Are snails insects? Debunking common misconceptions

Have you ever wondered if snails are insects? You’re not alone in pondering this question. To clarify, snails and slugs are actually mollusks, not insects. They are related to creatures such as conch, oysters, clams, and scallops [^1^]. Let’s explore some of the differences between snails and insects.

Snails belong to a diverse group of mollusks called gastropods, which have muscular feet for movement and breathe through either lungs or gills[^2^]. In contrast, insects have six legs and a three-part body consisting of a head, thorax, and abdomen. Another key difference is that snails have a single, spiral-coiled shell, while insects do not possess shells[^2^].

Some snails and slugs feed on fungi, decomposing plants, and soil, while others consume healthy plants, which can make them pests in your garden[^1^]. Meanwhile, insects have a wide range of feeding habits, such as herbivory, predation, and parasitism. So even though snails might share some similarities with insects in terms of diet, it’s important to remember that their classification and biology are fundamentally different.

Are Snails Insects?

Snails are not classified as insects. While both insects and snails belong to the larger group called invertebrates, they are placed in different categories. Let’s dig deeper into their differences.

Insects are part of the phylum Arthropoda, whereas snails belong to the phylum Mollusca, making them relatives of conch, oysters, clams, and scallops. One key difference between insects and snails is that insects have three main body parts: head, thorax, and abdomen, along with six legs. Snails, on the other hand, have a head, a muscular foot for movement, and a shell (external for snails and internal for slugs).

Below is a comparison table that highlights their differences:

Feature Insects Snails
Phylum Arthropoda Mollusca
Body Parts Head, Thorax, Abdomen Head, Foot, Shell
Legs Six None
Shell No Yes (Internal or external)

In conclusion, snails are not insects. Even though they share some similarities like being invertebrates and sharing some feeding habits, their body structure and classification put them in distinct categories.

Classification of Snails

Mollusk Characteristics

Snails belong to the phylum Mollusca which is characterized by having soft bodies and a muscular foot for movement. These soft-bodied invertebrates often have a hard protective shell. Some examples of mollusks include snails, slugs, oysters, and clams. A key feature of mollusks is their ability to breathe through either lungs or gills, depending on the species.

Types of Snails

Snails are classified under the class Gastropoda, which is the largest group of mollusks, with about 40,000 known species. These gastropods can be found in a variety of habitats such as land, freshwater, and marine environments. Some popular types of snails include:

  • Land Snails: Majority of snail species live on land and breathe through lungs. Examples include the Giant African Land Snail and the Roman Snail.
  • Sea Snails: These snails are found in marine environments and have gills to breathe. Examples include sea slugs and marine snails.
  • Freshwater Snails: These snails are found in aquatic environments like rivers and lakes and have either lungs or gills. The American Fisheries Society provides a list of freshwater snails found in Canada and the United States.

Comparison table of snail types:

Type Habitat Breathing Organ Examples
Land Snails Terrestrial Lungs Giant African Land Snail, Roman Snail
Sea Snails Marine Gills Sea slugs, marine snails
Freshwater Snails Aquatic Lungs or Gills Apple Snails

Study of Gastropods

The study of snails and other gastropods falls under the realm of biology, specifically within the class Gastropoda. Researchers and scientists examine the taxonomy, morphology, ecology, and behavior of snails to better understand their habitats, roles in ecosystems, and unique adaptations. By studying gastropods, you can gain insights into their evolution, environmental interactions, and even their potential uses in medical applications.

Distinctive Features of Snails

Hermaphroditic Nature

Snails are fascinating creatures, primarily because they are hermaphroditic. This means that they possess both male and female reproductive organs. This unique feature allows them to mate with any other adult snail of the same species, increasing their chances of reproduction.

Role of the Shell

Unlike slugs, snails have a hard, protective shell made of calcium carbonate. This shell serves as a crucial defense mechanism against predators and unfavorable environmental conditions. The size and shape of the shell vary among different snail species, but they all offer a secure shelter for their soft bodies.

Unique Snail Anatomy

Snails have some distinctive body parts that set them apart from other creatures. They have tentacles on their heads, which they use for sensing their surroundings and finding food. Another essential component in their mouth is the radula, a toothed organ that helps them scrape food into small particles. In addition, they have a muscular foot that allows them to move by using a wave-like motion.

Comparison Table

Feature Snail Insects
Body Sections Head, foot, shell Head, thorax, abdomen
Legs Absent 6 legs (usually)
Reproduction Hermaphroditic Separate sexes
Protective Shell Present Absent
Radula Present Absent

Reproduction

The reproductive process of snails is rather fascinating as it involves both eggs and larval stages. After mating, each snail lays eggs in a damp, secure location, ensuring a good environment for the young ones to develop. Snails begin their life cycle as larvae, and as they grow, they gradually transition into the adult stage. This development includes acquiring their signature shell and other essential features for a fully functional snail.

