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Newts
Smooth newt (Lissotriton vulgaris)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Lissamphibia
Order: Caudata
Family: Salamandridae
Subfamily: Pleurodelinae

A newt is an amphibian of the Salamandridae family, although not all aquatic salamanders are considered newts. Newts are classified in the subfamily Pleurodelinae of the family Salamandridae, and are found in North America, Europe and Asia. Newts metamorphose through three distinct developmental life stages: aquatic larva, terrestrial juvenile (called an eft[1]), and adult. Adult newts have lizard-like bodies and may be either fully aquatic, living permanently in the water, or semi-aquatic, living terrestrially but returning to the water each year to breed.

Contents

Etymology

The etymology for this term has gone through a complex twist of old Middle English variations. The oldest form of the name is eft, which is still used for newly metamorphosed specimens, but according to the Oxford English Dictionary it changed for unknown reasons first to euft and then to ewt. For some time it remained as an ewt, but the "n" from the indefinite article an shifted to form a newt. The sexually mature stage was also called an ewte, with similar etymology roots linking an ewte, newt, "euft", and eft: "small lizard-like animal," [3].

Characteristics

A red-spotted newt (eft stage) showing bright aposematic colouration to warn predators of its highly toxic skin.

Like all members of the order Caudata, newts are characterised by a lizard-like body with four equal sized limbs and a distinct tail. Aquatic larvae have true teeth on both upper and lower jaws and external gills.[2] They have the ability to regenerate limbs, eyes, spinal cords, hearts, intestines, and upper and lower jaws. The cells at the site of the injury have the ability to de-differentiate, reproduce rapidly, and differentiate again to create a new limb or organ. One theory is that the de-differentiated cells are related to tumour cells since chemicals which produce tumours in other animals will produce additional limbs in newts.[3]

Development

An alpine newt larva (Mesotriton alpestris) showing external gills.

The main breeding season for newts is between the months of February and June. After courtship rituals of varying complexity, which take place in ponds or slow moving streams, the male newt transfers a spermatophore which is taken up by the female. Fertilised eggs are laid singly and are usually attached to aquatic plants. This distinguishes them from the free-floating eggs of frogs or toads, that are laid in clumps or in strings. Plant leaves are usually folded over and adhered to the eggs to protect them. The tadpoles, which resemble fish fry but are distinguished by their feathery external gills, hatch out in about three weeks. After hatching they eat algae, small invertebrates or other tadpoles.

During the next few months the tadpoles undergo metamorphosis, during which they develop legs, and the gills change into air-breathing lungs.[4] Some species, such as the North American newts, also become more brightly coloured during this phase. Once fully metamorphosised they leave the water and live a terrestrial life, when they are known as "efts".[5] Only when the eft reaches adulthood will the North American species return to live in water, rarely venturing back onto the land. Conversely, most European species live their adult lives on land and only visit water to breed.[6]

Toxicity

Many newts produce toxins in their skin secretions as a defense mechanism against predators. Taricha newts of western North America are particularly toxic; the Rough-skinned newt (Taricha granulosa) of the Pacific Northwest produces more than enough tetrodotoxin to kill an adult human. A 29-year-old man in Coos Bay, Oregon, who had been drinking heavily, swallowed a rough-skin newt Taricha granulosa for a dare. He died later that day despite hospital treatment.[7]

Most newts can be safely handled, provided that the toxins they produce are not ingested or allowed to come in contact with mucous membranes or breaks in the skin.[7] After handling, proper hand-washing techniques should be followed due to the risk from the toxins they produce and bacteria they carry, such as salmonella. [8][9]. It is, however, illegal to handle or disturb Great Crested Newts in the UK without a licence.[10]

Systematics

About two thirds of all species of the family Salamandridae are commonly called "newts", compromising the following genera:

