Phylum: Chordata
Class: Amphibia
Clade: Caudata
Order: Urodela
Class: Amphibia
Clade: Caudata
Order: Urodela
Salamanders are amphibians with lizard-like bodies, blunt snouts, small limbs that protrude at right angles to the body, and the presence of a tail in both larvae and adults. The order Urodela encompasses all 10 extant salamander families. Salamanders come in a variety of sizes and shapes; some have four legs, while others only have two. Some have lungs, some have gills, while yet others breathe via their skin.
Salamandridae members are primarily recognized as newts, and they lack the costal grooves on the sides of their bodies that other families have. Salamanders are members of the order Caudata, which is one of three Amphibia orders, along with Anura (frogs and toads) and Gymnophiona (frogs and toads) (caecilians, which have no legs and resemble large worms). According to the San Diego Zoo, Caudata has nine families, 60 taxa, and over 600 species. Salamanders include newts, mudpuppies, sirens, and Congo eels (amphiumas). Some salamander species have the potent poison tetrodotoxin in their skin; these salamanders are slow-moving and have brilliant warning coloring to warn of their toxicity.
Description
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There are hundreds of distinct varieties of salamanders, all of which come in a variety of sizes. Salamanders range in size from tiny salamanders with a total length of 27 mm (1+18 in) including the tail to the 1.8 m (6 ft) Chinese giant salamander that may weigh up to 65 kg (145 lb). The majority, on the other hand, are between 10 and 20 cm (4 and 8 in) long.
Except in Salamandridae newts, which have velvety or warty skin that is moist and silky to the touch, the skin lacks scales and is moist and smooth. The skin might be dull or vibrant, with stripes, bars, spots, blotches, or dots in a variety of designs. During the mating season, male newts change colors considerably. Cave species with no pigmentation and a transparent pink or iridescent look are found in the dark.
Habitat and Distribution
Salamanders may be found all around the world, but according to the University of Michigan's Animal Diversity Web, the United States contains the most salamander families (ADW). Except for Hynobiidae (Asian salamanders), all known families are located in the United States. Salamanders broke from the rest of the amphibians in the mid-to-late Permian, and they looked a lot like contemporary Cryptobranchoidea members at first.
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| Native distribution of salamanders and newts. (Copyright © - Wikipedia) |
Their lizard-like appearance is due to symplesiomorphy, or the shared retention of the original tetrapod body plan, although they are not related to lizards any more than mammals are. Frogs and toads are their closest cousins in Batrachia. Salamander fossils dating back to the middle Jurassic era, roughly 164 million years ago, have been discovered in geological layers in China and Kazakhstan.
Salamanders are exclusively found in the Holarctic and Neotropical zones, with the exception of the Mediterranean Basin, the Himalayas, and the Amazon Basin in South America. They do not extend north of the Arctic tree line, with the northernmost Asian species, Salamandrella keyserlingii, found in the Siberian larch forests of Sakha, and the most northerly North American species, Ambystoma laterale, reaching no further north than Labrador and Taricha granulosa not beyond the Alaska Panhandle. Salamanders come in 760 different species. North America is home to one-third of all known salamander species. The Appalachian Mountains, where the Plethodontidae are considered to have evolved in mountain streams, contain the largest concentration of them.
The majority of species, with a few exceptions, dwell in humid woods. The Iranian harlequin newt dwells in western Iran's Zagros Mountains, where water is only available for three or four months of the year. During the wet season, it mates and eats, then rests in a burrow during the dry season.
Reproduction
Because many salamanders lack vocalizations and the sexes in most species appear identical, they rely on smell and tactile clues to identify possible mates, and sexual selection occurs. Pheromones are generated by the abdominal gland in men and the cloacal glands and skin in both sexes and play a vital role in the process. Males have been known to use their snouts to investigate possible mates. Males of Triturus spp., Old World newts, are sexually dimorphic and exhibit in front of females. In some Plethodont species, visual signals are also regarded to be crucial.
