Snail vs Slug: Difference and Comparison

Snails, as well as slugs, are gastropods that belong to the mollusc family that also comprises oysters, octopus, squid, mussels, and calamari. Snails and slugs come in a variety of colors, and there are over 60,000 different species.

Slugs and snails both like new, fragile growing plants and flourish in moist soil or plant waste. They feed on both existing and decaying plant matter.

Key Takeaways

1. Snails possess a hard external shell for protection, while slugs lack such a shell.
2. Both snails and slugs belong to the gastropod class, but slugs have evolved to survive without shells.
3. Snails and slugs share similar diets, consuming plants, fungi, and decaying organic matter.

Snail vs Slug

The difference between snail and slug is that the former organism comprises an exterior shell, whereas slugs don’t have a dedicated exterior shell. Snail refers to practically all gastropod molluscs with coiled shells in their adult state. Slug is a generic term for any gastropod mollusc which lacks a shell, does have a shell that is severely reduced, or even has a small internal shell.

A snail is just a shelled gastropod. Land snails, also known as terrestrial pulmonate gastropod molluscs, are commonly given this name.

The term “snail” is applied to many other representatives of the molluscan class Gastropoda, which has a coiled shell big enough for an animal to retreat entirely into.

Any ostensibly shell-less tropical gastropod mollusc is known as a slug or land slug.

Slug is, however, a frequent name for any gastropod mollusc with no shell, a rather small internal shell, or even no shell whatsoever, such as sea slugs as well as semi-slugs. 

Comparison Table

Parameters of Comparison	Snail	Slug
Anatomy	Snail has a shell covering to protect it from other organisms and predators at times.	On the other hand, Slug has no shell covering or a very small shell covering.
Speed	The ordinary snail can hit one millimeter every second. They are quicker than most of the slugs.	Slugs are slower when it comes to pace in terms of Snails.
Habitat	Snails swiftly conceal in their shells. Some snails have the ability to retract and seal their shells in order to provide additional protection.	Due to the fact that slugs do not have a shell on their back, they are able to effortlessly, if slowly, navigate into the tiniest of spaces, and they can even shrink themselves. They reap the benefits of wood panels, stone slabs, and scattered twigs.
Color	Snails are grey-colored with greyish or black shells.	Slugs can either be black or grey or yellow in color.
Life Expectancy	Snails live for almost 2-3 years.	On the other hand, Slugs can live up to 6 years or even more.

What is Snail?

In a general way, a snail is just a shelled gastropod. Land snails, also known as terrestrial pulmonate gastropod molluscs, are commonly given this name.

The term “snail” is applied to many other representatives of the molluscan class Gastropoda, which has a coiled shell big enough for an animal to retreat entirely into.

When the term “snail” is being used in a broad meaning, it refers not only to land snails but also to a variety of sea as well as aquatic snail species.

Snails are important to humans in a variety of ways, including as food, parasites, as well as pathogenic organisms, and their shells are used as aesthetic things and in jewellery.

The snail has cultural importance as well, as it is connected with laziness. A snail is also being used as an analogy: “slow as a snail” refers to those who are not progressing quickly enough.

The snail has a comparable shape to the Cochlea.

What is Slug?

Any ostensibly shell-less tropical gastropod mollusc is known as a slug or land slug. Slug is, however, a frequent name for any gastropod mollusc with no shell, a rather small internal shell, or even no shell whatsoever, such as sea slugs as well as semi-slugs. 

Land slugs are classified into multiple taxonomic groups, each of which belongs to a different historical branch that also includes snails. Despite obvious similarities in body shape structure, the different slug groups aren’t closely related.

The absence of a shell has occurred multiple times in evolutionary history, making the term “slug” polyphyletic.

Slugs’ bodies are primarily comprised of water. Therefore their sensitive tissues are susceptible to dryness since they lack a full-sized shell.

To thrive, they must produce defensive mucus. Due to the extremely damp ground, several species are quite active right after rain.

To help keep body fluids in arid situations, they lurk in damp locations such as under tree bark, broken logs, boulders, and man-made constructions such as planters.

During maturation, they, just like all the other gastropods, go through torsion (a 180° bending of the inner organs). Slug anatomy reveals the consequences of these rotations on the inside, yet the bodies of slugs seem to be more or less equal on the outside.

Main Differences Between Snail and Slug

1. Snail has a shell covering to protect it from other organisms and predators at times. On the other hand, Slug has no shell covering or a very small shell covering.
2. The ordinary snail can hit one millimetre every second. They are quicker than most of the slugs. Slugs are slower when it comes to pace in terms of Snails.
3. Snails swiftly conceal in their shells. Some snails have the ability to retract and seal their shells in order to provide additional protection. Due to the fact that slugs do not have a shell on their back, they are able to effortlessly, if slowly, navigate into the tiniest of spaces, and they can even shrink themselves. They reap the benefits of wood panels, stone slabs, and scattered twigs.
4. Snails are grey-colored with greyish or black shells, whereas Slugs can either be black or grey or yellow in color.
5. Snails live for almost 2-3 years. On the other hand, Slugs can live up to 6 years or even more.

References

1. https://www.sciencedirect.com/science/article/abs/pii/S0090825804010583
2. https://www.pnas.org/content/99/26/16841.short