If you have ever confused slugs and snails, you are forgiven. The two share significant similarities that can create confusion. While slugs and snails belong to the class Gastropoda and the Phylum Mollusca, they still have several identifiable differences.
Snails and slugs are not the same thing. Slugs lack a shell, whereas snails are identifiable by their large, coiled shells on their backs. Although they inhabit similar habitats, slugs can squeeze into tree bark using their compact bodies, a feat that snails cannot accomplish.
Slugs and snails may share several similarities, but they are distinct animals. This article will elucidate the key differences between these two slow-moving creatures.
Major Similarities and Differences Between Snails and Slugs
| Snails | Slugs | |
| Feature | Snails have their characteristic, coiled shells. | Slugs do not have a shell but an identifiable muscular outer covering. |
| Size | Snails attain a smaller body size of up to 10 inches (25 cm), shorter than slugs. | Slugs can grow up to a maximum size of 15 inches (38 cm), longer than snails. |
| Lifespan | Snails have shorter life spans, with a maximum of three years in the wild. However, they can live up to 15 years in captivity. | Slugs can live for up to six years in the wild. |
| Activity | Snails are active during the day and night, spending most of their lifetime searching for food and sleeping when fully fed. | Slugs are nocturnal and primarily feed at night. |
| Movement | Snails move in a manner that resembles walking on hundreds of feet, achieved through muscular contractions that enable them to move faster than slugs. | Slugs seemingly drag their bodies while moving, resulting in their slow-moving nature. |
| Edibility | Snails are edible. | Slugs are also edible, though they are less preferred compared to snails. |
| Slime | Snails secrete slime from foot glands to aid in their movement. | Slugs also secrete slime from their foot glands, which helps them move. |
| Feeding | Snails have rasping mouths that allow them to feed on various plants. | Slugs have a similar mouth structure, making them the most dangerous farm pests. |
Snails: What Are They?
Classification
Snails primarily belong to the class of animals called gastropods, a term derived from the Greek words gastros and podos, meaning stomach and foot, respectively.
The name of the class suits snails well, considering their slow movement along surfaces as they consume plants. The acronym representing their stomach and foot describes their simultaneous eating and moving behaviors.
Case Study
A notable example, the brown garden snail Helix Aspersa, provides valuable insights into understanding snails in greater detail. While native to California, it gained popularity as a preferred delicacy in France during the 1850s.
Reproduction
Read: How Do Snails Reproduce?
Snails reproduce in various ways. While some snails reproduce asexually, some species are livebearers.
A few species of aquarium snails give birth to live young, allowing them to reproduce slightly faster than their egg-laying counterparts. One example of a common live-bearing snail is the Malaysian burrowing snail (Melanoides tuberculata).
Related Reading: Malaysian Trumpet (Burrowing) Snail Care for Beginners
During mating, the snail taking the male role can be identified as it will always be on top. In the reproductive process, two snails engage in courtship until they mutually agree to mate.
During mating, both snails simultaneously transfer sperm into each other’s bodies. Within three days of mating, the snails will lay eggs, although in some cases, this may occur up to six days after fertilization.
A snail’s eggs are typically pale white in color and have a small diameter, measuring about an eighth of an inch.
The snail seeks a suitable spot on soft soil to deposit the eggs in masses. Each mass can contain an average of 86 eggs, a strategy employed to maximize the chances of successful hatching.
Snails are well aware of the perils in the wild, and their strong parental instincts drive them to protect their offspring. They lay up to 400 eggs at once as part of this effort. Under normal circumstances, most snail eggs will hatch, and the young snails will emerge from their eggshells.
Immediately after hatching, they consume the eggshells, which serve as their initial source of calcium. This practice is vital as calcium is necessary for the growth and development of their protective shells.
The baby snails remain in the nest until their shells have strengthened sufficiently before venturing into the world.
Lifespan
In the wild, snails typically have a lifespan of up to three years. During this time, they dedicate themselves to searching for food or taking rest periods after satisfying meals.
Snails are active both during the cover of darkness, such as nighttime, as well as in foggy or cloudy conditions.
Behavior
When confronted with any sign of danger, snails instinctively retreat into the protective confines of their shells. They also retract into their shells during unfavorable weather conditions.
Once the threat has passed or the weather becomes more favorable, they emerge from their shells and resume their quest for food.
Slugs: What Are They?
Classification
Like their counterparts, slugs also belong to the gastropods class. Additionally, some slugs are classified under a sub-class called Pulmonata, which refers to their soft and slimy bodies.
Habitat
While slugs exist in various species, most of them inhabit the land. However, a unique species, Nudibranchia, derives its name from a Latin term meaning “naked gills.”
These slugs possess gills that allow them to breathe underwater, enabling their survival in aquatic environments. In contrast, other members of the slug family primarily reside on land.
Related Reading: Can Snails Live Underwater?
Food
Slugs are primarily herbivorous and can pose a significant threat to well-maintained gardens. These slow-moving creatures can cause severe damage to plants, often beyond recovery.
However, a few carnivorous species, such as Testacellidae, are found mainly in European countries. These carnivorous slugs do not feed on their own kind but readily consume their rivals, snails. In the absence of sufficient snail prey, they may resort to consuming earthworms.
Reproduction
Like snails, slugs are hermaphrodites, possessing male and female sex organs. However, their courtship rituals differ from those of snails.
The mating process begins with an intricate courtship, where slugs identify suitable mates through scent. The selection of a suitable mate is also influenced by individual courtship behavior and unique interlocking devices specific to each species.
Due to their various species, the courtship process among slugs is elaborate and often fascinating, ensuring mating occurs only within their own species. It would be intriguing to explore what would happen if slugs from different species were to mate.
Now, let us delve further into the similarities and differences between snails and slugs. One notable difference is the faster hatching of slug eggs.
Baby slugs also grow rapidly but do not need to feed on their eggshells. Unlike snails, slugs do not require significant amounts of calcium since they lack shells that would necessitate such a nutrient.
Furthermore, slug offspring tend to wait out the harsh winter and emerge from their nests at the first signs of spring. Their emergence can be a nightmare for humans as these young slugs devour plants and leaves with tongues lined with thousands of teeth.
Related Reading: Do Snails Have Teeth?
Summary
Until now, you might have considered a slug simply a snail with a missing home – the shell on its back. While there is some truth to that, it does not mean that snails and slugs are identical.
These two creatures are distinct animals with numerous similarities but notable differences. Snails possess a distinctive shell, whereas slugs lack one and will never acquire one.
Slugs will never transform into snails, and vice versa. Nonetheless, they are linked by their classifications and reproductive behaviors.
Sources
- Animalia: Testacella Scutulum
- AZ Animals: Snail Eggs: What They Look Like & 7 Fun Facts
- Pets on Mom.com: The Reproduction of Aquarium Snails
- Wonderopolis: How Are Slugs and Snails Different?
- AZ Animals: Sea Slug
- Orange County Mosquito and Vector Control District: Pest Control Bulletin No. 37: Snails and Slugs
- Britannica: Slug
- Discover Wildlife: How Do Slugs Mate?
- Oregon State University: Control Slugs Now as They Lay Eggs to Hatch in Spring
