If you spot a small, long-tailed amphibian near a forested pond, you’re probably looking at a salamander or newt.
But what is the difference between a salamander and a newt? And how do you tell them apart?
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On the tree of life, salamanders are a large and diverse group of tailed amphibians. “They are in the order Caudata, which literally means ‘tailed’ in Latin,” said Karen Kiemnek-Tiburzi, an associate professor at California State Polytechnic Institute of Technology, Humboldt, who specializes in salamanders. There are a total of 10 families of salamanders. Newts are a subfamily of the salamander family called Pleurodelinae.
All newts are salamanders, so there are actually no distinct characteristics that distinguish them. But some species in the subfamily Newt have some interesting characteristics, Bergmeyer said. For example, many newts have skin that looks warty and bumpy. In contrast to salamanders’ smooth, slimy skin, “salamanders tend to have rough skin,” Bergmeyer says.
This is probably because newts are the most poisonous salamanders. Their skin contains many poisonous glands. For example, the skin of the rough-skinned newt (Taricha granulosa), which lives in western North America, contains bacteria that secrete tetrodotoxin. This is the same toxin found in Japanese puffer fish, which can be fatal if ingested.
“If you threw it in your mouth, it would be pretty disastrous,” Burgmeyer said.
Additionally, Salamanders generally have a “biphasic” lifestyle, meaning they often begin their lives in water and then move to land, Burgmeier noted. In some newts, this life cycle can be “three-phase.” This means that newts begin their life in water, go through a juvenile “exit” stage when they come onto land, and end their adult life in water.
An example of this is the eastern newt (Notophysicalmus viridescens), a species common in the eastern United States. This newt has distinctive bright orange juveniles that roam the forest floor (called red efts). Cows live on land for about two to three years, with developed lungs and toxins to avoid predators, and eventually metamorphose into aquatic adults.
Interestingly, however, some coastal populations of eastern newts skip the left phase entirely and end up spending their entire lives underwater. And life cycle variation is common between newts and salamanders. Many newts in Europe and Asia have a more traditional biphasic lifestyle rather than triphasic, Burgmeyer said.
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Similarly, not all newts have bumpy, poisonous skin. Many have smooth skin, such as the smooth newt (Lissotriton vulgaris).
One reason for the lack of uniformity in newt characteristics may be that names were not standardized when herpetology began.
“Historically, the term ‘newt’ was used informally as a common name for this species of warty, bumpy species. [salamanders]”Kyemnec Tiburci told Live Science. “But it turns out they aren’t each other’s closest relatives. As the classification of salamanders became clearer throughout the 20th century, scientists classified the warty, lumpy salamanders and their relatives as newts. As a result, today’s subfamily has a mish-mash of characteristics.
Salamander eyes are also full of diversity. There are also lungless salamanders that do not have a larval stage at all. They develop inside eggs. Some salamanders and axolotls never grow beyond the tadpole stage. Around the world, salamander species can range in length from 1 inch (2.5 centimeters) up to 6 feet (1.8 meters).
Salamanders are “really cool,” Bergmeyer said. He studies North America’s largest salamander, the eastern hellbender (Cryptoblankus alleganiensis alleganiensis). Their presence and health can tell scientists a lot about water quality. For small newts and salamanders, they can be important parts of the food chain, feeding on invertebrates and supporting aquatic and terrestrial ecosystems alike, Bergmeyer added.
“There’s a lot going on with salamanders,” Kiemnec-Tiburci said. “Newts are only a small part of the diversity of salamanders.”
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