Newt

This article is about the animal. For other uses, see Newt (disambiguation).
"Eft" redirects here. For other uses, see EFT.
Newt
Kaiser's spotted newt
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Subphylum: Vertebrata
Superclass: Tetrapoda
Class: Amphibia
Subclass: Lissamphibia
Order: Caudata
Family: Salamandridae
Subfamily: Pleurodelinae

A newt is a semiaquatic[1] amphibian of the family Salamandridae, although not all aquatic salamanders are considered newts. Newts are classified as a part of the salamandrid subfamily Pleurodelinae, and can be found in North America, Europe and Asia.

Newts metamorphose through three distinct developmental life stages: aquatic larva, terrestrial juvenile (called an eft[2]), and adult. Adult newts have lizard-like bodies and may be either fully aquatic, living permanently in the water, or semiaquatic, living terrestrially, but returning to the water every year to breed.

Newts are found across Europe, North America, Asia and Japan but a number of populations are threatened due to pollution or destruction of their breeding sites and terrestrial habitats.

Etymology

The Old English name of the animal was efte, efeta (of unknown origin), resulting in Middle English eft; this word was transformed irregularly into euft, evete, or ewt(e). The initial 'n' was added from the indefinite article 'an' by provection (juncture loss) by the early 15th century.[3] The form 'newt' appears to have arisen as a dialectal variant of eft in Staffordshire, but entered Standard English by the Early Modern period (used by Shakespeare in Macbeth iv.1).[4]

The regular form eft, now only used for newly metamorphosed specimens, survived alongside newt, especially in composition, the larva being called "water-eft" and the mature form "land-eft" well into the 18th century, but use of the simplex "eft" as equivalent to "water-eft" has been in use since at least the 17th century.[5]

Dialectal English and Scots also has the word ask (also awsk, esk in Scots[6]) used for both newts and wall lizards, from Old English āþexe, from Proto-Germanic *agiþahsijǭ, literally "lizard-badger" (compare German Eidechse and Echse; *agi- is ultimately cognate with Greek ὄφις, from Proto-Indo-European *ogʷʰis[7]). Latin had the name stellio for a type of spotted newt, now used for species of the Stellagama genus. Ancient Greek had the name κορδύλος, presumably for the water newt (immature newt, eft).[8] German has Molch, from Middle High German mol, olm, like the English term of unknown etymology.

Newts are also known as Tritones (viz., named for the mythological Triton) in historical literature, and "triton" remains in use as common name in some Romance languages, in Greek, and in Russian. The systematic name Tritones was introduced alongside Pleurodelinae by Tschudi in 1838, based on the type genus named Triton by Laurenti in 1768. Laurenti's Triton was renamed to Triturus ("Triton-tail") by Rafinesque in 1815.[9] Tschudi's Pleurodelinae is based on the type genus Pleurodeles (ribbed newt) named by Michahelles in 1830 (the name meaning "having prominent ribs", formed from πλευρά "ribs" and δῆλος "conspicuous").

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,[10] the Pyrenean brook newt (Calotriton sp.); the European brook newt (Euproctus spp.) and the alpine newt (Ichtyosaura alpestris).[11][12]

In North America, the eastern newts (Notophthalmus spp.) include the red-spotted newt (Notophthalmus viridescens), which 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.

In Southeast Asia and Japan, species commonly encountered in the pet trade include the fire belly newts (Cynops spp. and Hypselotriton spp.), the paddle-tail newts (Pachytriton spp.), the crocodile newts (Tylototriton spp.), and the warty newts (Paramesotriton spp.). In the Middle East are the spotted newts (Neurergus spp.).[13]

Characteristics

A red-spotted newt (eft stage) is showing bright aposematic colouration to warn predators of its highly toxic skin.[14]

Newts share many of the characteristics of their salamander kin, Caudata, including semipermeable glandular skin, four equal-sized limbs, and a distinct tail. The newt's skin, however, is not as smooth as that of other salamanders.[15] Aquatic larvae have true teeth on both upper and lower jaws, and external gills.[16] They have the ability to regenerate limbs, eyes, spinal cords, hearts, intestines, and upper and lower jaws. The Japanese fire belly newt can regenerate its eye lens 18 times over a period of 16 years and retain its structural and functional properties.[17] The cells at the site of the injury have the ability to undifferentiate, reproduce rapidly, and differentiate again to create a new limb or organ. One hypothesis is that the undifferentiated cells are related to tumour cells, since chemicals that produce tumours in other animals will produce additional limbs in newts.[18]

