Newts are amphibians found across North America, Europe, North Africa, and Asia, known for their ability to thrive in both aquatic and terrestrial environments. They exhibit remarkable adaptations that allow them to transition between water and land throughout their lives.
Adapting to Water: How Newts Breathe Aquatically
Adult newts primarily breathe underwater through their skin, a process known as cutaneous respiration. Their thin, moist skin, rich in blood vessels, allows dissolved oxygen from the water to pass into their bloodstream while carbon dioxide is released. This permeable skin enables some newts to absorb up to 85-90% of their oxygen needs directly from the water. The effectiveness of this skin breathing relies on well-oxygenated, clean water.
Some newt species also utilize the moist lining of their mouth and throat, a method called buccopharyngeal respiration, to absorb dissolved oxygen. While adult newts can remain submerged for extended periods, they often need to surface occasionally to gulp air, especially if water oxygen levels are low or during periods of high activity.
Life on Land: Newt Terrestrial Respiration
When newts transition to a terrestrial environment, their primary breathing method shifts to small, sac-like lungs. These lungs function similarly to those of other land vertebrates, allowing newts to take in atmospheric oxygen. Their skin also continues to play a significant role in gas exchange even when they are out of the water.
The skin’s ability to facilitate gas exchange on land depends on it remaining moist. This moist skin helps absorb oxygen and release carbon dioxide, supplementing the oxygen uptake provided by the lungs. While lungs become the main respiratory organ for efficient oxygen intake in air, their permeable skin still acquires some oxygen, particularly in damp conditions.
The Newt’s Dual Life: Habitat and Life Cycle
Newts exhibit a biphasic life cycle that necessitates their diverse breathing adaptations. Their life begins as aquatic larvae, which possess feathery external gills efficient at extracting dissolved oxygen from freshwater environments such as ponds and streams.
After a period of growth, newts undergo metamorphosis, developing legs and absorbing gills, which are replaced by air-breathing lungs. Many species then transition to a terrestrial juvenile phase, often called an “eft.” During this stage, efts live on land in moist habitats like damp forests, relying on their lungs and skin for respiration.
As adults, many newt species return to water for breeding, though some European species may largely remain terrestrial, only visiting water to reproduce. Adult newts retain their lungs for terrestrial excursions or when aquatic oxygen levels are low, but their skin becomes the primary means of respiration while submerged.