Do Aquarium Snails Have Gills?

Do Aquarium Snails Have Gills?

Many people ask how aquarium snails breathe in the water, do they have gills? In this article, we have explained the respiratory organs and the breathing mechanism of snails.

Do Aquarium Snails Have Gills? Yes, aquarium snails have comb-shaped gills to perform respiratory functions. Their respiration process consists of oxygen-absorbing blood in their body and releasing carbon dioxide into the water. However, a few exceptions evolved lungs along the gills to improve their respiration and increase their territorial range. Some land snails living in water develop siphon like organs to take O2 from the air without exposing themselves out of the tank. 

Do Aquarium Snails Have Gills?

Aquarium snails belong to the group of freshwater organisms commonly found there as tank cleaning agents.

Like every living thing, they need sufficient O2 to maintain their life cycle. Snails have different respiratory organs depending on their habitat and as a result of evolution. 

One of the simple respiration processes occurs through the skin of a snail. The second mechanism for snails is to breathe through their gills present in the pallial cavity. Third and evolved respiratory part of their body is the lungs.

It present in land snails. Gills in snails do not provide sufficient O2 in times of high metabolic rate. However, they develop a specific tubular organ like a siphon to filter O2 from the air above the water level without coming to the surface. 

Respiratory organs in snails

The various breathing organs in aquarium snails develop due to evolutionary processes to cater to different environmental changes.

Some of them contain a single respiratory organ, while others have all of them to support their breathing process. Those organs are their skin, gills, lungs, and siphon shaped snorkel tube for outer breathing.

Skin Surface

The skin surface of aquatic snails is thin and permits water to pass through it. A part of their O2 requirement fulfills through the skin.

However, it is not capable of fulfilling the complete respiration process of their body. Therefore, other organs like gills and lungs are present to facilitate the breathing process.


The ancient species of snails were aquatic and a pair of gills. With time, it reduced to one gill due to less space inside their shell to manage other organs developed as a part of the evolutionary process.

They are in the shape of a double comb with a stem. The stem has small filament extensions like comb teeth or feathers on both sides. It is present inside the mantle cavity.

Some of them also lose one side of feathery projection and top of the pallial cavity. So they have a gill in the shape of a single comb with a stem. These extensions or filaments increase the surface area for gas exchange.

A type of aquarium snail known as nudibranchs has open gills outside their shell visible in the water. The reason is a reduction in shell size along with the gill and mantle cavity.


Snails residing on land have developed lungs from their gills to accommodate in their new environment. Gill in these snails reduce, and a capillaries network form on the wall of the pallial cavity.

The exchange of gases like O2 enters the blood and carbon dioxide leaves through the wall of capillary vessels.

The floor of the pallial chamber acts as a diaphragm to complete the breathing process. A small muscle in the shape of a ring prevents water loss through the opening of the cavity. 

Some species of land snails returned towards the water and developed external gills to perform their respiratory function. Many aquarium snails can live out of water.

A siphon or Snorkel Tube

It becomes a flexible tubular structure extend on the left side of the neck over the snail’s head. It helps the aquarium snails to breathe air while staying underwater. Its muscles contract, and it becomes like a snorkel or a pipe to fill their lungs with air.

The length tube varies depending upon the snail’s species ranging from very long (3 times their body length) to shorter (lesser than their size).

It is beneficial for snails that remain submerged in water during the breathing process and fulfill O2 requirements in high metabolism with gills coordination.

Snails Breathing Mechanism

Snails’ respiration is similar to other living organisms. It involves the two gases exchange, like O2 and carbon dioxide, to the blood and the surrounding. O2 diffuses into the blood while CO2 leaves the body into the air. 

Lungs and gills provide surface area to assist this process for happening. Gills have a filament-like structure for breathing. Lungs are like air sacs with small capillaries to exchange gases between blood and air.

The muscular ring closes to protect the lungs from water while the snail submerges into the aquarium tank.

The respiration process completes about 10 to 20 contractions of the respiratory organs with one movement per second.

Aquarium Settings to Assist Breathing of Snails

Aquarists should make various arrangements to facilitate the respiration of the snails present in the aquarium.

We will give simple tips for tank arrangements according to their species and breathing organ. You take care of the following points that help them out.

 Snails with snorkels around a space of 2-3 inches above the water level in the tank should keep empty. It helps them to siphon air into their lungs.

The water in their cavity to continuously refresh improve respiration. Small hair-like structures on their skin perform this job. It maintains the moisture level of the gills.

For species having gills only for respiration, water should be richly oxygenated. Otherwise, your pet can suffer due to less O2.

Bimodal species (having both lungs and gills) have efficient respiration. However, they mainly rely on the lungs for breathing. Therefore, compatible settings should make to facilitate them.

Use air stones in the aquarium to avoid loss of O2.

Keep the harmful gases like ammonia and nitrite levels low in the tank.

Use plantation in the tank to maintain O2 levels.

Keep the tank covered as birds can damage the snails coming towards the surface for breathing.

Choose appropriate aquatic species of snails for your aquarium having feasible respiratory organs ( both lungs and gills but preferably gills).

Effect of Water Quality on Aquarium Snail’s Gills

Aquarium snails are sensitive organisms to the quality of water in the tank. They require a smooth water flow through their mantle cavity to improve the efficiency of their breathing process. Therefore, the purity of water is essential to avoid suffocation or less oxygenation of their blood. 

Harmful levels of fungus, parasites, and other pollutants in water due to waste food will restrict themselves inside their shells. It will suffer their respiration and cause them to suffocate. Some snails flip over and try to move to a side.

The presence of ammonia, carbon dioxide, and carbon monoxide in the aquarium will hinder the gas oxygen process and hence less O2 in the blood. 

Due to the above reasons, it is mandatory to maintain water quality parameters as per recommended settings.

Disease Affecting Snail’s Gills

Different snail diseases affect their lungs and gills. We will discuss a few of them.

Edema: Its cause is excessive fluid in the tissues, and their body becomes swollen. Due to the swelling, the mantle cavity fills with these tissues. It also blocks the air and water pathways and therefore disables the function of gills and lungs. It usually occurs at an older age.

Physical Damage: 

Other predator’s presence in the tank or any physical activity can cause damage to the snail’s respiratory organs. 

They are more vulnerable if they have open gills outside their shell or snorkel tube to suck air outside the water surface. 

A siphon or snorkel tube is a large tube. It can be tempting for some predators to bite and damage it.

Types of aquarium snails with gills

All species of aquatic snails have gills as primitive breathing organs. However, some species have evolved lungs to make their respiration efficient.

Therefore, those species have both lungs and gills. Those with lungs are called palmonite. One of the examples of such species is the Apple snail with all three types of respiratory organs.

Nerite snails breathe through absorbing while mystery snails have gills and a siphon tube for their respiration.


We have discussed the gills in Snails, their functions, their evolution to lungs, other related organs, and their diseases. Most of the aquarium snails have gills with other evolved organs like lungs and siphon tubes.

We have also discussed some suitable instructions for aquarists to make arrangements for easy breathing of snails and improve the water quality in the tank that is also crucial for other pets in the tank.

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