When you look at an axolotl with those feathery external gills, it’s easy to assume they breathe like fish—gills only, no lungs involved. But axolotls hold a surprising secret that catches most people off guard. Understanding their complete respiratory system explains some of their unusual behaviors and helps you provide better care.

The Quick Answer

Yes, axolotls have fully functional lungs. Despite living underwater their entire lives and having prominent external gills, axolotls possess a pair of working lungs inside their body cavity. They occasionally swim to the surface to gulp air, filling these lungs with oxygen. This makes them bimodal breathers—using both gills and lungs simultaneously. The lungs serve as backup breathing organs and help with buoyancy control.

The Anatomy of Axolotl Lungs

What They Look Like

Axolotl lungs are surprisingly simple structures compared to mammalian lungs:

Two lung sacs sit on either side of the body cavity, running lengthwise through the torso. Each sac is roughly cylindrical and stretches from behind the head toward the back half of the body.

Thin, membranous walls make up the lung structure. Unlike the complex, spongy tissue of human lungs with millions of tiny air sacs, axolotl lungs are basically hollow bags with some internal folds.

Blood vessels line the walls where gas exchange happens. Oxygen from air passes through the thin membrane into blood vessels, while carbon dioxide moves out.

A simple opening (glottis) at the back of the throat connects the lungs to the outside. When an axolotl gulps air, it passes through the mouth, through the glottis, and directly into the lungs.

Size and Capacity

The lungs aren’t huge but they’re substantial:

• Each lung roughly equals 5-8% of the axolotl’s total body volume
• In an adult axolotl, lungs might be 2-3 inches long
• They can hold enough air to provide noticeable buoyancy
• Capacity varies by individual size and age

You can’t see the lungs from outside (they’re internal organs), but you can sometimes see the body expand slightly when an axolotl takes a big gulp of air.

Development Timeline

Lungs don’t appear immediately at hatching:

Week 1-2: Baby axolotls have no functional lungs. They rely entirely on gills and skin breathing.

Week 3-4: Lung tissue begins developing inside the body cavity. The structures form but aren’t used yet.

Week 5-6: Lungs become functional. Young axolotls start making occasional trips to the surface for air gulps.

Week 8+: Lungs are fully developed and integrated into the breathing system alongside gills.

By the time you buy a juvenile axolotl from a breeder (usually 3-4 inches long), the lungs are already working.

Why Axolotls Have Lungs

Evolutionary Background

The presence of lungs in an aquatic animal makes sense when you look at axolotl evolution:

Ancestral salamanders developed lungs to survive in oxygen-poor water or to transition between water and land. Many ancient amphibians lived in swampy, stagnant waters where gills alone couldn’t extract enough oxygen.

Neoteny preserved juvenile features including gills, but didn’t eliminate adult features like lungs. Axolotls essentially kept both childhood and adult respiratory organs.

No evolutionary pressure to lose lungs existed because they don’t cause problems and provide benefits. Unlike some fully aquatic animals that lost lungs over millions of years, axolotls retained theirs.

Related salamanders that metamorphose lose their gills but keep their lungs when they become terrestrial. Axolotls just keep both sets of equipment.

Practical Benefits

Having both gills and lungs provides real advantages:

Backup oxygen source saves lives when water quality drops. If gills can’t extract enough oxygen from poor water, lungs fill the gap.

Seasonal survival matters in their natural habitat. Lake Xochimilco experiences seasonal changes in water oxygen levels. Lungs help axolotls survive warm summer months when dissolved oxygen drops.

Buoyancy control is an unexpected benefit. Air in the lungs helps axolotls adjust their position in the water column without constantly swimming.

Energy efficiency comes from reducing swimming effort. A properly buoyant axolotl uses less energy maintaining position.

Stress tolerance improves because axolotls can survive brief periods of terrible water conditions that would kill gill-only breathers.

How Axolotls Use Their Lungs

The Surface Breathing Process

When an axolotl decides to use its lungs, here’s what happens:

Swimming upward begins when the axolotl pushes off the bottom with its legs. The movement is smooth and purposeful, not panicked.

Approaching the surface happens quickly. The axolotl angles its head upward and swims directly to the top.

Breaking the surface involves poking just the nose and mouth above water. The head tilts back slightly.

Opening the mouth creates a clear passage to the glottis. You’ll see the mouth open wide at the surface.

Gulping air happens in one quick motion. The throat expands as air rushes into the lungs. It looks like a fast gulp or swallow.

Immediate descent follows. The axolotl rarely lingers at the surface—gulp and go takes about 1-2 seconds total.

Exhaling old air sometimes happens before gulping fresh air. You might see bubbles release from the mouth.

