Salamanders are an order of amphibians (Caudata), characterized by a “dual life”—a transition from an aquatic stage to a terrestrial stage. The simple question of whether a salamander can live in water requires a nuanced answer that depends heavily on the specific species and its developmental stage. While all salamanders are tied to moist environments due to their permeable skin, their relationship with water ranges from fully aquatic to almost entirely terrestrial. Understanding this complexity requires examining their typical life progression and the distinct anatomical features that govern gas exchange and movement in both habitats.
The Standard Amphibious Life Cycle
The typical life trajectory for many salamander species begins entirely underwater, starting with eggs laid in water. These hatch into larvae that are structurally adapted for a submerged existence. Larval salamanders possess external, feathery gills branching from the neck, which are highly efficient at extracting dissolved oxygen from the water column.
These larvae also have a laterally compressed tail with a finned edge, which functions as a paddle for propulsion through the water. During this stage, which can last from a few weeks to several years depending on the species, the young salamander is obligately aquatic. The larval stage is characterized by a reliance on the gills for respiration, with the skin providing supplemental gas exchange.
The transformative process of metamorphosis marks a significant shift, preparing the animal for life outside the water. As the salamander approaches this transition, the external gills begin to regress and are ultimately absorbed. Simultaneously, functional lungs develop internally, and the tail fin is reduced, making the body more suited for terrestrial locomotion.
Upon completing metamorphosis, the juvenile or adult form emerges onto land. Breathing transitions from gills to a combination of lungs and the lining of the mouth and throat, a process called buccopharyngeal pumping. This adult form has fundamentally different physiological requirements and habitat preferences, moving away from the complete dependence on water that defined its youth.
Physical Adaptations for Aquatic Survival
The ability of salamanders to thrive in water is supported by a suite of specialized anatomical and physiological traits. External gills are highly vascularized structures that increase the surface area available for gas exchange in an aqueous environment. In fully aquatic species, or the larval stage of others, these gills may be actively moved by muscles to ensure a constant flow of oxygenated water passes over the respiratory surfaces.
Beyond the gills, the skin plays a significant role through cutaneous respiration—the direct absorption of oxygen and release of carbon dioxide through the moist, permeable skin. This physiological requirement explains why even terrestrial salamanders must remain in cool, damp environments. Drying out would halt gas exchange, which is essential for their survival.
For movement, aquatic salamanders possess a tail morphology optimized for swimming. This tail is often flattened horizontally, giving it a paddle-like shape that generates thrust through side-to-side undulations. Furthermore, some highly aquatic species, such as the Eastern Hellbender, have loose, vascularized folds of skin along their flanks. These folds increase the total surface area for cutaneous respiration, allowing them to absorb nearly all their oxygen directly from the water.
Adult Life History: Terrestrial, Semi-Aquatic, and Fully Aquatic Species
The adult phase of a salamander’s life reveals the full diversity of their relationship with water, resulting in three distinct life history strategies.
Fully Terrestrial Species
The first group is the fully terrestrial species, most notably the Plethodontidae, or lungless salamanders, which represent the largest family. These salamanders have completely lost the ability to breathe with lungs, relying exclusively on cutaneous respiration and the moist lining of their mouth and throat. Many lungless salamanders bypass the aquatic larval stage entirely through direct development, where eggs hatch directly into miniature, terrestrial adults. These species are inextricably bound to damp forest floor habitats and only return to water or very wet substrates for reproduction.
Semi-Aquatic Species
Semi-aquatic species, such as newts, exhibit a complex, multi-stage life cycle. Newts often begin as aquatic larvae, transition to a terrestrial juvenile stage called an eft, and then return to the water as aquatic adults. The terrestrial eft stage can last for several years and is characterized by rough, brightly colored skin for defense. The final adult stage sees them revert to smoother skin and re-develop a paddle-like tail for their permanent habitation in ponds or slow-moving streams.
Fully Aquatic Species
The third group consists of fully aquatic species that never undergo complete metamorphosis, a phenomenon known as neoteny or paedomorphosis. Species like the Axolotl (Ambystoma mexicanum) and the Mudpuppy (Necturus maculosus) retain their external gills, finned tails, and other larval features throughout their entire adult lives. They reach sexual maturity while maintaining this juvenile morphology, making them obligate water dwellers that are incapable of surviving for long periods on land. This retention of larval traits is a specialized adaptation to stable aquatic environments where the terrestrial life stage is not beneficial.