Lizards are one of the most adaptable and diverse groups of reptiles in the world. Found across deserts, forests, mountains, and even urban areas, these cold-blooded creatures have evolved unique physical and behavioral traits that help them survive in different environments. But one question often puzzles both reptile enthusiasts and casual observers: can lizards breathe underwater?
At first glance, the idea may seem absurd. Lizards are reptiles, and like most land animals, they breathe air through lungs. However, as we look more closely at certain species and their unusual adaptations, the answer becomes more nuanced and fascinating. Some lizards have evolved survival strategies that allow them to stay underwater for extended periods of time. These adaptations aren’t the same as breathing underwater like fish or amphibians, but they can mimic the effect in remarkable ways.
In this article, we will examine the biological structure of lizards, their respiratory systems, and specific cases where lizards interact with aquatic environments. We’ll also explore an incredible evolutionary feature discovered in recent years that allows one species to remain underwater for long durations. You’ll come away with a deep understanding of how these animals breathe, how they handle water environments, and what science tells us about their limits.
Understanding How Lizards Breathe
To determine whether lizards can breathe underwater, we first need to understand how they breathe above water. Like other reptiles, lizards have lungs, not gills. Their lungs are highly vascularized, meaning they have a dense network of blood vessels that facilitate oxygen exchange. This structure is well-suited for life on land.
Unlike mammals that use a diaphragm to breathe, lizards rely on muscular movements of their chest and ribs. When a lizard inhales, muscles contract to expand the chest cavity, allowing air to flow into the lungs. Exhalation happens when the muscles relax and the air is pushed out.
The key takeaway here is that lizards are air-breathing animals. They cannot extract oxygen directly from water, which would be necessary to truly “breathe underwater.” So does that mean the answer is a firm “no”? Not quite. Some lizards can stay submerged for surprisingly long periods using clever adaptations.
Lung-Based Respiration and Its Limits in Water
A lizard’s lungs cannot function properly if the lizard is fully submerged for extended periods. That’s because there’s no way for the lungs to access oxygen from water. If a lizard stays underwater too long, it will eventually suffocate, just like a human would.
However, lizards can hold their breath and lower their metabolic rate to conserve oxygen. This allows them to remain underwater for longer than one might expect. While this doesn’t qualify as breathing underwater, it’s a crucial mechanism that aids survival.
Why Would Lizards Go Underwater?
Lizards aren’t generally known for swimming or diving, but there are reasons they may enter water. Here are some natural behaviors that involve water:
Escaping predators: Some lizards dive into rivers or ponds to avoid being caught.
Thermoregulation: Water can help regulate body temperature on hot days.
Searching for food: Aquatic insects and small animals may attract certain species.
Territorial reasons: Some lizards may cross water bodies to establish or protect territory.
So although they are not aquatic animals by definition, some lizards come into frequent contact with water.
The Water Anole: A Remarkable Case
In 2020, scientists made a groundbreaking discovery about a species of lizard known as the water anole (Anolis aquaticus), native to Costa Rica. This lizard stunned researchers with its ability to remain submerged for over 16 minutes. But how?
The water anole uses an evolutionary trick that seems almost science fiction: it creates an air bubble that adheres to the top of its head. When submerged, the lizard exhales into this bubble and then re-inhales from it. Essentially, the bubble acts as a rebreather system, allowing the lizard to recycle the same air and extend its time underwater.
This adaptation isn’t true underwater breathing like that of fish, but it mimics the process enough to allow extended submersion. Scientists believe this adaptation evolved as a predator avoidance strategy, giving the water anole a better chance of escaping threats.
How the Rebreathing System Works
To understand this better, let’s break down the process:
−The lizard dives into the water.
−It exhales a bubble that forms over its nostrils and mouth.
−The bubble is held in place by hydrophobic (water-repellent) skin around the head.
−As the lizard stays submerged, it re-inhales the air from the bubble.
−Eventually, the oxygen in the bubble runs low, and the lizard resurfaces.
This form of recycled respiration allows it to stay submerged for minutes at a time. It doesn’t change the basic rule that lizards breathe air, but it showcases a form of evolutionary innovation that simulates breathing in a unique environment.
Other Aquatic Lizards and Their Strategies
The water anole isn’t the only lizard with aquatic behavior. Several other species have developed different tactics to manage short-term submersion:
Basilisk Lizards
Known as the “Jesus lizard,” the common basilisk (Basiliscus basiliscus) can run across the surface of water and is an excellent swimmer. Though it can’t breathe underwater, it can hold its breath for several minutes while hiding below the surface.
Monitor Lizards
Some monitor lizards, like the Asian water monitor (Varanus salvator), are semi-aquatic and capable swimmers. They can dive and remain submerged while foraging or evading predators, though they must return to the surface to breathe.
Marine Iguanas
The marine iguana (Amblyrhynchus cristatus) of the Galápagos Islands dives into the ocean to feed on algae. It can hold its breath for up to 30 minutes, but again, it doesn’t breathe underwater—it simply stores air in its lungs.
Each of these species demonstrates that lizards can interact with aquatic environments effectively, even though they still rely on atmospheric oxygen.
Why Lizards Can’t Evolve Gills
Given that some lizards spend time in water, why haven’t any evolved gills like fish or amphibians?
There are a few evolutionary reasons:
−Lizards evolved on land, and their entire anatomy is optimized for air-breathing.
−Gills require a specific type of skin and circulatory system not present in reptiles.
−The energy cost and evolutionary shift required to grow functioning gills would be immense.
−Most aquatic behavior in lizards is intermittent—not enough to drive such a drastic evolutionary change.
Because of these factors, lizards have adapted in ways that support short-term survival in water rather than permanent aquatic life.
Can Lizards Drown?
Yes, lizards can drown. If a lizard is submerged too long and cannot reach the surface to breathe, it will suffocate. Even water-loving species have a limit to how long they can stay underwater. Drowning may happen more often in captivity, where artificial ponds or tanks don’t allow escape routes.
What Happens Physiologically When Submerged?
When submerged:
−The oxygen supply is cut off.
−The metabolic rate slows to conserve energy.
−Blood oxygen levels drop.
−If submerged too long, brain damage or death can occur due to oxygen deprivation.
For short durations, some lizards have adapted to minimize harm during these physiological changes. But there is always a limit.
Can Lizards Evolve to Breathe Underwater in the Future?
While evolution is unpredictable, it is unlikely that lizards will ever evolve to truly breathe underwater like fish. Their current biological framework is too specialized for land life. However, we may see more examples of adaptations like air bubbles, extended breath-holding, or even behavior changes that improve survival in aquatic settings.
What Does This Mean for Pet Owners?
If you keep a lizard as a pet:
−Do not submerge it intentionally.
−Provide shallow water for drinking or occasional soaking.
−Always ensure t
Understanding the limitations of your reptile’s respiratory system is essential to keeping it safe.
Conclusion: The Balance of Evolution and Environment
Lizards are not equipped to breathe underwater in the traditional sense. They do not have gills or any natural mechanism to extract oxygen from water. However, nature is full of surprises. Some lizards have evolved astonishing adaptations, such as breath-holding and bubble rebreathing, that allow them to survive temporary submersion.
These features demonstrate the incredible flexibility of life in response to environmental challenges. While no lizard can truly breathe underwater, their ability to endure aquatic environments—however briefly—is a testament to evolutionary creativity.
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