Animals Wildlife 11 Surprising Facts About Salamanders By Jaymi Heimbuch Writer California Polytechnic State University, San Luis Obispo Jaymi Heimbuch is a writer and photographer specializing in wildlife conservation. She is the author of The Ethiopian Wolf: Hope at the Edge of Extinction. our editorial process Twitter Twitter Jaymi Heimbuch Updated January 21, 2021 Joe McDonald / Getty Images Share Twitter Pinterest Email Animals Wildlife Pets Animal Rights Endangered Species Salamanders are amphibians that look roughly like lizards with their legs and tails but with the addition of blunt, frog-like mouths. There are at least 656 salamander species, with 475 near threatened or worse, according to the IUCN. All salamanders are carnivorous and predominantly nocturnal, most very small. Beyond that, they are very diverse. They don't even share the same breathing apparatus, as some have gills, some absorb oxygen through their skin, and others are lung breathers. Learn more about these animals that can even regrow their limbs and parts of their lungs and brain. 1. The Earliest Salamander Species Lived Before the Dinosaurs Triassurus sixtelae lived 230 million years ago during the Triassic period. A fossil from one of these Triassic-era stem salamanders discovered in Kyrgyzstan in 2020 is the oldest salamander ever found. These ancient amphibians show the early development of salamanders and provide background on the divergence between salamanders and other modern amphibians, such as frogs. Prior to the 2020 discovery, the earliest fossils dating to the Jurassic period were found in China. 2. The Axolotl Retains Juvenile Characteristics aureapterus / Getty Images Unlike most other salamander species, the unique and critically endangered axolotl is pedomorphic, meaning it keeps its juvenile features into adulthood. These neotenic salamanders do not undergo complete metamorphosis; instead, they retain their finned tails and the feathery gill structures on the sides of their heads. While other salamander species grow from aquatic larvae into terrestrial adults, the axolotl spends its entire life under water. The cause of this metamorphic miscarriage is the animal's lack of thyroid-stimulating hormone. 3. North America Has More Than 245 Salamander Species Brian Gratwicke / Flickr / CC BY 2.0 North America is home to more salamander species than any other region on the planet, with likely still more species yet to be discovered. Most of those species are in the United States, with the Appalachian Mountains a particular hotspot of salamander diversity. This rich diversity is seriously threatened, though, by salamander chytrid disease. Imported salamanders in the pet trade, such as fire belly newts, carry bacteria that can wipe out entire species. Prevent the spread by disinfecting cage wastes with bleach and never releasing pets into the wild. Report sick or dead salamanders you encounter. 4. Some Species Grow Longer Than Five Feet Best View Stock / Getty Images Although most salamanders are between two and six inches long, on average, there are several species of giant salamander that are considered the largest amphibians in the world. The near-threatened Japanese giant salamander has been known to grow five feet long, for instance, while the even larger Chinese giant salamander — endemic to rocky mountain streams and lakes in the Yangtze river basin — is able to grow up to six feet long. There are believed to be five distinct giant salamander species, although some could already be extinct. 5. Hellbenders Are North America's Only Cryptobranchidae JasonOndreicka / Getty Images Hellbenders are North America's only Cryptobranchids, the same family that contains the giant salamanders of China and Japan. This near-threatened species is found throughout the Appalachian Mountain range. Hellbenders can grow to 27 inches, but the average is around 17 inches. They have a similar appearance to the mudpuppy, another salamander, except they are larger, have wrinkled skin, have fewer toes, and lack gills. People who catch hellbenders are asked to take a picture, release it, and report it to their state agency. You can also aid in research by reporting it to Purdue University via an online reporting form. 6. Sirens Have Gills and Lungs but No Hind Legs Paul Starosta / Getty Images There's a suborder of salamanders called sirens. But they don't lure you closer with their songs — though two species can produce vocalizations. They have eel-like bodies with tiny vestigial front legs and no hind legs. And also unlike most other salamanders, they have external gills even in adulthood. All sirens are found in the United States. While they are species of least concern, they are locally threatened in some areas. 7. They Hibernate in Cold Weather In areas with cold weather, salamanders hibernate by burying themselves deeply in leaf litter or sinking into the muck at the bottom of streams and rivers. The incredible Siberian salamander has an even more incredible ability to survive cold weather. It can tolerate -58 degrees Fahrenheit for three days and longer periods at temperatures around -31 degrees. The key to success is a gradual descent into freezing temperatures to allow the salamander time to convert the liquid in its body to a form of "antifreeze." In dry periods or droughts, salamanders burrow underground and enter torpor to conserve moisture. This doesn't always work, and salamanders face extinction pressure due to increasing droughts from climate change. 8. They Can Regenerate Limbs and Organs Salamanders can regenerate their limbs, and unlike mammals, do not scar. This ability depends on age and species. An older land-dwelling salamander can take more than a year to regenerate a limb. A young axolotl can regenerate the same limb in as little as 40 days. Not only can salamanders regenerate limbs, but they can also replace damaged parts of their heart, lungs, and brain. 9. They Don't Have Vocal Cords Salamanders don't have vocal cords. Instead, they squeak, click, snap, or make kissing-like noises by snapping their jaws or letting out sharp exhalations when they feel threatened. Mostly, they communicate through touch and chemical signals. Some research suggests that salamanders may communicate with high-frequency clicks, though they don't seem to have the hearing structures necessary to detect those sounds. 10. They Are Keystone Species Salamanders both protect the health of an ecosystem and are a habitat barometer. As a keystone species, they are often the most numerous predator eating the mosquitos, insects, and other pests, including shrews. They also serve as food for larger predatory species. They build burrows aerating the soil for plants, and those burrows serve as home to other species. Salamander populations reflect ecosystems' health and serve as an early warning system when they decline due to pollutants like PCBs and heavy metals. Because they react so early to those changes, researchers are aware of problems before they filter up to larger species of both plants and animals, including humans. 11. Their Greatest Enemy Is Humans Katie O'Donnell / USGS / Public domain Humans are the greatest threat to salamanders worldwide. Polluted waterways, clearcutting, development, agriculture, and silviculture harm salamander species globally. Introduced diseases from imported salamanders like Bsal or chytrid fungus threaten endemic species. Other species, like the vulnerable Flatwoods salamander, are harmed by controlled burning. This species buries itself in the summer, which is the natural season for forest fires. However, managed forests are burned in winter, when the salamander and its larva are naturally aboveground. Save the Salamanders Do not buy imported salamanders or release pet salamanders into the wild to prevent the spread of disease.Take part in the Global Amphibian Bioblitz. Leave rocks where they are when you visit streams and rivers. Salamanders use these as homes.Encourage your public officials to use alternatives to road salt to remove snow and ice.