Snails, often seen as small, slow-moving creatures, have a unique method of breathing that might be surprising to most people. Despite their tiny size, these creatures possess the ability to breathe air, though the specific process varies depending on the type of snail. The distinction in their breathing systems stems from the difference between land and aquatic snails.
Land snails, as well as some freshwater pond snails, have a simple breathing system that allows them to extract oxygen from the air through a small opening known as a pneumostome. When not in use, they can close the pneumostome to retain moisture, demonstrating a key difference from human respiration. On the other hand, certain aquatic snails possess gills to absorb oxygen from water, while some have evolved other adaptations such as snorkel tubes to breathe air from the surface. Pond snails exhibit an interesting ability to breathe through a rudimentary gill by flooding their pallial cavity when their habitat freezes over, allowing them to survive in harsh conditions.
Though snails might not seem like the most fascinating creatures, their adaptive breathing systems display a remarkable complexity for such small organisms. Understanding the different ways in which snails breathe offers valuable insights into their survival strategies in various environments.
Snails, both land and aquatic, have developed unique respiration methods to survive in their respective habitats. Their anatomy comprises essential organs and physiological adaptations for breathing. This section will discuss the pulmonary and cutaneous respiration of snails.
Land snails, or pulmonate snails, typically breathe using a lung called the pallial cavity. The pallial cavity is located within the snail’s mantle, a muscular protective layer that covers the internal organs and secretes the material that forms the shell (Missouri Department of Conservation). As snails moved from water to land, they evolved from using gills to this primitive lung, enabling them to breathe air.
In addition to pulmonary respiration, some snails also breathe through their skin or cutaneous respiration. Water snails, for example, can absorb oxygen through their skin. This ability, however, also means that they continually face water loss through their skin.
Aquatic snails that moved back to fresh water either re-evolved external gills or stayed close to the surface to gulp air occasionally using a snorkel tube. The gills are located in the pallial cavity and resemble a double comb with a stem.