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42-416: The initial site, discovered in 1975 by Klaus Müller and his assistants, exceptionally preserves soft-bodied organisms, and their larvae , who are preserved uncompacted in three dimensions. The fossils are phosphatized and silicified , thus the delicate chitinous cuticle and soft parts are not affected by acids, which act upon the limestone nodules within which the fossils have survived. Acids dissolve

84-607: A decrease in corticosterone and aldosterone , hormones produced by the adrenal gland and important for stress response. Although some species, such as the rough-skinned newt ( Taricha granulosa ) and Eastern newt ( Notophthalmus viridescens) in North America or the smooth newt ( Lissotriton vulgaris ) in Europe, are still relatively common, populations of newts throughout their distribution range suffer from habitat loss , fragmentation , and pollution . This affects especially

126-583: A distinct environment, larvae may be given shelter from predators and reduce competition for resources with the adult population. Animals in the larval stage will consume food to fuel their transition into the adult form. In some organisms like polychaetes and barnacles , adults are immobile but their larvae are mobile, and use their mobile larval form to distribute themselves. These larvae used for dispersal are either planktotrophic (feeding) or lecithotrophic (non-feeding) . Some larvae are dependent on adults to feed them. In many eusocial Hymenoptera species,

168-449: A heavy metal released into the environment from industrial and consumer waste, has been shown to be detrimental to the Italian crested newt even at concentrations below Italian and European thresholds, by disrupting the activity of the adrenal gland . In experiments allowing Italian crested newts to be exposed to nonylphenol , an endocrine disruptor common in leakage from sewers, there was

210-488: A loss of motor control: After only 22% water weight loss, newts in the aquatic phase lost their ability to remain upright and mobile. However, after adaptation to a terrestrial phase, they could lose 30% before a loss of motor control was recorded. Newts in the terrestrial phase were found to dehydrate much quicker than newts in the aquatic phase, but conversely, during rehydration, dehydrated terrestrial animals will go through water gain 5x faster than dehydrated newts that are in

252-594: A temperature range that exists outside the predator's preferred temperature range. Larvae that are in the metamorphosizing stage tend to prefer warmer temperatures than those in the stage following metamorphosis. Therefore, the larvae in this stage will undergo a much more precise thermoregulation process than those in the intermediate stage. Reproductive females of the Italian crested newt were shown to regulate their body temperature more precisely and prefer higher temperatures than non-reproductive females and males. The newt

294-442: Is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects , some arachnids , amphibians , or cnidarians typically have a larval phase of their life cycle . A larva's appearance is generally very different from the adult form ( e.g. caterpillars and butterflies ) including different unique structures and organs that do not occur in

336-761: Is based on Antonio Berlese classification in 1913. There are four main types of endopterygote larvae types: Newt 14–17 extant and six fossil genera, see text A newt is a salamander in the subfamily Pleurodelinae . The terrestrial juvenile phase is called an eft . Unlike other members of the family Salamandridae , newts are semiaquatic , alternating between aquatic and terrestrial habitats. Not all aquatic salamanders are considered newts, however. More than 100 known species of newts are found in North America, Europe, North Africa and Asia. Newts metamorphose through three distinct developmental life stages: aquatic larva , terrestrial juvenile (eft), and adult. Adult newts have lizard -like bodies and return to

378-462: 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"). Collective nouns for newts are flotilla and armada. Newts are found in North America, Europe, North Africa and Asia. The Pacific newts ( Taricha ) and the Eastern newts ( Notophthalmus ) with together seven species are

420-474: Is not unanimous. The term "newt" has traditionally been seen as an exclusively functional term for salamanders living in water, and not a clade . Phylogenetic analyses have however shown that species in the Salamandridae traditionally called newts do form a monophyletic group . Other, more distantly related salamander families also contain fully or in part aquatic species, such as the mole salamanders ,

462-637: Is presumed to be derived from fecal pellets. The Orsten fauna has improved our understanding of metazoan phylogeny and evolution , particularly among the arthropods , thanks in part to unique preservation of larval stages. The Orsten sites reveals the oldest well-documented benthic meiofauna in the fossil record. For the first time, fossils have been found of tardigrades ("water bears") and apparently free-living pentastomids . The Cambrian strata consist of alum shales with limestone nodules (the Alum Shale Formation ), which are interpreted as

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504-593: Is regarded as an ideal vertebrate model for investigating the mechanism(s) controlling the transition from mitosis to meiosis during spermatogenesis . In the male newt Cynopa pyrrhogaster , this transition was shown to involve expression of PCNA , a DNA polymerase delta auxiliary protein involved in DNA replication and DNA repair , as well as DMC1 protein, a marker for genetic recombination activity. Larvae, with their great number of lamellae in their gills, are more susceptible to pollutants than adults. Cadmium ,

546-409: Is the ability to release stored erythrocytes when needed, for example under hypoxia . Spleen size can increase as the temperature declines for adults – in larvae, there is no dramatic change in spleen size. During hibernation, an increase in liver pigment cells allows for storage of oxygen, as well as other important ions and free radicals. In experiments, dehydrated eastern newts were prone to