The term "newt" has traditionally been seen as an exclusively functional term for salamanders living in water, and not a systematic unit. The relationship between the genera has been uncertain, though there has been suggested that they constitute a natural systematic unit. Newer molecular analysis tend to support they actually do form a systematic unit.[11][12][13] Newts only appear in one subfamily of salamanders, the Pleurodelinae (of the family Salamandridae).[14] However, some of the genera sometimes listed as Pleurodelinae are not newts (Salamandrina and Euproctus). Whether these are basal to the subfamily (and thus the sister group of the newt group) or derived, making the newts an evolutionary grade (an "incomplete" systematic unit, where not all branches of the family tree belong to the group) is currently not known.[15][16]

Distribution

The three common European genera are the crested newts (Triturus spp.), the smooth and palmate newts (Lissotriton spp.) and the banded Newts (Ommatotriton spp.). Other species present in Europe are the Iberian ribbed newt (Plurodeles waltl), which is the largest of the European newts,[17] the pyrenean brook newt (Calotriton sp.); the European brook newt (Euproctus sp.) and the Alpine newt (Mesotriton alpestris).[12][18]

In North America, there are the Eastern newts (Notophthalmus spp.), of which the red-spotted newt (Notophthalmus viridescens) is the most abundant species, but it is limited to the area east of the Rocky Mountains. The three species of coastal or Western newts are the red-bellied newt, the California newt, and the rough-skinned newt, all of which belong to the genus Taricha, which is confined to the area west of the Rockies.[citation needed]

In Southeast Asia and Japan, species commonly encountered in the pet trade include the fire belly newts (Cynops spp.), the paddletail newts (Pachytriton spp.), the crocodile newts (Tylototriton spp.), and the warty newts (Paramesotriton spp.). In the Middle East there are the spotted newts (Neurergus spp.).[19]

Conservation status

Newt populations have fallen across the world, due to pollution or destruction of their breeding sites and terrestrial habitats, and countries such as the USA and the UK have taken steps to halt their decline.[20][21] In the UK they are protected under the Wildlife and Countryside Act 1981 and the Habitat Regulations Act 1994. It is illegal to catch, possess or handle Great Crested Newts without a licence and it is also illegal to cause them harm or death, or to disturb their habitat in any way. The IUCN Red List categorises the species as ‘lower risk’ [10][22] Although the other UK species, the smooth newt and palmate newt are not listed, the sale of either species is prohibited under the Wildlife and Countryside Act, 1981.[23]

In Europe, nine newts are listed as "strictly protected fauna species" under appendix II of the Convention on the Conservation of European Wildlife and Natural Habitats:[24]

The remaining European species are listed as "protected fauna species" under appendix III. [25]

