Salamander
Overview
Salamander is a common name of approximately 500 species of amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

s. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant species are grouped together as the Urodela. Most salamanders have four toes on their front legs and five on their rear legs.
Encyclopedia
Salamander is a common name of approximately 500 species of amphibian
Amphibian
Amphibians , are a class of vertebrate animals including animals such as toads, frogs, caecilians, and salamanders. They are characterized as non-amniote ectothermic tetrapods...

s. They are typically characterized by a superficially lizard-like appearance, with their slender bodies, short noses, and long tails. All known fossils and extinct species fall under the order Caudata, while sometimes the extant species are grouped together as the Urodela. Most salamanders have four toes on their front legs and five on their rear legs. Their moist skin usually makes them reliant on habitats in or near water, or under some protection (e.g., moist ground), often in a wetland
Wetland
A wetland is an area of land whose soil is saturated with water either permanently or seasonally. Wetlands are categorised by their characteristic vegetation, which is adapted to these unique soil conditions....

. Some salamander species are fully aquatic throughout life, some take to the water intermittently, and some are entirely terrestrial as adults. Unique among vertebrate
Vertebrate
Vertebrates are animals that are members of the subphylum Vertebrata . Vertebrates are the largest group of chordates, with currently about 58,000 species described. Vertebrates include the jawless fishes, bony fishes, sharks and rays, amphibians, reptiles, mammals, and birds...

s, they are capable of regenerating
Regeneration (biology)
In biology, regeneration is the process of renewal, restoration, and growth that makes genomes, cells, organs, organisms, and ecosystems resilient to natural fluctuations or events that cause disturbance or damage. Every species is capable of regeneration, from bacteria to humans. At its most...

 lost limbs, as well as other body parts.

Physical characteristics

Mature salamanders generally have an ancestral tetrapod
Tetrapod
Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...

 body form with a cylindrical trunk, four limbs and a long tail. Some species such as sirens and amphiumas have reduced or absent hindlimbs, giving them a more eel
Eel
Eels are an order of fish, which consists of four suborders, 20 families, 111 genera and approximately 800 species. Most eels are predators...

-like appearance. Most species have four clawless toes on the forelimbs and five on the hind limbs. 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 that is dry to the touch. The skin may be drab or brightly colored, exhibiting various patterns of stripes, bars, spots, blotches or dots. Male newts become dramatically 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
Thorius
Thorius also known as Minute Salamanders is a genus of salamanders in the Plethodontidae family distributed from Western and Southern North America south to Brazil. The members of this genus are characterized by a small body - some species are less than 2 cm in length.-Species:This genus is...

, with a total length of 2.7 centimetres (1.1 in), including the tail, to the Chinese giant salamander
Chinese giant salamander
The Chinese giant salamander is the largest salamander in the world, reaching a length of 180 cm , although it rarely – if ever – reaches that size today...

 which reaches 1.8 metres (5.9 ft) and weighs up to 65 kg (143.3 lb). Most, however, are between 10 centimetres (3.9 in) and 20 centimetres (7.9 in) in length.

Physiology

Respiration
Respiration (physiology)
'In physiology, respiration is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction...

 differs among the different species of salamanders. Species that lack lungs respire through gills. In most cases, these are external gills, visible as tufts on either side of the head, although the amphiuma
Amphiuma
Amphiuma is a genus of aquatic salamanders, the only extant genus within the family Amphiumidae . They are also known to fishermen as "conger eels" or "congo snakes", which are zoologically incorrect designations...

s have internal gills and gill slits. Some salamanders that are terrestrial have lungs that are used in respiration, although these are simple and sac-like, unlike the more complex organs found in mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...

s. Many species, such as the olm
Olm
The olm, or proteus , is a blind amphibian endemic to the subterranean waters of caves of the Dinaric karst of southern Europe. It lives in the waters that flow underground through this extensive limestone region including waters of the Soča river basin near Trieste in Italy, through to southern...

, have both lungs and gills as adults.

Some terrestrial species lack both lungs and gills and perform gas exchange through their skin, a process known as valerian respiration in which the capillary beds are spread throughout the epidermis, and inside the mouth. Even some species with lungs can respire through the skin in this manner.