588-511: Is ultimately cognate with Greek ὄφις "snake," from Proto-Indo-European *h₁ogʷʰis ). Latin had the name stellio for a type of spotted newt, now used for species of the genus Stellagama . Ancient Greek had the name κορδύλος , presumably for the water newt (immature newt, eft). German has Molch , from Middle High German mol , wikt:olm , like the English term of unknown etymology. Newts are also known as Tritones (viz., named for

630-737: The Proteidae , or the Sirenidae . Classification of all genera of the Pleurodelinae subfamily after Pyron and Weins, revised by Mikko Haaramo. Pleurodeles [REDACTED] Echinotriton Tylototriton [REDACTED] Notophthalmus [REDACTED] Taricha [REDACTED] Lissotriton [REDACTED] Neurergus Ommatotriton Calotriton Triturus [REDACTED] Euproctus Ichthyosaura Laotriton Pachytriton Cynops [REDACTED] Paramesotriton Phylogenetic analyses estimated

672-765: The smooth newt and palmate newt are not listed, the sale of either species is prohibited under the Wildlife and Countryside Act, 1981. 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 : The remaining European species are listed as "protected fauna species" under appendix III. 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

714-555: The Northern Hemisphere) is in June and July. A single newt female can produce hundreds of eggs. For instance, the warty newt can produce 200–300 eggs (Bradford 2017). 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

756-484: The Pacific Northwest used the toxin to poison their enemies. However, the toxins are only dangerous if ingested or otherwise enter the body; for example, through a wound. Newts can safely live in the same ponds or streams as frogs and other amphibians or be kept as pets. The only predators of Taricha newts are garter snakes , some having developed a resistance to the toxin. Most newts can be safely handled, provided

798-573: The UK have taken steps to halt their declines. 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’ Although the other UK species,

840-401: The adult form. Their diet may also be considerably different. In the case of smaller primitive arachnids, the larval stage differs by having three instead of four pairs of legs. Larvae are frequently adapted to different environments than adults. For example, some larvae such as tadpoles live almost exclusively in aquatic environments, but can live outside water as adult frogs . By living in

882-729: The aquatic breeding sites they depend on, but also their land habitats. Several species, such as the Edough ribbed newt ( Pleurodeles poireti ), Kaiser's spotted newt ( Neurergus kaiseri ), or the Montseny brook newt ( Calotriton arnoldi ) are considered threatened by the IUCN , and the Yunnan lake newt is an example of a newt species that has gone extinct recently. Some newt populations in Europe have decreased because of pollution or destruction of their breeding sites and terrestrial habitats, and countries such as

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924-579: The aquatic phase. In the Italian crested newt, it was shown that during winter months, prolactin is released into the circulatory system, which drives the newts into the aquatic environment and reduces the active transport of sodium ions. In contrast to prolactin, which decreases osmotic permeability, vasotocin increases the permeability and is secreted during the summer months. Arginine vasotocin not only increases cutaneous water permeability, but promotes increased cutaneous blood flow. Thermoregulation, in combination with seasonal acclimation , describes

966-579: 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. The cells at the site of an injury have the ability to un differentiate , reproduce rapidly, and differentiate again to create a new limb or organ. One hypothesis is that the undifferentiated cells are related to tumor cells, since chemicals that produce tumors in other animals will produce additional limbs in newts. The main breeding season for newts (in

1008-409: 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 larvae , 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 amphibian larvae. During the subsequent few months,

1050-495: The land. Conversely, most European species live their adult lives on land and only visit water to breed. 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

1092-553: The larva being called "water-eft" and the mature form "land-eft" well into the 18th century, but the simplex "eft" as equivalent to "water-eft" has been in use since at least the 17th century. Dialectal English and Scots also has the word ask (also awsk , esk in Scots ) used for both newts and wall lizards , from Old English āþexe , from Proto-Germanic *agiþahsijǭ , literally "lizard-badger" or "distaff-like lizard" (compare German Eidechse and Echse , both "lizard;" *agi-

1134-407: The larvae are fed by female workers. In Ropalidia marginata (a paper wasp) the males are also capable of feeding larvae but they are much less efficient, spending more time and getting less food to the larvae. The larvae of some organisms (for example, some newts ) can become pubescent and do not develop further into the adult form. This is a type of neoteny . It is a misunderstanding that

1176-519: The larvae undergo metamorphosis , during which they develop legs, and the gills are absorbed and replaced by air-breathing lungs. Some species, such as the North American newts, also become more brightly colored during this phase. Once fully metamorphosed, they leave the water and live a terrestrial life, when they are known as "efts." Only when the eft reaches adulthood will the North American species return to live in water, rarely venturing back onto

1218-520: The larval form always reflects the group's evolutionary history . This could be the case, but often the larval stage has evolved secondarily, as in insects. In these cases , the larval form may differ more than the adult form from the group's common origins. Within Insects , only Endopterygotes show complete metamorphosis, including a distinct larval stage. Several classifications have been suggested by many entomologists , and following classification