Cultural references

References

  1. ^ Brockes, J. & A. Kumar. 2005. Newts. Current Biology. 15(2):R4244)
  2. ^ Heying, H. 2003. "Caudata" (On-line), Animal Diversity Web. [1] Accessed 2007-12-05
  3. ^ www.bioscience.utah.edu; Odelberg, S. Accessed 2007-01-24
  4. ^ www.scienceclarified.com Accessed 2007-12-01
  5. ^ http://lnr.cambridge.gov.uk/news/article.asp?ItemID=285 Accessed 2008-03-06
  6. ^ bbc.co.uk Factfile 478 Accessed 2007-11-30
  7. ^ a b c d see caudata.org Accessed 2007-11-28
  8. ^ Salmonellosis - Reptiles and Amphibians Accessed 2007-11-28
  9. ^ CDC MMWR: Reptile-Associated Salmonellosis: Selected States, 1998-2002Accessed 2007-11-28
  10. ^ a b bbc.co.uk Factfile 479 Accessed 2007-11-28
  11. ^ Titus, T. A. & A. Larson (1995):. A molecular phylogenetic perspective on the evolutionary radiation of the salamander family Salamandridae. Systematic Biology 44, pp 125-151.
  12. ^ a b Steinfartz, S., S. Vicario, J. W. Arntzen, & A. Caccone (2006): A Bayesian approach on molecules and behavior: reconsidering phylogenetic and evolutionary patterns of the Salamandridae with emphasis on Triturus newts. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
  13. ^ Weisrock, D. W., Papenfuss, T. J., Macey, J. R., Litvinchuk, S. N., Polymeni, R., Ugurtas, I. H., Zhao, E., Jowkar, H., & A. Larson (2006): A molecular assessment of phylogenetic relationships and lineage accumulation rates within the family Salamandridae (Amphibia, Caudata). Molecular Phylogenetics and Evolutio 41, pp 368-383.
  14. ^ Larson, A, Wake, D., & Devitt, T. (2007): Salamandridae, Newts and "True Salamanders". Tree of Life on-line project [2]
  15. ^ Montori, A. and P. Herrero (2004): Caudata. In Amphibia, Lissamphibia. García-París, M., Montori, A., and P. Herrero. Fauna Ibérica, vol. 24. Ramos M. A. et al. (eds.). Museo Nacional de Ciencias Naturales. CSIC. Madrid: pp 43-275
  16. ^ Weisrock, D. W., Papenfuss, T. J., Macey, J. R., Litvinchuk, S. N., Polymeni, R., Ugurtas, I. H., Zhao, E., Jowkar, H., & A. Larson (2006): A molecular assessment of phylogenetic relationships and lineage accumulation rates within the family Salamandridae (Amphibia, Caudata). Molecular Phylogenetics and Evolutio 41, pp 368-383.
  17. ^ www.calcadamemy.org; California Academy of Sciences Accessed 2007-12-05
  18. ^ Carranza, S. & Amat, F. (2005) Taxonomy, biogeography and evolution of Euproctus (Amphibia: Salamandridae), with the resurrection of the genus Calotriton and the description of a new endemic species from the Iberian Peninsula Zoological Journal of the Linnean Society 145 (4), 555–582.
  19. ^ livingunderworld.org; Amphibian Order:caudata ; Accessed 2007-02-05
  20. ^ USGS Amphibian Research Monitoring Initiative (Pacific Northwest Region) Accessed 2007-11-30
  21. ^ UK Biodiversity Action Plan Accessed 2007-11-30
  22. ^ bbc.co.uk Factfile 478 Accessed 2007-11-28
  23. ^ arkive.org Accessed 2007-11-30
  24. ^ Annexe II: Stricly protected fauna species Retrieved on 15 September 2008
  25. ^ Annexe III: Protected fauna species Retrieved on 15 September 2008
  26. ^ See "newt" "Armorial Gold's Heraldry Dictionary". Armorial Gold Heraldry Services. http://www.heraldryclipart.com/dn.html. Retrieved 18 November 2008. 
  27. ^ Macbeth: Full-text online, in Act IV Scene I

External links


1911 encyclopedia

Up to date as of January 14, 2010

From LoveToKnow 1911

NEWT (a corrupted form from "an evet" or "an effet," a term of Anglo-Saxon origin, still used in many parts of England),. the name usually applied to the aquatic members of the family Salamandridae which constitute the genus Molge, formerly known as Triton. But the name Triton, applied to these Batrachians by N. Laurenti (1768), has already been used by Linnaeus (Systema Naturae) for parts of the barnacle (Lepas anatifera). B. Merem (1820) proposed to substitute for it the name Molge, said to be derived from the Gr. MOXyns or MOXyos, "slow," in allusion to the movements of these animals on land. The similar name Molch designates these Batrachians in German.

The newts are very closely related to the true Salamanders, Salamandra, from which they differ principally in the shape of the tail, which is compressed, in relation to their aquatic habits during a considerable part of the active period. Their aquatic progression is effected principally by means of the tail, and during the act of swimming the legs are turned backwards and folded against the body and tail, so as to admit of the smallest possible degree of resistance.

A very marked sexual dimorphism prevails in most species of this genus, the males being more brilliantly coloured than the females and provided with a dorsal crest which attains its greatest development during the breeding season; lasting through the spring and the early summer. Later in the season the males more or less completely lose their crests and other nuptial ornaments, and the two sexes are more alike; they then retire on land, concealing themselves under stones, logs of wood, or in holes in damp earth, but leaving their retreat at night or in wet weather to search for earth-worms and slugs which constitute their principal food. In the water they are very destructive of tadpoles, insect larvae and crustaceans.