The skin of salamanders secretes mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

, which helps keep the animal moist when on dry land, and maintains their salt balance while in water, as well as providing a lubricant during swimming. Salamanders also secrete poison from glands in their skin, and some additionally have skin glands for secreting courtship pheromone
Pheromone
A pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...

s. Salamanders regularly shed the outer layer of their skin (the epidermis) as they grow, and then eat the resulting slough.

Feeding

Terrestrial salamanders catch their prey by rapidly extending a sticky tongue which adheres to the prey, allowing it to be pulled into the mouth. In combination with tongue movements, salamanders may lunge forward and grasp prey with their jaws, securing them with small teeth on the margins of their jaws.

In the lungless salamander
Lungless salamander
The 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...

s, muscles surrounding the hyoid bone
Hyoid bone
The hyoid bone is a horseshoe-shaped bone situated in the anterior midline of the neck between the chin and the thyroid cartilage. At rest, it lies at the level of the base of the mandible in the front and the third cervical vertebra behind.Unlike other bones, the hyoid is only distantly...

 contract to create pressure and actually "shoot" the hyoid bone out of the mouth along with the tongue. The tip of the tongue is composed of a mucus
Mucus
In vertebrates, mucus is a slippery secretion produced by, and covering, mucous membranes. Mucous fluid is typically produced from mucous cells found in mucous glands. Mucous cells secrete products that are rich in glycoproteins and water. Mucous fluid may also originate from mixed glands, which...

 which creates a sticky end to which the prey is captured. Muscles in the pelvic region are used in order to reel the tongue and the hyoid back to its original position.

Many of the highly aquatic species, however, have no muscles in the tongue, and do not use it for capturing prey, while most other species have a mobile tongue, but without the adaptations to the hyoid bone. Most species of salamander have small teeth in both the upper and lower jaws. Unlike frog
Frog
Frogs are amphibians in the order Anura , formerly referred to as Salientia . Most frogs are characterized by a short body, webbed digits , protruding eyes and the absence of a tail...

s, even the larvae of salamanders possess these teeth.

To find their prey, salamanders use trichromatic color vision
Color vision
Color vision is the capacity of an organism or machine to distinguish objects based on the wavelengths of the light they reflect, emit, or transmit...

 in the ultraviolet
Ultraviolet
Ultraviolet light is electromagnetic radiation with a wavelength shorter than that of visible light, but longer than X-rays, in the range 10 nm to 400 nm, and energies from 3 eV to 124 eV...

 range based on two photoreceptor types maximally sensitive around 450 nm, 500 nm and 570 nm. Permanently subterranean salamanders have reduced eyes, which may even be covered by a layer of skin. The larvae, and the adults of some highly aquatic species, also have a lateral line
Lateral line
The lateral line is a sense organ in aquatic organisms , used to detect movement and vibration in the surrounding water. Lateral lines are usually visible as faint lines running lengthwise down each side, from the vicinity of the gill covers to the base of the tail...

 organ, similar to that of fish, which can detect changes in water pressure. Salamanders have no external ear
Ear
The ear is the organ that detects sound. It not only receives sound, but also aids in balance and body position. The ear is part of the auditory system....

, and only a vestigial middle ear.

Defense

Some salamander species use tail autotomy
Autotomy
Autotomy or self amputation is the act whereby an animal severs one or more of its own appendages, usually as a self-defense mechanism designed to elude a predator's grasp...

 to escape predators. The tail will drop off and wriggle around for a little while, and the salamanders will either run away or stay still enough to not be noticed while the predator is distracted. Salamanders routinely regenerate complex tissues. Within only a few weeks of losing a piece of limb, a salamander perfectly reforms the missing structure. They can also produce a white milky substance that is poisonous.

Distribution

Salamanders split off from the other amphibians during the Mid to Late Permian, and initially were similar to modern members of the Cryptobranchoidea
Cryptobranchoidea
Cryptobranchoidea is a suborder of salamanders found in the eastern United States, China, and Japan. They are known as primitive salamanders, in contrast to Salamandroidea, or advanced salamander....

. Their resemblance to lizard
Lizard
Lizards are a widespread group of squamate reptiles, with nearly 3800 species, ranging across all continents except Antarctica as well as most oceanic island chains...

s is the result of symplesiomorphy
Symplesiomorphy
In cladistics, a symplesiomorphy or symplesiomorphic character is a trait which is shared between two or more taxa, but which is also shared with other taxa which have an earlier last common ancestor with the taxa under consideration...

