#urodela

Salamanders are capable of regenerating lost limbs as well as other damaged parts of their bodies, including vital organs such as their heart, jaw, and parts of the spinal cord.

Due to their popularity in the pet trade, the Axolotl (Ambystoma mexicanum) is perhaps the most famous salamander. They are paedomorphic, maturing without undergoing metamorphosis into a terrestrial adult form, instead remaining fully aquatic with obvious external gills. They resemble larvae of the occasionally paedomorphic Tiger Salamander (Ambystoma tigrinum). Critically endangered in the wild, they originally inhabited a large lake in the Mexican highlands known as Lake Texcoco, along with a number of smaller, interconnected lakes such as Lake Xochimilco and Lake Chalco, and were abundant enough to form a staple in the Aztec diet. These lakes were mostly drained by Spanish colonists after the conquest of the Aztec Empire, leading to the destruction of most of the Axolotl's natural habitat, which is now largely occupied by Mexico City. Due to continued urbanization in Mexico City, which causes water pollution in the remaining waterways, as well as the introduction of invasive species such as tilapia and perch, the Axolotl is nearly extinct. Six adult Axolotls (including a leucistic specimen) were shipped from Mexico City to Paris in 1863, where French scientists began studying them. They were found to be able to regenerate body parts, could be artificially induced to metamorphosize, and were hybridized with Tiger Salamanders. Their success in scientific research has also led to them being prolific in the pet trade, and one restaurant in Japan even sells fried Axolotls as a menu item. Despite their large population in captivity, these Axolotls are inbred and often contain Tiger Salamander genes, and can not contribute to the tiny population of pure wild Axolotls. Lake Texcoco and Lake Chalco no longer exist, so they are native only to the freshwater lake Xochimilco, which remains a remnant of its former self, existing mainly as canals. Only 2 wild Axolotls were spotted in 2013, after months of searching. Currently, the Lake Texcoco Ecological Park is being established to restore natural spaces to Mexico City, and hopefully provide a home for the Axolotl and other Mexican biodiversity.

The similarly critically endangered Anderson's Salamander (Ambystoma andersoni), from Zacapu Lagoon in the Mexican state of Michoacán, is one of the few species of living amphibians to occur in brackish or salt water.

Salamanders of the family Plethontidae have tongues that reach up to 80% of their body length, are attached to their skeleton, and fire ballistically at prey in less than 20 milliseconds.

Slimy Salamanders (Plethodon glutinosis) do not lay their eggs in water, so they stay near them to keep them from drying out, as well as to defend them from predators.

The largest living lissamphibian is the South China Giant Salamander (Andrias sligoi) (image 2), with the largest known individual having been 1.8 m (5.9 ft) long. It is critically endangered due to habitat loss, pollution, and overcollection, and its use in traditional medicine and status as a delicacy has led to it being farmed for meat. It is hoped that this will take the heat off the wild salamanders, though wild salamanders are still often caught to bolster breeding populations in meat farms. It is unknown if any South China Giant Salamanders still exist in the wild, and those on farms are likely hybridized, as Andrias species are often caught indiscriminately and are able to interbreed. Of the known individuals that survive in zoos, all are males, and are nearing the end of their natural lifespans.

The Eastern Newt (Notophthalmus viridescens) is perhaps best known for its striking, land-dwelling juvenile stage which is colloquially called a Red Eft. Eastern Newts have three stages of life: the aquatic larva/tadpole, the terrestrial Red Eft, and the aquatic adult. Having a terrestrial juvenile stage allows young Eastern Newts to disperse to new ponds. They will spend 2-3 years in the Red Eft stage before choosing a pond and transforming into an adult.

References:

Iturralde-Vinent, M. A., and R. D. MacPhee. "Remarks on the age of Dominican amber." Palaeoentomology 2.3 (2019): 236–240. https://doi.org/10.11646/palaeoentomology.2.3.7

Poinar Jr, G., and Wake, David B. "Palaeoplethodon hispaniolae gen. n., sp. n.(Amphibia: Caudata), a fossil salamander from the Caribbean." Palaeodiversity 8 (2015): 21-29. https://escholarship.org/uc/item/1f381770

Wikipedia contributors. “Bolitoglossa” Wikipedia, 18 Apr. 2024, https://en.wikipedia.org/wiki/Bolitoglossa

Wikipedia contributors. “Palaeoplethodon.” Wikipedia, 20 Nov. 2023, https://en.wikipedia.org/wiki/Palaeoplethodon