A remarkable feature of the newts, which they share with the other tailed Batrachians and the larvae of the frogs and toads, is the great facility with which they regenerate lost parts, such as the tail, limbs, and even the eye, a faculty which has given rise to a great variety of experiments, from the days of Charles Bonnet and Spallanzani to those of the present school of Entwickelungsmechanik. Extraordinary as it may appear, considering the abundance of these creatures and the attention they have received from naturalists, it was only in 1880 that their mode of fecundation was correctly ascertained, from observation of the common newt by the Italian zoologist F. Gasco. The amorous games of the newts, so graphically represented by M. Rusconi, had been repeatedly described, and Abbe Spallanzani, as early as 1766, had ascertained the impregnation to be internal. The then current belief that the water served as a vehicle to convey the spermatozoa to the female organs had received a blow on Karl Theodor von Siebold's discovery of a receptaculum seminis in the female, but no satisfactory explanation had been given of the manner in which the spermatozoa reach these pouches. This mystery Gasco succeeded in elucidating in his masterly paper published in 1880, which has since been supplemented by his own investigations on the axolotl, and those of E. Zeller, E. O. Jordan and others on the European and American newts.

All who have kept newts in an aquarium have witnessed the curious antics of the male placing himself before the female and rapidly vibrating his folded tail, or bending his body in a semicircle, as if to prevent her from passing ahead of him. The male then emits, at short intervals, in front of the female, several conical or bell-shaped spermatophores (a gelatinous secretion from the cloaca), adhering to the ground and crowned by a spherical mass of spermatozoa, which the female afterwards gathers in the lips of her cloaca either by mere application or by holding the spermatophore between her hind legs and pressing the mass of spermatozoa into the cloaca, whence they ultimately find their way into the lower part of the oviducts, where the eggs are fecundated as they descend.

The larvae are provided with three pairs of long, fringed, plumelike external gills, which are not lost until the very last stages of the metamorphosis, and, in exceptional. cases are even retained throughout life, the newt breeding in the branchiate condition, as often happens in the axolotl. The fore limbs are developed before the hind limbs.

The genus Molge has a wide distribution, extending over Europe, north-west Africa, south-western Asia, eastern temperate Asia (China and Japan) and North America as far south as southern California and the Rio Grande del Norte. Twenty species are distinguished. The British species are the crested newt (M. cristata), the common newt (M. vulgaris) and the palmated newt (M. palmata). The first is the largest, and measures 4 to 6 in. The skin is more or less rugose, with granular warts, a strong fold extends across the throat, and the male is provided with a very high dentate dorsal crest which is interrupted over the sacral region; the upper parts are dark, with more or less distinct black spots; the sides are speckled with white, and the lower parts are yellow or orange, spotted or marbled with black; a silvery stripe adorns the side of the tail in the male. The common and the palmated newts are smaller, 2 to 4 in. in length, and have a smooth skin. The dorsal crest of the male is high and festooned in the former, low and straight-edged in the latter; during the breeding season the feet of the common newt are lobate like a grebe's, whilst they are webbed like a duck's in the palmated newt, which is further distinguished in having the tail truncate and terminating in a filament.

It is a remarkable fact that, although related so closely and occurring so frequently together in pools of small extent, the common and palmated newts are not known ever to produce hybrids, whilst the crested newt, when coexisting (in some parts of France) with a south-western ally, the beautiful Molge marmorata, to which it is by no means more nearly akin than are the two above-named species to each oth r, regularly gives rise to the form known as M. blasii, which has been proved to be a cross between M. cristata and M. marmorata. Principal references: G. A. Boulenger, Catalogue of Batrachia Gradientia s. Caudata (1882); J. de Bedriaga, Lurchfauna Europas, II. Urodela (1897); F. Gasco, "Sviluppo del Tritone alpestre," Ann. Mus. Geneva, xvi. (1880); E. Zeller, "Befruchtung bei den Urodelen," Z. Wiss. Zool. xlix. (1890) and li. (1891); M. Rusconi, Amours des Salamandres aquatiques (1821); W. Wolterstorff, "Ober Triton blasii," Zool. Jahrb., Syst., xix. p. 647 (1904).


