Salamander

Salamanders are a interesting group of amphibians that look a little like small lizards. They have thin bodies, short legs, and tails. You can find them in many places around the world, especially in eastern North America and the Holarctic realm. Some salamanders live only in water, while others live on land but still need places that are moist.

One amazing thing about salamanders is that they can regenerate lost body parts, like legs or parts of their organs, without any scars. Scientists study salamanders to learn how we might heal human injuries in the future.

Many salamanders, especially those in the family Salamandridae, known as newts, have skin that can make a strong poison called tetrodotoxin. These newts often have bright colors to warn other animals that they are poisonous. Salamanders usually lay their eggs in water, and their babies, called larvae, live in water before they grow up.

Etymology

The word salamander comes from Old French salamandre. This came from the Latin word salamandra. The Latin word described a special type of salamander called the fire salamander. The original Greek word salamándra might have come from an even older language.

Description

Salamanders are a group of amphibians that look a bit like lizards. They have thin bodies, short legs, and a tail. Their skin is wet and smooth, but some, like newts, may have bumpy skin. Salamanders can be many colors, from plain to bright, and may have stripes or spots.

Salamanders come in many sizes. The tiniest are minute salamanders, about as long as a crayon. The biggest is the Chinese giant salamander, almost as long as a person. Most are between 10 and 20 cm long. Some salamanders that live in water, like sirens and amphiumas, have small back legs and look like eels. Others use their tails to balance when climbing or to defend themselves. Their skin helps them breathe and can make bad-tasting stuff to keep predators away.

Salamanders can smell and see well, especially at night, and some can see in a special kind of light. They hear with a special system but are mostly quiet. They talk mostly by using smell, and some can make quiet sounds to scare away predators. They breathe in different ways: some use gills when they are young, some keep gills as adults, and others breathe through their skin or simple lungs.

Feeding and diet

Salamanders are opportunistic predators. They will eat almost any food they can catch. Large salamanders, like the Japanese giant salamander, eat crabs, fish, and small animals. Smaller salamanders eat earthworms, flies, beetles, and other tiny creatures. Sometimes, they eat other salamanders when there isn’t much food.

Salamanders have special teeth to catch their food. They also use their sticky tongue to grab prey quickly. Some can stretch their tongue far to catch insects. This helps them live in many places, on land or in water.

Defense

Further information: Antipredator adaptations

Salamanders may look slow and soft, but they have clever ways to stay safe from predators. Their slimy skin makes them hard to grab and can taste bad or be poisonous. When attacked, some salamanders show their poisonous glands, often on their tails, to scare off the danger. Losing a tail helps them escape, and they can grow a new one later.

Some salamanders warn predators with bright colors like yellow, orange, or red. These colors show that they are poisonous. For example, the red eft, the juvenile form of the eastern newt, is very poisonous and is avoided by animals that might try to eat it. Other salamanders mimic these bright colors even if they are not poisonous, tricking predators into staying away. Some salamanders can drop their tails to distract a predator while they escape, and they grow new tails afterward.

Distribution and habitat

Salamanders live in the Holarctic and Neotropical regions. You can find them in North America, England, Scotland, China, and Kazakhstan. They do not live south of the Mediterranean Basin or in parts of South America like the Amazon Basin.

There are about 760 living species of salamander. Many live in the Appalachian Mountains in North America. Some salamanders, like the Anderson's salamander, can live in salty water.

Reproduction and development

Many salamanders find mates using special smells and touches. Most salamanders mate in water, but a few live on land.

Salamanders have different ways of having babies. Some put their sperm inside the female, while others drop it in the water. After this, they lay eggs in water or hidden spots on land. Young salamanders, called tadpoles, usually live in water and have gills like fish. Over time, they change and grow into adults with legs and lungs to live on land. Some salamanders, like the axolotl, keep their gills and stay in water even when they grow up.

Conservation

Many salamander species are in danger because of a disease called chytridiomycosis. People are working to protect them with special plans and groups like the Amphibian Survival Alliance. Some problems come from losing their homes due to deforestation and changes in the weather because of climate change.

Some salamanders, like the Chinese giant salamander, are very rare because people catch them for food and medicine. Scientists are helping these animals by teaching people to take better care of their homes and by breeding them in special places. Other species, such as the hellbender, are also losing numbers, and researchers are finding ways to protect them. For example, a breeding program at the Saint Louis Zoo is helping the hellbender. Scientists are also studying how to help the Ambystoma mexicanum, or axolotl, which faces threats from pollution and loss of habitat. They are looking for ways to keep these animals safe, including freezing sperm for future use.

Taxonomy

The name Urodela comes from Greek words meaning "tail" and "visible." This is because salamanders have long, noticeable tails. A scientist named André Marie Constant Duméril first used this name in 1805.

Salamanders belong to one of three suborders. Scientists may also use the terms Caudata and Urodela when they talk about salamanders. There are ten families of salamanders in the Urodela order.

Phylogeny and evolution

Salamanders are part of a group called amphibians. This group also includes animals like gymnophionans and anurans. Scientists are still learning how these groups are related. Some studies show these groups split from each other and from lobe-finned fish about 360 million years ago, during the Devonian period.

The earliest salamander-like animals lived in the Triassic period in places like Kyrgyzstan. These ancient salamanders looked a bit like today's salamanders but lacked some features that all current ones have. Today, there are two main groups of salamanders: the Cryptobranchoidea, which includes large salamanders like the giant salamander, and the Salamandroidea, which includes most other living salamanders. Fossils of both groups have been found from the Middle to Late Jurassic period in China. By the Upper Cretaceous period, most salamander families we know today likely existed.

Genome and genetics

Salamanders have very large genomes, ranging from 14 Gb to 120 Gb, which is much bigger than the human genome. For example, the genomes of Pleurodeles waltl (20 Gb) and Ambystoma mexicanum (32 Gb) have been studied.

These large genomes affect how salamanders live. They have a slower metabolism, a weaker heart, and a simpler brain. Because of this, salamanders can regrow parts of their bodies, such as their faces, eyes, and even parts of their spinal cord and brain. This makes them very special in scientific research.

In human society

Main article: Cultural depictions of salamanders

Salamanders have appeared in stories and legends for many years, often connected to fire. This idea started because some salamanders live in old, wet wood. When people burned this wood, they would see salamanders trying to escape, leading to beliefs that salamanders had a special link to fire.

Ancient writers like Aristotle and Pliny the Elder shared tales about salamanders being so cold that they could stop fire. Some even believed salamander skin could make clothes that would not burn. Many cultures created myths about salamanders over time.

Salamanders are also important in science. Scientists study animals like the axolotl to understand how they can grow back lost body parts, such as limbs. This research helps scientists learn ways to help humans heal and recover from injuries.