, their common retention of the primitive tetrapod
Tetrapod
Tetrapods are vertebrate animals having four limbs. Amphibians, reptiles, birds and mammals are all tetrapods; even snakes and other limbless reptiles and amphibians are tetrapods by descent. The earliest tetrapods evolved from the lobe-finned fishes in the Devonian...

 body plan, and they are no more closely related to lizards than they are to mammals – or to birds for that matter. Their nearest relatives are the frogs and toads, within Batrachia.

Caudates are found on all continents except for Australia, Antarctica, and most of Africa. One-third of the known salamander species are found in North America. The highest concentration of these is found in the Appalachian Mountains
Appalachian Mountains
The Appalachian Mountains #Whether the stressed vowel is or ,#Whether the "ch" is pronounced as a fricative or an affricate , and#Whether the final vowel is the monophthong or the diphthong .), often called the Appalachians, are a system of mountains in eastern North America. The Appalachians...

 region. Species of salamander are numerous and found in most moist or arid habitats in the northern hemisphere. They usually live in or near brooks, creeks, ponds, and other moist locations.

Development

The life history of salamanders is similar to that of other amphibians such as frogs and toad
Toad
A toad is any of a number of species of amphibians in the order Anura characterized by dry, leathery skin , short legs, and snoat-like parotoid glands...

s. Most species fertilize the eggs internally, with the male depositing a sac of sperm in the female's cloaca
Cloaca
In zoological anatomy, a cloaca is the posterior opening that serves as the only such opening for the intestinal, reproductive, and urinary tracts of certain animal species...

. The most primitive salamanders – those grouped together as the Cryptobranchoidea
Cryptobranchoidea
Cryptobranchoidea is a suborder of salamanders found in the eastern United States, China, and Japan. They are known as primitive salamanders, in contrast to Salamandroidea, or advanced salamander....

 – instead exhibit external fertilisation. The eggs are laid in a moist environment, often a pond, but sometimes moist soil, or inside bromeliads. Some species are ovoviviparous, with the female retaining the eggs inside her body until they hatch.

A larval stage follows in which the organism is fully aquatic or land dwelling, and possesses gills. Depending on species, the larval stage may or may not possess legs. The larval stage may last anything from days to years, depending on the species. Some species (such as Dunn's Salamander
Dunn's Salamander
The Dunn's Salamander is a species of salamander in the Plethodontidae family.It is endemic to the United States....

) exhibit no larval stage at all, with the young hatching as miniature versions of the adult.

Neoteny
Neoteny
Neoteny , also called juvenilization , is one of the two ways by which paedomorphism can arise. Paedomorphism is the retention by adults of traits previously seen only in juveniles, and is a subject studied in the field of developmental biology. In neoteny, the physiological development of an...

 has been observed in all salamander families, in which an individual may retain gills into sexual maturity. This may be universally possible in all salamander species. More commonly, however, metamorphosis continues with the loss of gills, the growth (or increase in size) of legs, and the capability of the animal to function

Declining populations

A general decline in living amphibian species, caused by the fungal disease chytridiomycosis
Chytridiomycosis
Chytridiomycosis is an infectious disease of amphibians, caused by the chytrid Batrachochytrium dendrobatidis, a non-hyphal zoosporic fungus. Chytridiomycosis has been linked to dramatic population declines or even extinctions of amphibian species in western North America, Central America, South...

, has had a significant effect on the salamander as well. While researchers have not yet found a direct link between the fungus and the population decline, they do believe it has played a role. Researchers also cite deforestation
Deforestation
Deforestation is the removal of a forest or stand of trees where the land is thereafter converted to a nonforest use. Examples of deforestation include conversion of forestland to farms, ranches, or urban use....

 and climate change as possible contributing factors. This is based on surveys conducted in Guatemala during the 1970s as well as recently. Especially affected were Pseudoeurycea brunnata
Pseudoeurycea brunnata
Pseudoeurycea brunnata is a species of salamander in the Plethodontidae family.It is found in Guatemala and Mexico.Its natural habitat is subtropical or tropical moist montanes.It is threatened by habitat loss.-Source:...

 and Pseudoeurycea goebeli
Pseudoeurycea goebeli
Pseudoeurycea goebeli is a species of salamander in the Plethodontidae family.It is found in Guatemala and Mexico.Its natural habitat is subtropical or tropical moist montanes.It is threatened by habitat loss.-Source:...