How Often They Surface

Frequency varies dramatically based on conditions:

Perfect water (60-64°F, high oxygen):

• Once every 1-3 hours
• Sometimes even less frequently
• May skip surface trips for 6+ hours

Good water (65-68°F, moderate oxygen):

• Once every 30-60 minutes
• Regular but not concerning
• Normal behavior pattern

Acceptable water (68-70°F, lower oxygen):

• Once every 15-30 minutes
• More frequent than ideal
• Monitor conditions

Poor water (70-72°F, low oxygen):

• Once every 5-15 minutes
• Red flag situation
• Immediate intervention needed

Critical conditions (72°F+, very low oxygen):

• Constantly at surface
• Near-continuous gulping
• Emergency situation

Normal vs. Problem Behavior

Normal lung use looks like:

• Calm, controlled swim to surface
• Quick gulp and immediate descent
• No gasping or distress signals
• Occurs occasionally throughout day
• Axolotl appears relaxed

Problem lung use looks like:

• Frantic swimming to surface
• Gasping with mouth wide open
• Staying at surface for extended periods
• Happening every few minutes
• Axolotl appears stressed or exhausted

Lungs vs. Gills: What’s the Difference?

Gill Breathing (Primary Method)

Axolotl gills are the main oxygen source under normal conditions:

Advantages of gills:

• Constantly active (no need to surface)
• Highly efficient in oxygen-rich water
• Extract oxygen directly from surrounding water
• Don’t require any special behavior
• Work 24/7 without conscious effort

Limitations of gills:

• Only work in water
• Efficiency drops when oxygen is low
• Can be damaged by poor water quality
• Require clean water to function properly

Lung Breathing (Backup Method)

Lungs provide supplemental oxygen when needed:

Advantages of lungs:

• Access atmospheric oxygen (21% O2 vs. <1% dissolved in water)
• Work even when water oxygen is zero
• Provide buoyancy control
• Function independently of water quality

Limitations of lungs:

• Require surface access
• Less efficient than mammal lungs
• Need conscious action (swimming up)
• Can’t be used continuously without exhaustion

Why Both Matter

The combination creates a resilient system:

In ideal conditions, gills do 80-90% of the work, lungs contribute 5-10%, and skin breathing adds another 5-10%. This balanced approach uses the most efficient method (gills) while keeping backup systems (lungs and skin) ready.

When conditions deteriorate, the balance shifts. Lungs might jump to 30-40% of oxygen intake, helping the axolotl survive situations that would kill a fish.

Buoyancy Control with Lungs

How It Works

Axolotls use their lungs almost like a built-in flotation device:

Air in lungs reduces density. A belly full of air makes the axolotl lighter relative to the water around it.

Adjusting air volume changes buoyancy. Taking in more air makes them float higher. Releasing air lets them sink.

Neutral buoyancy saves energy. By matching their density to the water, axolotls can hover in place without swimming effort.

Position control improves. Proper buoyancy helps them maintain preferred depth and position.

Observable Behaviors

You’ll notice buoyancy-related lung use:

Floating higher than normal after a surface trip indicates the axolotl took a big gulp of air. This is intentional when they want to rest in mid-water.

Releasing bubbles from the mouth shows the axolotl expelling excess air to descend. This happens when they want to sink back to the bottom.

Struggling to stay down means too much air in lungs. The axolotl might grab decorations or wedge under objects to stay submerged.

Sitting heavily on bottom indicates empty lungs. The axolotl is deliberately staying negatively buoyant.

Some axolotls seem to enjoy floating around mid-tank with air-filled lungs, while others prefer staying grounded on the bottom. Both are normal preferences.

Do Lungs Mean They Can Live on Land?

The Short Answer: No

Despite having functional lungs, axolotls cannot survive long-term out of water:

Gills dry out in minutes. The delicate gill filaments stick together when dry, stopping gill breathing completely. This happens within 5-10 minutes.

Skin must stay moist. Axolotls rely on skin breathing for 10-30% of their oxygen. Dry skin can’t absorb oxygen and becomes damaged.

Lungs alone aren’t sufficient. Axolotl lungs are too simple and inefficient to meet 100% of oxygen needs without help from gills and skin.

Body overheats quickly. Without water cooling, body temperature rises rapidly. Axolotls can’t regulate temperature on land.

Dehydration happens fast. The permeable skin loses water rapidly in air. Critical dehydration occurs within 30-60 minutes.

Emergency Situations

If an axolotl jumps out of the tank:

First 5 minutes: Salvageable with quick action. Gently return to cool water immediately.

5-10 minutes: Serious but potentially recoverable. Expect gill damage and stress.

10-15 minutes: Critical situation. May survive but with lasting damage.