Development

Alpine newt larva part-way through metamorphosis

The main breeding season for newts is (in the Northern Hemisphere) in June and July. 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. Fertilized eggs are laid singly and are usually attached to aquatic plants. This distinguishes them from the free-floating eggs of frogs or toads, which are laid in clumps or in strings. Plant leaves are usually folded over and attached 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 are absorbed and replaced by air-breathing lungs.[19] 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".[20] 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.[21]

Toxicity

Taricha newts are known for their toxicity

Many newts produce toxins in their skin secretions as a defence 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, and some Native Americans of the Pacific Northwest used the toxin to poison their enemies.[22] However, the toxins are only dangerous if ingested, and the newts can easily and safely live in the same ponds or streams as frogs and other amphibians, or be safely kept as pets. The only predators of Taricha newts are garter snakes, some having developed a resistance to the poison. Most newts can be safely handled, provided the toxins they produce are not ingested or allowed to come in contact with mucous membranes or breaks in the skin.[22] 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.[23][24] It is, however, illegal to handle or disturb great crested newts in the UK without a licence.[25]

Systematics

About two-thirds of all species of the family Salamandridae, comprising these genera, are commonly called "newts":

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, although they have been suggested to constitute a natural systematic unit and newer molecular analyses tend to support this position.[26][11][27] Newts only appear in one subfamily of salamanders, the Pleurodelinae (of the family Salamandridae),[28] however, Salamandrina and Euproctus, which are sometimes listed as Pleurodelinae, are not newts. 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.[27][29]

Conservation status

China

The Yunnan lake newt is considered extinct.[30]

Europe

Some newt populations in Europe have decreased because of pollution or destruction of their breeding sites and terrestrial habitats, and countries such as the UK have taken steps to halt their declines.[31][32] 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, or to cause them harm or death, or to disturb their habitat in any way. The IUCN Red List categorises the species as ‘lower risk’[21][25] 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.[33]

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:[34]

The remaining European species are listed as "protected fauna species" under appendix III.[35]

As bioindicators

Newts, as with salamanders in general and other amphibians, serve as bioindicators because of their thin, sensitive skin and evidence of their presence (or absence) can serve as an indicator of the health of the environment. Most species are highly sensitive to subtle changes in the pH level of the streams and lakes where they live. Because their skin is permeable to water, they absorb oxygen and other substances they need through their skin. Scientists study the stability of the amphibian population when studying the water quality of a particular body of water.

As pets

Chinese warty newts, Chinese fire belly newts, eastern newts, paddletail newts, Japanese fire belly newts, Chuxiong fire-bellied newts, Triturus species, emperor newts, Spanish ribbed newts (leucistic genes exist), and red-tailed knobby newts are some commonly seen newts in the pet trade. Some newts rarely seen in the pet trade are Rough-skinned newts, Kaiser's spotted newts, Banded newts and Yellow-spotted newts.

