Plethodontidae

These special salamanders do not have lungs.

Instead, they breathe through their skin. They also breathe through the inside of their mouths. To stay wet, they have tiny grooves on their bodies.

Wet skin helps them get the air they need. Some of these animals can grow quite large. They use very fast tongues to catch food. Many of them live on land. Their babies hatch as tiny, full adults. There are over 500 kinds of these animals. They are a very successful group.

Lungless salamanders are a very large family of animals.

There are over 500 different species. Most live in the Western Hemisphere. This includes places from Canada to Brazil. A few live in Europe and South Korea.

These animals are special because they lack lungs. Instead, they use their skin to breathe. They also breathe through the lining of their mouths. This is called cutaneous respiration. To help this work, they must stay wet. They have tiny grooves on their sides to move water over their skin.

Many of these salamanders live on land. Their babies use direct development. This means they hatch as tiny, full adults. They do not have a stage where they live in water.

They are very good at finding food. Many use a fast tongue to catch prey. Some eat tiny bugs called springtails. This helps them live where other animals cannot. They also have a special slit near their nose. We call this a nasolabial groove. It helps them smell and keeps their nose clean. These clever traits help them succeed in many homes.

Lungless salamanders are a huge family of animals. They belong to a group called Plethodontidae. There are over 500 different species in this family. This makes them the largest group of salamanders in the world. Most of them live in the Western Hemisphere. You can find them from British Columbia down to Brazil.

A few special types live in other places too. One type lives in South Korea. Another lives in Europe, near the Alps and Sardinia.

These animals have a very interesting way of breathing. Most salamanders use lungs to take in air. However, these salamanders lack lungs entirely. They use cutaneous respiration, which means they breathe through their skin. They also use the lining of their mouths to breathe. To make this work, they must stay very wet. They have little grooves on their sides called costal grooves. These grooves help move water over their skin to keep it moist.

Many of these salamanders spend their whole lives on land. Most salamanders start as babies that live in water. But many Plethodontidae use direct development. This means the babies hatch as tiny, fully-formed adults. They do not need a water stage to grow up. This helps them live in many different land habitats. Because they can live in so many places, they have become very successful. They can even be the most common animals in some areas. For example, one forest district has 1.88 billion southern redback salamanders.

Scientists have studied these animals for a long time. We know they split from a group called Amphiumidae a long time ago. This happened around the K-Pg boundary. We have even found fossils of them in amber. One fossil is from a place called the Dominican Republic. This shows they were in the Caribbean a long time ago.

They also have a special tool for smelling. It is a vertical slit near the nose called a nasolabial groove. This groove helps them smell and keeps their noses clean from water.

These salamanders are great hunters. Many use a fast tongue to catch their food. They can fire their tongues almost as long as their whole body! Some eat tiny bugs called springtails. These bugs are often too small for other animals to eat. This means the salamanders do not have to fight other animals for food. They also have special ways of finding mates. Males use a gland under their chin to share scents. This helps them succeed in their lives on land.

Plethodontidae is a large family of salamanders commonly known as lungless salamanders. This family is the most diverse group of salamanders in existence. There are over 500 different species within this family. Most species live in the Western Hemisphere. They can be found from British Columbia in the north down to Brazil in the south. Only two groups live in the Eastern Hemisphere. One group, called Speleomantes, lives in Sardinia and mainland Europe south of the Alps. Another group, called Karsenia, lives in South Korea.

These animals are unique because they lack lungs for breathing. Instead, they rely on cutaneous respiration. This means they take in oxygen through their skin and the tissues lining their mouths. To make this work, they must stay very moist. They have special ridges on their sides called costal grooves. These grooves help transport water across the surface of their bodies. This constant moisture allows for continuous gas exchange. Most of their oxygen uptake, between 83% and 93%, happens through this skin method. Interestingly, they actually develop tiny, basic lungs while they are embryos. However, these lungs disappear through a process called apoptosis during their development.

Many plethodontids have a very different life cycle than other salamanders. Most salamanders have an aquatic larval stage where they live in water as babies. Many lungless salamanders use direct development instead. This means the offspring hatch from eggs as fully-formed, miniature adults. This change happened because they became less dependent on water for reproduction. Because they do not need ponds or streams to grow up, they can live in many different land habitats. This ability helped them spread and become very successful. They can even become the most common animals in certain environments. For example, one district of the Mark Twain National Forest has about 1.88 billion southern redback salamanders. This represents roughly 1,400 tons of biomass.

Because they are often small and have low metabolisms, they can eat very tiny prey. They frequently eat springtails, which are often too small for other land animals to hunt. This allows them to fill an ecological niche with very little competition. Many species also have a specialized hyoid apparatus. This is a structure that allows them to use a projectile tongue. They can fire their tongues at high speeds to catch prey. In some cases, the tongue can reach a distance almost as long as the salamander's own body.

Finding a mate involves complex and highly specific courtship rituals. One common behavior is a tail-straddle walk. During this, the female positions her head at the base of the male's tail. The male then deposits a sperm capsule, called a spermatophore, on the ground. The female then moves over the capsule to collect the sperm. During this process, males often use pheromones to encourage the female. Males have a mental gland under their chin that secretes these scents. They may also use enlarged teeth to scratch the female's skin. This allows the pheromones to be absorbed more effectively.

To help with smelling, these salamanders have a special structure called a nasolabial groove. This is a vertical slit located between the nostril and the upper lip. The groove is lined with glands that improve chemoreception, or the ability to sense chemicals. Since they cannot blow air out of their noses to clear them, the groove helps drain water and debris away. The groove is narrow and deep near the nostrils to use gravity for drainage. The glands also secrete a fatty film. This film helps pull water away from the nasal passages due to differences in polarity.

Scientists have traced the history of this family back a long time. Plethodontidae likely split from a group called Amphiumidae around the K-Pg boundary. They began to diversify during the Paleogene period. The family likely originated in North America. We know they were in the Caribbean because of fossils found in Dominican amber.

The family is divided into two main subfamilies: Hemidactyliinae and Plethodontinae. These subfamilies contain about 29 different genera. Some examples include the climbing salamanders and the dusky salamanders. While they are very successful, many species face risks. According to the IUCN Red List, many species are currently listed as vulnerable, endangered, or critically endangered. Protecting their habitats is important for their continued survival.