15+ minutes: Usually fatal. Even if revived, long-term survival is unlikely.

Speed is everything. The faster you return them to water, the better their chances.

Comparing to Other Amphibians

Salamanders That Metamorphose

Most salamanders start aquatic with gills, then metamorphose:

Larval stage: Gills and developing lungs (like axolotls)

Metamorphosis: Lose gills, develop stronger lungs, become terrestrial

Adult stage: Lungs only (some also use skin breathing)

Axolotls essentially never finish this process. They sexually mature and reproduce while still in the larval form with both gills and lungs.

Frogs and Toads

Frogs follow a different pattern:

Tadpole stage: Internal gills only, no lungs

Metamorphosis: Develop lungs, lose gills completely

Adult stage: Lungs and skin breathing only

Axolotls are unique in keeping external gills alongside lungs indefinitely.

Fully Aquatic Salamanders

A few salamander species have lost lungs entirely:

Lungless salamanders (Plethodontidae family): Breathe only through skin and mouth lining

Advantages: More streamlined body, better for fast-moving streams

Disadvantages: Require extremely high water oxygen, can’t survive poor conditions

Axolotls’ lung retention gives them greater environmental flexibility than these specialized species.

Caring for Lungs and Gills Together

Water Temperature

Temperature affects both breathing systems:

60-64°F (ideal):

• High dissolved oxygen for gills
• Minimal lung use needed
• Both systems work efficiently

65-70°F (acceptable):

• Reduced oxygen for gills
• More frequent lung use
• Both systems working harder

70-75°F (stressful):

• Very low oxygen for gills
• Heavy reliance on lungs
• Risk of exhaustion

75°F+ (dangerous):

• Insufficient oxygen for gills
• Constant lung use can’t compensate
• Life-threatening situation

Surface Access

Never block surface access:

Floating decorations that cover the entire surface prevent air breathing. Always leave open space.

Tight lids should have gaps or be removable. Axolotls need to break the surface.

Water level should be 2-3 inches below the tank rim to prevent jumping while allowing easy surface breathing.

Plant coverage is fine as long as open areas exist. Axolotls will find the gaps.

Water Flow

Circulation affects both breathing methods:

Gentle flow is ideal. It brings fresh oxygen to gills without creating current that damages delicate gill filaments.

Air stones help by increasing dissolved oxygen, reducing lung use frequency.

Too-strong filters damage gills, forcing more reliance on lungs and potentially exhausting the axolotl.

Signs of Lung Problems

Overinflation

Sometimes axolotls gulp too much air:

Symptoms:

• Floating uncontrollably at surface
• Unable to dive even when trying
• Tumbling or rolling in water
• Distressed behavior

Causes:

• Gulping air repeatedly in panic
• Swallowing air while eating
• Respiratory infection affecting air release

Treatment:

• Usually resolves naturally as air is absorbed or burped out
• Provide hides near surface so they can rest while floating
• If persistent over 24 hours, consult a vet

Inability to Use Lungs

Rarely, lung function becomes impaired:

Symptoms:

• Never surfacing even in poor conditions
• Staying at surface gasping without gulping
• Abnormal body position or balance

Causes:

• Physical injury to glottis or lungs
• Infection blocking air passages
• Neurological problems

Treatment:

• Ensure perfect water quality
• May need antibiotics for infection
• Severe cases require exotic vet consultation

Frequently Asked Questions

Can you see axolotl lungs from the outside?
No, lungs are internal organs. You can’t see them, but you might notice the body expand slightly during a big air gulp.

Do axolotls breathe air in their sleep?
Yes, they surface for air even while resting or sleeping. The process is automatic and doesn’t wake them fully.

What happens if an axolotl can’t reach the surface?
In good water conditions, they can survive on gills and skin breathing alone. In poor conditions, they may suffocate without lung access.

Do baby axolotls have lungs?
Not immediately. Lungs develop around 3-4 weeks after hatching and become functional by 5-6 weeks.

Can axolotls survive with damaged lungs?
Yes, gills can handle 80-90% of oxygen needs in good conditions. Damaged lungs are survivable if water quality stays perfect.

Why does my axolotl gulp air so often?
Frequent surface breathing usually indicates low dissolved oxygen from warm water or poor quality. Test your water parameters.

Do axolotls prefer gills or lungs?
They prefer gills in good conditions because it requires no effort. Lungs are used only when needed or for buoyancy adjustment.

Can axolotls cough or choke?
They can expel water or bubbles forcefully if something blocks their throat, which looks like coughing. True choking is rare but possible with large food.

How long can axolotls hold their breath?
This question doesn’t quite apply since they’re primarily water breathers. They can go hours between air gulps in good conditions, but they’re not “holding breath” like we think of it.