, both of which were abundant during the 1970s.

Taxonomy

There are ten families belonging to the order Caudata, divided into three suborders. The clade Neocaudata is often used to separate Cryptobranchoidea and Salamandroidea from the Sirenoidea.
Cryptobranchoidea
Cryptobranchoidea
Cryptobranchoidea is a suborder of salamanders found in the eastern United States, China, and Japan. They are known as primitive salamanders, in contrast to Salamandroidea, or advanced salamander....

 (Giant salamanders)
FamilyCommon NamesExample Species
Example Photo
Cryptobranchidae Giant salamanders Hellbender
Hellbender
The hellbender , also known as the hellbender salamander, is a species of giant salamander that is endemic to eastern North America...

 (Cryptobranchus alleganiensis)
Hynobiidae Asiatic salamanders Hida Salamander
Hida Salamander
The Hida Salamander is a species of salamander in the Hynobiidae family.It is endemic to Japan.Its natural habitats are temperate forests and rivers.-References:* Kaneko, Y. & Matsui, M. 2004....

 (Hynobius kimurae)
Salamandroidea
Salamandroidea
Salamandroidea is a suborder of salamanders, referred to as advanced salamanders. The members of the suborder are found worldwide except for Antarctica, Southern Sahara, and Oceania. They differ from suborder Cryptobranchoidea as their angular and prearticular bones in their lower jaw are fused and...

 (Advanced salamanders)
Ambystomatidae Mole salamanders Marbled Salamander
Marbled Salamander
The Marbled Salamander is a species of mole salamander found in the eastern United States.- Description :The Marbled Salamander is a stocky, boldly banded salamander. The bands of females tend to be gray, while those of males are more white. Adults can grow to about 11 cm, , a bit small compared...

 (Ambystoma opacum)
Amphiumidae Amphiumas or Congo eels Two-toed Amphiuma
Two-toed Amphiuma
The two-toed amphiuma is a snake-like salamander found chiefly in the southeastern United States. It is commonly, but incorrectly, called "congo snake", "conger eel" or the "blind eel". It has a thick body about long, four vestigial legs that end in two or three toes which are virtually useless,...

 (Amphiuma means)
Dicamptodontidae Pacific giant salamanders Pacific Giant Salamander
Pacific giant salamander
Pacific giant salamanders are a family of large salamanders.The family includes only a single genus, Dicamptodon. The genus was formerly thought to contain two species, Cope's Giant Salamander on the Olympic Peninsula, Washington, and the Pacific giant salamander Pacific giant salamanders...

 (Dicamptodon tenebrosus)
Plethodontidae
Lungless salamander
The 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...

Lungless salamanders Red Back Salamander
Red Back Salamander
The red back salamander is a small, hardy woodland salamander. It inhabits wooded slopes in Eastern North America; west to Missouri; south to North Carolina; and north from southern Quebec and the Maritime Provinces in Canada to Minnesota...

 (Plethodon cinereus)
Proteidae Mudpuppies and olms Olm
Olm
The olm, or proteus , is a blind amphibian endemic to the subterranean waters of caves of the Dinaric karst of southern Europe. It lives in the waters that flow underground through this extensive limestone region including waters of the Soča river basin near Trieste in Italy, through to southern...

 (Proteus anguinus)
Rhyacotritonidae Torrent salamanders Southern Torrent Salamander
Southern Torrent Salamander
The Southern Torrent Salamander is a member of the Rhyacotriton family of salamanders. R. variegatus has the common name Southern Torrent Salamander for it is the species of Torrent Salamander found the furthest south in the region. It is a small salamander endemic to the Pacific Northwest from...

 (Rhyacotriton variegatus)
Salamandridae
Salamandridae
Salamandridae is a family of salamanders consisting of true salamanders and newts. Currently, 74 species have been identified in the northern hemisphere - Europe, Asia, the northern tip of Africa and North America...

Newts and true salamanders Alpine Newt
Alpine Newt
The Alpine Newt is a newt of the Salamander order Caudata in the class of Amphibians.-Description:...

