Many people know that most salamanders love to hang around in or near freshwater bodies, such as ponds, lakes, or streams. But have you ever wondered why salamanders need water?
Salamanders need water to keep their skin moist, rehydrate, regulate their temperature, and reproduce.
Salamanders are amphibians, which means they live part of their lives in the water and part on land. Most salamanders are directly dependent on water for part of their life cycle.
Most Salamanders Start Their Lives in the Water
The majority of salamanders go through 3 life stages. Female salamanders lay jelly-covered eggs and attach them to vegetation in breeding bonds.
After a few weeks, tiny aquatic larvae emerge from these eggs.
Larvae are very different from adult salamanders; this is because they’re adapted for a fully aquatic life, while adult salamanders are adapted for a semi-aquatic, or mostly terrestrial life (depending on the species).
The larvae have external feathery gills and live completely in the water, just like frog tadpoles.
Larvae Turn Into Adults
After a few months, to as long as three years in some species, the larvae will go through a process known as metamorphosis and transform into adults.
During metamorphosis, terrestrial (land-dwelling) salamanders will lose their gills and develop strong legs for walking on land.
Many (such as the tiger salamander Ambystoma tigrinum) also develop lungs for breathing air. However, some terrestrial salamanders do not develop any lungs, but instead, develop to breathe through their skin and thin membranes in their mouths and throat.
Most Adult Salamanders Need to Be Near Water to Survive
Although adult salamanders can survive on land, most species still require frequent access to water to survive.
They usually hang around cool, humid, shaded areas near ponds, swamps, streams, lakes, and other water bodies.
Here are 4 reasons why salamanders need water.
1. To Keep Their Skin Moist
Salamanders and other amphibians have unique skin compared to that of many other vertebrates. Their skin is composed of thin membranous tissue that is quite permeable to water and contains a large network of blood vessels.
This permeable skin distinguishes them from mammals, birds, or reptiles.
Permeability relates to how easily a gas or liquid molecule can pass back and forth from the environment into the animal and vice versa.
Typically, the larger the molecule, the more difficult it is to enter the animal through its skin. Amphibian skin is more permeable than that of other vertebrates.
Their membranous skin allows water and respiratory gases to readily diffuse directly down their gradients between the blood vessels and the surroundings.
To efficiently breathe through their skin, salamanders and other amphibians like frogs, have to keep their skin constantly moist by secreting a special mucous coating (which gives them a slimy feeling when touched).
The mucus that salamanders secrete traps moisture next to the skin. This moisture then transfers oxygen into the salamander’s bloodstream and allows carbon dioxide to diffuse out. This process is called cutaneous gas exchange.
Salamanders can only breathe through their skin if the skin stays moist. If it dries up, they can suffocate and die.
For this reason, Salamanders generally need to be near water so they can keep their skin moist, and prevent it from drying out.
2. To Cool down and Escape the Heat
Salamanders are ectothermic or “cold-blooded” animals, which means they cannot regulate their body temperature. Their body temperature changes as the temperature in their surroundings changes.
When it’s warm, their bodies soak up the heat, and their body temperature rises. When it’s cooler, their body temperature falls.
Since salamanders can not generate their own internal heat, they rely on external heat sources such as the sun to keep their bodies at optimal temperatures.
As the temperature changes at different times of day and night, they move around in their environment to regulate their body heat. This is known as “behavioral thermoregulation.”
When their body temperature is low, they move into the sun to warm up, when it is high, they move to the shade or cool water to cool down.
For instance, If a salamander’s body temperature is too hot, it may move to the water to cool down.
The water is cooler than the air and not only cools the salamander through conduction but also rehydrates it, which allows it to use evaporation cooling to stabilize its body temperature.
3. To Keep Themselves Hydrated
Like all living creatures, salamanders need to consume water to survive.
Dehydration can be harmful, and even potentially lethal to most frogs. Their need for water is as critical as their need for food or oxygen–it’s an essential substance, that keeps their bodies working normally.
Salamanders’ bodies need a steady supply of fluids to transport nutrients, eliminate waste, and perform many other important functions.
That said, salamanders and other amphibians do not drink water through their mouths like we do. Instead, they rehydrate by absorbing water across their permeable skin, in a process known as ‘cutaneous absorption’.
Salamanders need to live near bodies of fresh water in which they can soak and lie – to rehydrate.
In rainy weather, it’s common for salamanders to come of out their retreats, and soak in rain puddles on the ground. While they soak in water, they absorb some of the water through their skin and rehydrate.
4. To Reproduce in the Water
The vast majority of salamander species require water to successfully reproduce.
Salamanders typically lay their eggs in shallow, standing, or slow-moving freshwater bodies that are free of predatory fish.
This could be in ponds, lake edges, slow-moving streams, roadside ditches, or even deep tire tracks, but the majority of salamanders very strongly prefer to breed in something called “vernal pools“.
Vernal pools are seasonal pools of water. They are formed when depressions on the ground are filled with water from melting snow and falling rain.
Since they are temporal, they do have fish that could eat the salamander eggs before they hatch, which makes them ideal breeding sites.
The female salamander will fertilize her eggs internally lay egg masses and attach them to submerged vegetation or on the underside of submerged rocks in the pool.
This is often just a few inches below the water’s surface, but occasionally deeper.
If the pool has lots of emergent vegetation, eggs are often deposited in open areas that receive lots of sunlight.
Some Salamanders Can Survive Away From Water
Although most salamanders require access to water, some species, such as the Red-backed salamander (Plethodon cinereus) are entirely land-dwelling and do not need standing water of any kind.
These salamanders usually will not go to water, even to breed, or re-hydrate.
They lay their eggs in moist places on land– and then hatch into young fully developed baby salamanders– which are morphologically similar to the adults. This is known as ‘direct development.’
Red-backed salamanders can re-hydrate entirely by absorbing moisture from moist soil, or any other moist material, such as damp leaf litter.
The lack of a direct dependence on standing water allows Red-backed salamanders to live in fragmented forests, and even in urban areas – without the limitation of a direct dependency on water.
Conclusion
Salamanders are amphibians, and most species are directly dependent on water for part of their life cycle.
Although adult salamanders live mostly terrestrial lives, they still need access to fresh water to survive and thrive.