References

  1. ↑ "Newt". Merriam-Webster Dictionary. Encylopaedia Britannica. Retrieved 2015-06-24.
  2. ↑ "Newts". Current Biology 15: R42–R44. Jan 2005. doi:10.1016/j.cub.2004.12.049. PMID 15668151. Retrieved 2013-06-06.
  3. ↑ Oxford English Dictionary; Anon. "Online etymological dictionary". Douglas Harper. Retrieved 9 October 2013.
  4. ↑ The Gentleman's Magazine, and Historical Chronicle, Volume 47 (1777), p. 321.
  5. ↑ John Wilkins, An Essay Towards a Real Character, and a Philosophical Language (1668), p. 161. "the water-eft, or newt, is only the larva of the land-eft, as tadpoles are of frogs." Gilbert White, The Natural History and Antiquities of Selborne, in the County of Southampton (1789) p. 50. "the salamandra aquatica of Hay, (the water-newt, or eft,)" Archibald Constable, Constable's miscellany of original and selected publications in the various departments of literature, science, & the arts, Volume 45 (1829), p. 63.
  6. ↑ John Jamieson, An etmological dictionary of the Scottish language (1818)
  7. ↑ Pfeifer, Etymologisches Wörterbuch s.v. Eidechse.
  8. ↑ Henry George Liddell, Robert Scott, A Greek-English Lexicon
  9. ↑ Alain Dubois and Roger Bour, The nomenclatural status of the nomina of amphibians and reptiles created by Garsault (1764), with a parsimonious solution to an old nomenclatural problem regarding the genus Bufo (Amphibia, Anura), comments on the taxonomy of this genus, and comments on some nomina created by Laurenti (1768), Zootaxa 2447 (2010), 1–52.
  10. ↑ "A Newt Tale". Calacademy.org. Retrieved 2013-06-06.
  11. 1 2 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
  12. ↑ 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.
  13. ↑ "Welcome livingunderworld.org - Hostmonster.com". Livingunderworld.org. Retrieved 2013-06-06.
  14. ↑ "Newt Information and Gallery". Theinformationarchives.com. Retrieved 2013-06-06.
  15. ↑ Collins, J. T.; Conant, R.; Stebbins, R. C.; Peterson, R. T. (1999). Peterson First Guide to Reptiles and Amphibians. Houghton Mifflin Harcourt. ISBN 0-395-97195-0.
  16. ↑ Heying, Heather. "Adw: Caudata: Information". Animaldiversity.ummz.umich.edu. Retrieved 2013-06-06.
  17. ↑ "Newts re-grow eye lens 18 times over". COSMOS magazine. 2011-07-13. Retrieved 2013-06-06.
  18. ↑ Archived September 2, 2006, at the Wayback Machine.
  19. ↑ "Amphibians - body, used, water, process, Earth, life, characteristics, form, animals, oxygen, air, plant, change, History, Characteristics, Life cycle, Three major groupings". Scienceclarified.com. 2009-10-13. Retrieved 2013-06-06.
  20. ↑ "Cambridge City Council: Local Nature Reserves". Lnr.cambridge.gov.uk. 2005-07-25. Retrieved 2013-06-06.
  21. 1 2 "BBC Nature - Great crested newt videos, news and facts". Bbc.co.uk. Retrieved 2013-06-06.
  22. 1 2 "Caudata Culture Articles - Newt Toxins". Caudata.org. Retrieved 2013-06-06.
  23. ↑ Salmonellosis - Reptiles and Amphibians
  24. ↑ "CDC MMWR: Reptile-Associated Salmonellosis: Selected States, 1998-2002". Cdc.gov. 2003-12-12. Retrieved 2013-06-06.
  25. 1 2 "Science & Nature - Wildfacts - Smooth newt, common newt". BBC. 2012-04-27. Retrieved 2013-06-06.
  26. ↑ Titus, T. A.; Larson, A. (1995). "A molecular phylogenetic perspective on the evolutionary radiation of the salamander family Salamandridae". Systematic Biology 44: 125–151. doi:10.1093/sysbio/44.2.125.
  27. 1 2 Weisrock, D. W.; Papenfuss, T. J.; Macey, J. R.; Litvinchuk, S. N.; Polymeni, R.; Ugurtas, I. H.; Zhao, E.; Jowkar, H.; Larson, A. (2006). "A molecular assessment of phylogenetic relationships and lineage accumulation rates within the family Salamandridae (Amphibia, Caudata)". Molecular Phylogenetics and Evolution 41: 368–383. doi:10.1016/j.ympev.2006.05.008. PMID 16815049.
  28. ↑ Larson, A, Wake, D., & Devitt, T. (2007): Salamandridae, Newts and "True Salamanders". Tree of Life on-line project
  29. ↑ 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
  30. ↑ Yang Datong, Michael Wai Neng Lau (2004). "Cynops wolterstorffi". IUCN Red List of Threatened Species. Version 2012.2. International Union for Conservation of Nature. Retrieved 1 January 2013.
  31. ↑ "USGS Amphibian Research Monitoring Initiative (Pacific Northwest Region)". Fresc.usgs.gov. 2013-01-30. Retrieved 2013-06-06.
  32. ↑ UK Biodiversity Action Plan Archived October 24, 2007, at the Wayback Machine.
  33. ↑ "Smooth newt videos, photos and facts - Triturus vulgaris". ARKive. Retrieved 2013-06-06.
  34. ↑ "Annexe II: Strictly protected fauna species". Retrieved 2013-06-06.
  35. ↑ "Annexe III: Protected fauna species". Retrieved 2013-06-06.

External links

Look up newt in Wiktionary, the free dictionary.
Look up newt or eft in Wiktionary, the free dictionary.
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