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| A moment of a salamander pair mating. (Copyright © - mindenpictures.com) |
In around 90 percent of all organisms, fertilization is internal. The male normally drops a spermatophore on the ground or in the water depending on the species, and the female takes this up with her vent. The spermatophore consists of a packet of sperm supported on a conical gelatinous base, and its deposition and collecting are frequently accompanied by complex wooing activity. The spermatozoa enter the cloaca and go to the spermatheca, one or more chambers in the cloaca's ceiling, where they are kept for often long periods until the eggs are deposited. External fertilization is used instead in the most primitive salamanders, such as Asiatic salamanders and gigantic salamanders. In a reproductive process similar to that of normal frogs, the male discharges sperm onto the egg mass in these species. In some species, the females keep the eggs inside her body until they hatch into larva bodies or fully developed juveniles.
Diet and feeding
Salamanders are predators who take advantage of opportunities. This implies they eat meat rather than plants. Worms, slugs, and snails are among their favorite slow-moving prey. Fish, tiny crustaceans, and insects are eaten by some of the bigger species. Frogs, mice, and even other salamanders are eaten by some salamanders. They aren't picky about what they eat and will eat practically any creature of a suitable size. Crabs, fish, small animals, amphibians, and aquatic invertebrates are eaten by large species like the Japanese giant salamander (Andrias japonicus).
The upper and lower jaws of most salamander species contain tiny teeth. Even the larvae of salamanders, unlike frogs, have these teeth. Many salamanders have tooth patches linked to the vomer and palatine bones at the roof of the mouth, which aid in the retention of prey. Throughout the animal's life, all types of teeth are resorbed and replaced at regular periods. A terrestrial salamander captures its food by flicking out its sticky tongue in less than a half-second motion. The tongue is linked anteriorly to the mouth floor in certain species, whereas it is fixed on a pedicel in others. Because an aquatic salamander's tongue is devoid of muscles, it uniquely grabs its prey. It takes the food item with its teeth and feeds in a sort of inertial manner. Tossing its head around, pulling water in and out of its mouth quickly, and snapping its jaws are all used to rip and macerate the prey, which is subsequently ingested.
Type/Species Of Some Salamanders
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| EASTERN HELLBENDER (Cryptobranchus alleganiensis alleganiensis ) |
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| MUDPUPPY ( Necturus maculosus maculosus ) |
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| JEFFERSON SALAMANDER ( Ambystoma jeffersonianum ) |
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| SPOTTED SALAMANDER ( Ambystoma maculatum ) |
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| MARBLED SALAMANDER ( Ambystoma opacum) |
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| RED-SPOTTED NEWT ( Notophthalmus viridescens viridescens ) |
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| GREEN SALAMANDER ( Aneides aeneus ) |
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| NORTHERN DUSKY SALAMANDER ( Desmognathus fuscus fuscus ) |
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| APPALACHIAN DUSKY SALAMANDER ( Desmognathus monticola monticola ) |
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| MOUNTAIN DUSKY SALAMANDER ( Desmognathus ochrophaeus ) |
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| NORTHERN TWO-LINED SALAMANDER ( Eurycea bislineata bislineata ) |
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| LONGTAIL SALAMANDER ( Eurycea longicauda longicauda ) |
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| NORTHERN SPRING SALAMANDER ( Gyrinophilus porphyriticus porphyriticus ) |
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| FOUR-TOED SALAMANDER ( Hemidactylium scutatum ) |
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| REDBACK SALAMANDER ( Plethodon cinereus ) |
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| SLIMY SALAMANDER ( Plethodon glutinosus glutinosus ) |
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| WEHRLE'S SALAMANDER ( Plethodon wehrlei ) |
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| NORTHERN RED SALAMANDER ( Pseudotriton ruber ruber ) |
Conservation status
Hundreds of species are included on the Red List of Threatened Species by the International Union for Conservation of Nature (IUCN). While some species are classified as Least Concern for extinction due to stable populations, the majority of the species on the list are vulnerable, endangered, or critically endangered.
Because the species is highly fragmented and the population is on the decline, the blunthead salamander, located in a restricted region of northern Mexico, is designated as critically endangered. There is currently no estimate of the population. Similarly, Anderson's salamander, which dwells in a lake in northwestern Mexico, is critically threatened to owe to pollution.
As a result of climate change, several salamander species are diminishing from generation to generation. According to University of Maryland researchers, salamanders in the Appalachian Mountains are diminishing as the local environment becomes hotter and drier, forcing them to expend more energy.
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