1260-452: The limestone, revealing the microfossils in a recovery process called "acid etching". To recover the fossils, more than one and a half tons of Orsten limestone have been dissolved in acid, originally in a specifically designed laboratory in Bonn , more recently moved to Ulm . The insoluble residue is scanned by electron microscope . The phosphorus used to replace the fossils with calcium phosphate

1302-505: The major mechanisms of how newts, as ectotherms cope with the changing temperatures existing in their environments. This regulation is most often achieved through behavioral thermoregulation. They are thermoconformers , which means they will acclimate to their surrounding environmental temperatures. When there is a large range of environmental temperatures, newts are insensitive to a thermal gradient profile . To escape predators, newt larvae have been found to shift their microhabitat to

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1344-517: The mythological Triton ) in historical literature, and "triton" remains in use as common name in some Romance languages, such as Spanish and Romanian, but as well as in Greek, Russian, and Bulgarian. 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. Tschudi's Pleurodelinae

1386-510: The need of blood cells. In T. carnifex , around two weeks after anemia is induced, the newts produced a mass of cells that helps to revitalize the already circulating red blood cell mass. Adult crested newts ( Triturus cristus ) were found to breathe mainly via the skin but also through the lungs and the buccal cavity . Lung breathing is mainly used when there is a lack of oxygen in the water, or at high activity such as during courtship, breeding, or feeding. A form of compensatory respiration

1428-540: The only representatives in North America, while most diversity is found in the Old World: In Europe and the Middle East, the group's likely origin, eight genera with roughly 30 species are found, with the ribbed newts ( Pleurodeles ) extending to northernmost Africa. Eastern Asia, from Eastern India over Indochina to Japan, is home to five genera with more than 40 species. Newts are semiaquatic , spending part of

1470-462: The origin of the newt subfamily in the Late Cretaceous to Eocene . Several fossil salamanders have also been referred to the Pleurodelinae, including: The heart of newts, like that of most amphibians, consists of two atria and one ventricle. Blood flows from the anterior and posterior caval veins into the right atrium; blood that entered the heart from the left atrium is then expelled out of

1512-644: The products of an oxygen-depleted ("dysoxic") marine bottom water habitat of a possibly offshore seashelf at depths of perhaps 50–100 m. The bottom was rich in organic detritus, forming a soft muddy zone with floc in its surface layer. Other Orsten-type preservation fauna have been found in Nevada, eastern Canada, England, Poland, Siberia, China and the Northern Territory of Australia. Based on data from C.O.R.E website. Larva A larva ( / ˈ l ɑːr v ə / ; pl. : larvae / ˈ l ɑːr v iː / )

1554-438: The toxins they produce are not ingested or allowed to come in contact with mucous membranes or breaks in the skin. Newts form one of three subfamilies in the family Salamandridae , aside Salamandrinae and Salamandrininae . They comprise most extant species in the family, roughly 100, which are classified in sixteen genera: Hypselotriton and Liangshantriton are regarded as separate genera by some authors, but this

1596-503: The ventricle by a thickening of the epicardial layer that protrudes to allow the new vessels to form, and conclude with a regeneration of the entire myocardial wall . In early stages of development in amphibians, ventilator gas transport and hemoglobin gas transport are independent mechanisms and not yet coupled as they are in adulthood. In juvenile amphibians, there is no cardiovascular response in conditions of hypoxia. When newts are induced into anemia, they are able to respire without

1638-428: The ventricle. Newts do not have a coronary artery on the ventricle, due to circulation that is found in the conus arteriosus . Newts contain a special circulatory adaptation that allows them to survive ventricular penetration : when a newt's ventricle is punctured, the heart will divert the blood directly into an ascending aorta via a duct located between the ventricle and the conus arteriosus. Newts begin to regenerate

1680-463: The water every year to breed, otherwise living in humid, cover-rich land habitats. Newts are threatened by habitat loss , fragmentation and pollution . Several species are endangered, and at least one species, the Yunnan lake newt , has become extinct recently. The Old English name of the animal was efte , efeta (of unknown origin), resulting in Middle English eft ; this word

1722-607: The year in the water for reproduction and the rest of the year on land. While most species prefer stagnant water bodies such as ponds, ditches, or flooded meadows for reproduction, some species such as the Danube crested newt can also occur in slow-flowing rivers. The European brook newts ( Calotriton ) and European mountain newts ( Euproctus ) have even adapted to life in cold, oxygen-rich mountain streams. During their terrestrial phase, newts live in humid habitats with abundant cover such as logs, rocks, or earth holes. Newts share many of

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1764-695: Was transformed irregularly into euft , evete , or ewt(e) . The initial "n" was added from the indefinite article "an" by provection (juncture loss) ("an eft" → "a n'eft" → ...) by the early 15th century. 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). The regular form eft , now only used for newly metamorphosed specimens, survived alongside newt , especially in composition,

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