 (Triturus alpestris)
Sirenoidea (Sirens)
Sirenidae Sirens Greater Siren
Greater Siren
The greater siren is an eel-like amphibian. The largest of the Sirens, they can grow from to in length. They range in color from black to brown, and have a lighter gray or yellow underbelly....

 (Siren lacertina)

Mythology and popular culture

Numerous legends have developed around the salamander over the centuries, many related to fire. This connection likely originates from the tendency of many salamanders to dwell inside rotting logs. When placed into a fire, the salamander would attempt to escape from the log, lending to the belief that salamanders were created from flames — a belief that gave the creature its name.

Associations of the salamander with fire appear in the writings of Aristotle
Aristotle
Aristotle was a Greek philosopher and polymath, a student of Plato and teacher of Alexander the Great. His writings cover many subjects, including physics, metaphysics, poetry, theater, music, logic, rhetoric, linguistics, politics, government, ethics, biology, and zoology...

, Pliny
Pliny the Elder
Gaius Plinius Secundus , better known as Pliny the Elder, was a Roman author, naturalist, and natural philosopher, as well as naval and army commander of the early Roman Empire, and personal friend of the emperor Vespasian...

, the Talmud
Talmud
The Talmud is a central text of mainstream Judaism. It takes the form of a record of rabbinic discussions pertaining to Jewish law, ethics, philosophy, customs and history....

, Conrad Lycosthenes
Conrad Lycosthenes
Conrad Lycosthenes was an Alsatian humanist and encyclopedist.-Life:He was born in Rouffach in Alsace on August 8, 1518, the son of Theobald Wolffhart and Elizabeth Kürsner, sister of the Protestant theologian Conrad Pellicanus...

, Benvenuto Cellini
Benvenuto Cellini
Benvenuto Cellini was an Italian goldsmith, sculptor, painter, soldier and musician, who also wrote a famous autobiography. He was one of the most important artists of Mannerism.-Youth:...

, Ray Bradbury
Ray Bradbury
Ray Douglas Bradbury is an American fantasy, horror, science fiction, and mystery writer. Best known for his dystopian novel Fahrenheit 451 and for the science fiction stories gathered together as The Martian Chronicles and The Illustrated Man , Bradbury is one of the most celebrated among 20th...

, David Weber
David Weber
David Mark Weber is an American science fiction and fantasy author. He was born in Cleveland, Ohio. Weber and his wife Sharon live in Greenville, South Carolina with their three children and "a passel of dogs"....

, Paracelsus
Paracelsus
Paracelsus was a German-Swiss Renaissance physician, botanist, alchemist, astrologer, and general occultist....

 and Leonardo da Vinci
Leonardo da Vinci
Leonardo di ser Piero da Vinci was an Italian Renaissance polymath: painter, sculptor, architect, musician, scientist, mathematician, engineer, inventor, anatomist, geologist, cartographer, botanist and writer whose genius, perhaps more than that of any other figure, epitomized the Renaissance...

.

Implications of limb regeneration as applied to humans

Salamanders' limb regeneration has been the focus of significant interest among scientists. A theory persists in the scientific community that such regeneration could be artificially recreated in humans using stem cell
Stem cell
This article is about the cell type. For the medical therapy, see Stem Cell TreatmentsStem cells are biological cells found in all multicellular organisms, that can divide and differentiate into diverse specialized cell types and can self-renew to produce more stem cells...

s. Axolotl
Axolotl
The axolotl , Ambystoma mexicanum, is a neotenic salamander, closely related to the Tiger Salamander. Larvae of this species fail to undergo metamorphosis, so the adults remain aquatic and gilled. It is also called ajolote...

s have been highlighted for research.

External links

  • Tree of Life: Caudata
  • Salamanders.nl - The Official Dutch Newt & Salamander Society Site
  • Caudata Culture
  • Salamandridae
  • Urodela Info Center at Google Groups
    Google Groups
    Google Groups is a service from Google Inc. that supports discussion groups, including many Usenet newsgroups, based on common interests. The service was started in 1995 as Deja News, and was transitioned to Google Groups after a February 2001 buyout....

  • Critter Crossings: Salamander Tunnels at Department of Transportation
    Department of Transportation
    The Department of Transportation is the most common name for a government agency in North America devoted to transportation. The largest is the United States Department of Transportation, which oversees interstate travel. All U.S. states, Canadian provinces, and many local agencies also have...


Regional lists


Media

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
x
OK