Tuesday, 12 January 2010
(Scott Camazine web.mac.com/camazine)
Salamander is a common name of approximately 500 species of amphibians. They are typically characterized by 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. Some salamander species are fully aquatic throughout life, some take to the water intermittently, and some are entirely terrestrial as adults. Uniquely among vertebrates, they are capable of regenerating lost limbs, as well as other body parts.
The life history of salamanders is similar to that of other amphibians such as frogs and toads. Most species fertilise the eggs internally, with the male depositing a sac of sperm in the female's cloaca. The most primitive salamanders, grouped together as the Cryptobranchoidea, 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) exhibit no larval stage at all, with the young hatching as miniature versions of the adult.
Neoteny 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 terrestrially.
Mythology and popular culture
Main articles: Salamander (legendary creature) and Salamander (legendary creature) in 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 Talmud as well as in the writings of Aristotle, Pliny, Conrad Lycosthenes, Benvenuto Cellini, Ray Bradbury, David Weber, Paracelsus and Leonardo da Vinci.(http://en.wikipedia.org/wiki/Salamander)
1)"Phylogenetic relationships of the salamander families: an analysis of the congruence among morphological and molecular characters". Herpetological Monographs 7 (7): 77–93. 1993. c1993.
2)Lanza, B., Vanni, S., & Nistri, A. (1998). Cogger, H.G. & Zweifel, R.G.. ed. Encyclopedia of Reptiles and Amphibians. San Diego: Academic Press. pp. 60–68.
9)Ashcroft, Frances (2002). Life at the Extremes: The Science of Survival. Berkeley, CA: University of California Press. p. 112.
Posted by Merve at 17:23