Salamander

Salamanders are a fascinating group of amphibians that look similar to small lizards, with their slender bodies, short limbs, and long tails. They belong to a special group called the order Urodela, which means "conspicuous tail" in ancient Greek. These creatures are found most often in eastern North America, especially in the Appalachian Mountains, but they also live in parts of Europe, Asia, and North America.

One of the most amazing things about salamanders is their ability to regenerate lost body parts, like limbs, organs, and even parts of their spinal cord—without any scarring! Scientists study salamanders to learn how we might one day help people heal from injuries or diseases. This special power makes them very important in medical research.

Many salamanders have smooth, moist skin that helps them breathe, so they need to live near water or in very damp places. Some kinds of salamanders, especially newts, have bright colors and produce a strong poison called tetrodotoxin to warn predators away. They usually lay their eggs in water, where their babies, called larvae, grow before changing into adult salamanders.

Etymology

The word salamander comes from Old French salamandre, which itself comes from Latin salamandra. This Latin word traces back to the Greek word σαλαμάνδρα salamándra, which was used to describe the fire salamander. The origin of this word before Greek is not certain, and it may come from even older languages.

Description

Salamanders are amphibians that look a bit like small lizards, with slender bodies, short limbs, and tails. Their skin is usually moist and smooth, and can be many colors, from dull to bright. Some salamanders, like newts, have velvety or warty skin.

Salamanders range in size from very small, about as long as a fingertip, to the size of a large fish. They live in many different places, some in water and some on land. Most have four limbs that help them move, and their tails help them balance and swim. Some aquatic salamanders have fewer limbs and look more like eels. Their tails can help them move through water or even climb trees!

Feeding and diet

Salamanders are opportunistic predators and will eat almost any organism of a reasonable size. Large species like the Japanese giant salamander (Andrias japonicus) eat crabs, fish, small mammals, and aquatic insects. Smaller salamanders, such as dusky salamanders in the Appalachian Mountains, eat earthworms, flies, beetles, and other small insects.

Salamanders catch their prey in different ways depending on whether they live on land or in water. Land salamanders flick out their sticky tongue to catch food quickly. Water salamanders use their teeth to grab and hold their prey, shaking their heads to help swallow it. Some salamanders, like sirenids, eat plants and algae instead of animals.

Defense

Further information: Antipredator adaptations

Salamanders may seem slow and vulnerable, but they have several ways to defend themselves from predators. Their slimy skin makes them hard to grab and can taste bad or even be poisonous to attackers. Some salamanders have special glands that can shoot toxic fluid to ward off predators, and others can turn their ribs to poke through their skin as a warning.

Salamanders also use colors to stay safe. Some have bright colors like yellow, orange, or red to show they are poisonous, while others hide with dull colors. If a predator attacks, some salamanders drop their tails to escape, and the tail grows back later.

Distribution and habitat

Salamanders are found in the Holarctic and Neotropical regions. They live in areas north of the Mediterranean Basin, the Himalayas, and the Amazon Basin in South America. The northernmost species live in cold regions like Siberia and Labrador.

There are about 760 living species of salamander, with many found in North America, especially in the Appalachian Mountains. Some salamanders can even live in salty water, which is rare for amphibians.

Reproduction and development

Salamanders have many interesting ways of reproducing. Most species don't use sounds to find mates, and both males and females often look the same. Instead, they use smells and touch to find each other. In some species, males show special behaviors to attract females.

Many salamanders mate in water, though some land-living types do it on land. In most, the male puts special packages of sperm somewhere, and the female picks them up. This sperm is stored until the female lays her eggs. Some salamanders lay many small eggs in ponds, while others lay fewer, larger eggs in hidden spots in streams or on land. A few keep their eggs inside until they hatch.

Young salamanders usually start life in water as larvae with gills. Over time, they change and lose their gills, developing into adults that live on land. Some salamanders, like the axolotl, keep their larval features even as adults, a process called neoteny. This can happen because of their environment or genetics.

Conservation

Salamanders are facing serious threats that have caused their numbers to drop. One big problem is a disease called chytridiomycosis, which has hurt many amphibian species. Scientists think other factors like deforestation, climate change, and habitat loss are also hurting salamander populations.

Some salamanders, like the Chinese giant salamander, are in very danger because people catch them for food and medicine. There are efforts to help these animals, such as breeding them in captivity and teaching people to protect their habitats. Researchers are also studying ways to help salamanders breed in controlled environments, which could be important for saving endangered species.

Taxonomy

The name Urodela comes from Greek words meaning "tail" and "visible," referring to the salamanders' noticeable tails. Different scientists sometimes use the terms Caudata and Urodela in slightly different ways, but this article uses Urodela to describe all salamanders.

Salamanders have ten families grouped into three suborders, with a group called Neocaudata often separating certain families from others.

Phylogeny and evolution

The origins and evolutionary relationships between the three main groups of amphibians — gymnophionans, urodeles, and anurans — are still debated by scientists. Studies suggest that these groups diverged from each other around 360 million years ago, after they branched from lobe-finned fish during the Devonian period.

Early salamander-like creatures appeared during the Middle to Late Triassic period, around 250 million years ago. Fossils from this time, such as Triassurus, show that these ancient animals looked somewhat like modern salamanders but lacked some of the features seen today. By the time of the Upper Cretaceous period, most of the salamander families we know today had probably already evolved.

Genome and genetics

Salamanders have very large genomes, ranging from 14 to 120 billion base pairs—much bigger than the human genome, which is about 3.2 billion base pairs long. Two salamander species, Pleurodeles waltl and Ambystoma mexicanum_, have had their genomes fully mapped by scientists.

These large genomes affect many parts of a salamander’s body. They influence the skeleton and circulatory system, leading to a simpler brain, a weaker heart, and a slower metabolism. One amazing result of their unique genetics is their ability to regrow lost body parts, such as faces, eyes, lungs, and even parts of the spinal cord and brain. This makes them valuable for medical research.

In human society

Myth and legend

Main article: Cultural depictions of salamanders

Salamanders have been part of many legends and stories throughout history, often linked to fire. This idea likely started because some salamanders live in rotting logs or firewood. When the log is placed in a fire, the salamander tries to escape, leading people to believe they were made of flame.

Ancient writers like Aristotle and Pliny the Elder told stories about salamanders being so cold that they could put out fire. Some myths even claimed that salamanders could make cloth that didn’t burn. These stories spread through many cultures over time.

Medical research

Salamanders are very interesting to scientists because they can regrow lost limbs. Researchers study them to learn how new body parts grow and hope to use this knowledge to help humans heal injuries or repair damaged organs. Some salamanders, like the axolotls, have been used in these studies. Scientists also discovered that salamanders can work with tiny green algae, which might help us understand how to treat certain human diseases.

Brandy

There have been stories about a special type of alcohol called salamander brandy from Slovenia. Some people claimed it had special effects, but later studies showed that these stories were likely made up to trick or harm others.