predators to catch.
Granular glands scattered on the upper surface the head and tail, produce repel