In conclusion, snails are unique creatures with numerous distinctive features that set them apart from insects. Their hermaphroditic nature, protective shell, specialized anatomy, and life cycle stages all contribute to their remarkable abilities and fascinating biology.

Snails in their Natural Habitat

Snail Habitats

Snails can be found in various environments, from land to sea. In forests, you may come across land snails taking shelter under fallen leaves or residing on tree trunks, feasting on plants and lichen. Sea snails, on the other hand, inhabit oceanic habitats, while some species can even thrive in deserts.

Invasive Snails

There are instances where snails can become invasive species, such as the garden snail. Invasive snails often compete with native species for resources and may cause harm to the local ecosystem. Implementing effective control measures is essential for maintaining the ecological balance.

Snails and their Diets

Snails have diverse diets, with some being herbivorous and others omnivorous. Their primary diet consists of:

  • Plants
  • Fruits
  • Vegetables
  • Lichen

Some snail species will also consume carrion, providing them additional protein and calcium as part of their diet.

Snails’ Role in Ecosystem

Snails play a vital role in their habitats, as they contribute to the cycling of nutrients within the ecosystem. They help break down organic matter, clearing up fallen leaves and other detritus that accumulates in their environments. In addition, some predatory snails, like the rosy wolf snail, feed on other, often invasive, snails, and slugs, which helps maintain the ecological balance.

In summary, snails inhabit various ecosystems, from forests to oceans, and are essential for maintaining balance within these environments. They have diverse diets, contributing to the cycling of nutrients in their habitats. It’s crucial to be aware of invasive snails and take appropriate measures to mitigate their impact on native species.

Reader Emails

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.

Letter 1 – West Indian Fuzzy Chiton from Puerto Rico

 

Hard shell purple bug at the coast of Puerto Rico
Thu, Feb 26, 2009 at 7:12 PM
I was staying at a hotel on the east coast of the island of Puerto Rico and went to the shore to look at the ocean at around midday. This thing was purple, had a hard shell, did not move at all, about 5 inches long and 3 inches wide. It was withing the rocks. This was in summer 2006.
Melyssa
East coast of Puerto Rico

Chiton
Chiton

Dear Melyssa,
The creature in your photograph is a Chiton. Chitons are primitive marine molluscs that have shells composed of 8 plates. The shells provide protection against waves which enable Chitons to survive on stormy rocky coasts. Chitons are sometimes called Sea Cradles.

Comment:
Sat, Feb 28, 2009 at 5:58 AM
Hi Daniel, Ah, another mollusk! This is Acanthopleura granulata (Gmelin, 1791), the West Indian fuzzy chiton. The shell plates of this chiton are actually brownish and are usually very eroded. The pink/purple color on this one is due to a layer of encrusting calcareous red algae. For more info see the Wikipedia article (which I put together.) Best wishes to you,
Susan J. Hewitt

Comment Update:
Sun, Mar 1, 2009 at 4:43 AM
I wanted to add:
1. That these chitons do move around, but only at night, grazing on microscopic algae which grows on the rock surface. Each one returns to its same spot on the rock at the end of the night.
2. That the maximum size of this species is about 3 inches in length.
3. There is a really excellent book on the chitons of P.R. called “Los Quitones de Puerto Rico” by Cedar I. Garcia Rios.
Susan Hewitt

Letter 2 – Two Land Snails from Florida

 

Subject: Florida land snails
Location: Florida
January 25, 2014 2:35 pm
My sister was given two land snails to care for. She said that they were collected in Florida. That’s all I know. I want to be sure these are not pest species, and secondly, if she decides to care for them I need to know what they might eat. Thanks.
Signature: Bruce

Snail From Florida
Snail From Florida

Hi Bruce,
We can post this request this morning, but we haven’t the time to research it right now, but we will try to identify your Snails later.  We have to confess that we don’t know much about Molluscs, but we do have a reader, Susan J. Hewitt, who frequently identifies Snails for us.  Perhaps she will read the posting and provide a comment.

Snail From Florida
Snail From Florida
Another Snail from Florida
Another Snail from Florida

Letter 3 – Terrestrial Snail from Borneo

 

Subject: Strange Tentacled Mountain Snail
Location: Mulu National Park, Borneo
May 18, 2014 7:16 am
On my recent climb to the Pinnacles limestone formation at the Mulu National Park, I encountered this strange grey and red snail displaying two long grey tentacles emerging from its back at an elevation of about 1000 metres above sea level. I have not seen this snail elsewhere and I see it turn up again and again in pictures from blogs of other folks who have climbed the Pinnacles – but till date, no one was able to give a positive ID.
Signature: Yours sincerely, Kok Sen Wai

Terrestrial Snail
Terrestrial Snail

Dear Kok Sen Wai,
We can’t believe we are posting two requests for very unusual Terrestrial Snails in the same day.  The markings on the shell of your Snail are very similar to this example of
Naninia obiana from Indonesia that is posted to FlickR.  We did find a matching example on FlickR that is unidentified and Eric Hunt who posted the image made this observation:  “The snail had two structures that it rapidly wiped over the shell like it was cleaning it.”  There is also an image on Laura Loves It’s Blog and another example on FlickR.  We will try contacting Susan Hewitt who frequently assists in the identification of Molluscs on our site to see if she has any ideas.