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Wiktionary

Up to date as of January 15, 2010
(Redirected to newt article)

Definition from Wiktionary, a free dictionary

Contents

English

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Wikipedia

Etymology

From the older forms ewt, from euft, from eft, Old English efete. The n comes from hearing “an ewt” as “a newt”; compare apron, nickname, orange, daffodil, and, for a similar phenomenon, trickle.

Pronunciation

Noun

Singular
newt

Plural
newts

newt (plural newts)

  1. a small lizard-like amphibian in the family Salamandridae that lives in the water as an adult.

Synonyms

  • salamander
  • eft (archaic or dialect, or used for some varieties)

Translations

Related terms

See also

Anagrams

  • Anagrams of entw
  • went

Simple English

Newts
File:Smooth
Smooth Newt (Triturus vulgaris)
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Lissamphibia
Order: Urodela/Caudata
Family: Salamandridae
colouration which warns predators of its highly toxic skin.]]

Newts are small amphibians, a kind of salamander. They are found in North America, Europe, and North Asia.

Contents

Life cycle

Their mother lays eggs and leaves them. Tadpoles are born from those eggs.

Newts have three life stages. First as a tiny aquatic larva, which gradually undergoes metamorphosis. Then they leave the water for a year as a juvenile called an eft. They go back in the water to breed as adults.

In some species the adults stay in water for the rest of their lives. Others are land-based, but return to water each year to breed.

Defences

Many newts produce toxins in their skin secretions as a defence against predators. They have bright skin colours as a warning to other animals.

Taricha newts of western North America are particularly toxic; the Rough-skinned newt Taricha granulosa of the Pacific Northwest produces more than enough tetrodotoxin to kill an adult human. Recently, a 29-year-old man in Coos Bay, Oregon, who had been drinking heavily, swallowed a rough-skin newt for a dare; he died later that day despite hospital treatment.[1]

Most newts can be safely handled, provided that the toxins they produce are not ingested or allowed to come in contact with mucous membranes, or breaks in the skin.[1] After handling, proper hand-washing techniques should be followed due to the risk from the toxins they produce and bacteria they carry, such as salmonella.[2][3] It is illegal to handle or disturb Great Crested Newts in the UK without a licence.[4]

Are newts a related group?

The term "newt" has traditionally been used as a functional term for salamanders living in water, and not a systematic unit. The relationship between the genera has been uncertain, though they may be a natural systematic unit. Newer molecular analysis tend to suggest they actually do form a clade.[5][6][7] Newts only appear in one subfamily of salamanders, the Pleurodelinae (of the family Salamandridae).[8] However, some of the genera sometimes listed as Pleurodelinae are not newts (Salamandrina and Euproctus).

References

  1. 1.0 1.1 see caudata.org Accessed 2007-11-28
  2. Salmonellosis - Reptiles and Amphibians Accessed 2007-11-28
  3. CDC MMWR: Reptile-Associated Salmonellosis: Selected States, 1998-2002 Accessed 2007-11-28
  4. bbc.co.uk Factfile 479 Accessed 2007-11-28
  5. Titus T.A. & A. Larson 1995. A molecular phylogenetic perspective on the evolutionary radiation of the salamander family Salamandridae. Systematic Biology 44, 125-151.
  6. Steinfartz S. S. Vicario, J.W. Arntzen & A. Caccone 2006. A Bayesian approach on molecules and behavior: reconsidering phylogenetic and evolutionary patterns of the Salamandridae with emphasis on Triturus newts. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution
  7. Weisrock D.W. et al 2006. A molecular assessment of phylogenetic relationships and lineage accumulation rates within the family Salamandridae (Amphibia, Caudata). Molecular Phylogenetics and Evolution 41, 368-383.
  8. Larson A, Wake D. & Devitt T. 2007. Salamandridae, newts and "true salamanders". Tree of Life on-line project [1]
Look up Salamandridae in Wikispecies, a directory of species








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