The question of whether snails consume slugs is often posed by gardeners and naturalists alike, as both mollusks are common sights in yards and wild spaces. The answer depends entirely on the specific species of snail under consideration. While the vast majority of terrestrial snails are herbivores or scavengers, a small but notable group of predatory snails has evolved unique adaptations to hunt and consume other mollusks, including slugs and other snails.
Most Snails Are Herbivores
Most terrestrial snails, including the typical garden snail, maintain a primarily herbivorous or detritivorous diet. These common species primarily feed on decaying organic matter, such as dead leaves and plant debris, acting as nature’s recyclers. They also consume algae, fungi, and tender new plant growth, which often makes them unwelcome visitors in cultivated gardens.
A snail’s mouth contains a specialized organ called the radula, which functions like a rough, flexible tongue covered in thousands of microscopic teeth. The herbivorous snail uses this rasping structure to scrape food particles from surfaces, such as chewing through a soft leaf or rasping algae off a rock. Their focus is generally on stationary food sources that do not require active pursuit.
Identifying Carnivorous Snail Species
The few species that do hunt slugs are remarkable exceptions to the herbivorous norm, having evolved into specialized predators. One of the most well-known is the Rosy Wolf Snail (Euglandina rosea), a species native to the Southern United States. This predator, sometimes called the “cannibal snail,” feeds almost exclusively on other snails and slugs throughout its life cycle.
The genus Powelliphanta, found in New Zealand, represents another group of large, carnivorous snails that prey on earthworms and slugs. Similarly, the Gray-footed Lancetooth (Haplotrema concavum) in North America also hunts and consumes other snails and slugs. These predators have adapted to a protein-rich diet, making them molluscivores.
These specialized hunters have been deliberately introduced in some areas, such as the Rosy Wolf Snail in Hawaii, in misguided attempts to control invasive agricultural pests like the Giant African Land Snail. Unfortunately, the introduced predators often prefer to consume smaller, native species, sometimes driving them to extinction. Their predatory behavior extends to any suitable mollusk prey, not just slugs.
The Mechanics of Mollusk Predation
The hunting technique of a carnivorous snail is a display of biological specialization. Rosy Wolf Snails, for example, use specialized chemical receptors located on their oral lappets (sensory appendages) to track the slime trails left by their prey. They move up to four times faster than the average garden snail, allowing them to easily overtake their slower targets.
Once the prey is located, the predatory snail’s radula is deployed differently than in its herbivorous relatives. In the Rosy Wolf Snail, the radula teeth are adapted into elongated cones, and the snail often uses an eversible esophagus to consume its victims. If the prey is a small snail, the predator may ingest it whole, shell and all, utilizing the shell’s calcium for its own shell development.
For a larger slug or snail, the predator will insert its muscular pharynx into the shell’s opening, using its adapted radula to mince and suck out the soft body tissues. The New Zealand Powelliphanta snails also use their radula to scrape chunks of flesh from their prey, often earthworms or slugs, prolonging the feeding process. These unique anatomical and behavioral traits distinguish the few carnivorous snails from the vast majority of their herbivorous kin.