You’re probably already aware but there are different types of snail — sea snails, freshwater snails, and land snails. Sea snails and freshwater snails, as the name suggests, both live in water either all or most of the time, and they can breathe underwater.
Land snails, on the other hand, live on land. But that’s not to say that they can’t spend time (and breathe) in water, though.
The snail world is quite a complex one, especially when it comes to anatomy, but let’s simplify the breathing process of gastropods a little bit, shall we?
Does a Snail Need Air?
Yes, a snail needs air and will breathe oxygen in much the same way that pretty much every single other animal on the planet needs air. Even water-dwelling snails need air, just as a fish needs air. They don’t breathe in quite the same way, but they do still breathe air all the same.
Can Snails Breathe Underwater?
Yes, some snails can breathe underwater and even float — and they aren’t just confined to sea or freshwater snail species, either.
Not all species of snail can breath underwater, though.
Snails will drown if they are unable to breathe in oxygen.
Different species will have different approaches to being able to take in oxygen underwater, and it’s all said to be down to the way they evolved. Some snail species have gills, but others have lungs. A few gastropods have two gills, others have one. Some even have both sets of breathing apparatus – gills and a lung! (Talk about greedy!)
And if things weren’t already complicated enough, some snails even breathe underwater using a snorkel-like appendage.
Did you manage to keep up with all of that?
It’s believed that all snails were once creatures that lived in water, with land snails coming later as evolution did its thing. It is because of this evolutionary process that the snail’s respiratory system is so complex and varied. Two gills evolved into one gill, which then evolved into a lung and/or lung-plus-gill. But some of the snails kept their original ‘features’…
Super confusing, right? It’s just another example of how complex evolution really is.
How Do Snails Breathe Underwater?
As previously mentioned, different snails breathe in different ways. It’s quite the complex little world.
Most sea snails either have one or two gills, using them in much the same way a fish uses a gill to breathe. That rule doesn’t apply to all salt water gastropods, though. Some of them have a lung, just like humans do.
Pulmonates, also known as Pulmonata, are the owners of such a pallial lung, which is a group that includes sea snails, freshwater snails, and land snails.
Also known as Prosobranchia, gills absorb oxygen that has been dissolved in the water. These snails essentially breathe like a fish.
Most marine snails fall into the gilled snails category. Other gilled species include freshwater nerite snails and mud snails.
Pulmonata snails, also known as lunged snails, have a lung, as the nickname suggests. Air is drawn into the body, into the lung-like organ, where oxygen is then absorbed. Some snails draw water in and then absorb the dissolved oxygen from it.
Lunged species include bladder snails, pond snails, and ramshorn snails. Most land snails are lunged snails.
Lunged snails breathe like little scuba divers, by essentially taking a small oxygen tank down with it. They head to the surface, collect a little bubble of air in a special capsule under the shell, and then head back down underwater until the bubble runs out. At that point, they return to the surface and start the process again.
In some snails with almost transparent shells, you can sometimes see the little bubble of air.
Lunged and Gilled Snails
Apple snails, also known by the scientific name Ampulliidae, have both the lung-like organ and a single gill. The snails breathe underwater and on land with ease. This is referred to as branchial respiration.
Mystery Snails and Direct Pulmonary Respiration
Mystery snails breathe in a very unique way, much unlike other snail species. The aquatic snail is able to breathe air using a siphon that is positioned close to the head, and still live underwater.
These snails have gills and lungs, but they need to head to the water’s surface to breathe in air through the siphon. Because of this, if you have the species of snails in your tank, you must allow a few inches at the top, between the water and the lid, for snail breathing space.