Authors

    by
  • Bugman

    Bugman aka Daniel Marlos has been identifying bugs since 1999. whatsthatbug.com is his passion project and it has helped millions of readers identify the bug that has been bugging them for over two decades. You can reach out to him through our Contact Page.

  • Piyushi Dhir

    Piyushi is a nature lover, blogger and traveler at heart. She lives in beautiful Canada with her family. Piyushi is an animal lover and loves to write about all creatures.

17 thoughts on “Are snails insects? Debunking common misconceptions”

  1. Hi Daniel, Ah, another mollusk! This is Acanthopleura granulata (Gmelin, 1791), the West Indian fuzzy chiton. The shell plates of this chiton are actually brownish and are usually very eroded. The pink/purple color on this one is due to a layer of encrusting calcareous red algae. For more info see the Wikipedia article (which I put together.) Best wishes to you, Susan J. Hewitt

    Reply
  2. I wanted to add:
    1. That these chitons do move around, but only at night, grazing on microscopic algae which grows on the rock surface. Each one returns to its same spot on the rock at the end of the night.
    2. That the maximum size of this species is about 3 inches in length.
    3. There is a really excellent book on the chitons of P.R. called “Los Quitones de Puerto Rico” by Cedar I. Garcia Rios.

    Reply
  3. These things are cool. I guess you can eat them. They’re mostly protein. First challenge would be to pry them off whatever rock they’re attached to. Then you’d need to know how to cook them……anyone know a good chiton recipe? I’ve been looking everywhere!

    Also, I think some Caribbean local make jewelery out of there. I think they turn blue if you sand them. Not sure though, might have dreamed that lol

    Reply
  4. Chitons and cuisine:
    The previous comment about eating them intrigued me a little; Wikipedia briefly mentions their consumption in Tobago and elsewhere. I recall reading about Maori eating them, but that might have been only abalone.

    Some chiton species appear to be ‘meatier’ than others. There’s a vast discrepancy between the number of animal/plant species consumed around the world, and the number commercially consumed in developed nations such as the U.S. This dynamic raises a whole series of questions.

    Dave
    http://www.smallstockfoods.com

    Reply
  5. Hello Bruce. The first snail is Euglandina rosea, the “rosy wolf snail” — it is carnivorous, and eats other snails. The second snail is Zachrysia provisoria, the “garden provisoria”, which can be a pest as it enjoys fruits and vegetables. These snails are both native to Florida; neither species can survive in the wild in cold climates, but both species have been introduced to other tropical localities (either on purpose or by accident) with unfortunate effects.

    P.S. Sorry it took me so long to answer your question, but I have neglected to check WTB recently.

    Reply
  6. Hello Bruce. The first snail is Euglandina rosea, the “rosy wolf snail” — it is carnivorous, and eats other snails. The second snail is Zachrysia provisoria, the “garden provisoria”, which can be a pest as it enjoys fruits and vegetables. These snails are both native to Florida; neither species can survive in the wild in cold climates, but both species have been introduced to other tropical localities (either on purpose or by accident) with unfortunate effects.

    P.S. Sorry it took me so long to answer your question, but I have neglected to check WTB recently.

    Reply
    • The common name is actually the “garden zachrysia”; I am on Nevis, West Indies and currently half-brained from jet-lag.

      Reply
  7. Wow, what a fascinating snail! The soft parts are a lot more curious, interesting and distinctive than the shell and its markings (a yellow shell like this with a black band is found in several families). Right off the bat I have no idea what this is, as I am not very good on tropical land snails. I get the chance I will try to research it over the next day or so, but I may not have much luck.

    Reply
  8. Yay! I heard back from an expert, Harry G. Lee of Jacksonville, Florida. He says (as I expected) that the soft parts are the crucial thing for ID-ing this snail. He is pretty sure of the species, but says it could also perhaps be another species in the same genus. The species is sometimes called Nanina citrina or Naninia citrina, but it is correctly known as Xesta citrina (Linnaeus, 1758). It is in the family Ariophantidae. Harry says it is a “posterchild paleotropical pulmonate”! What an amazing little beast it is! The soft parts of the animal are a thousand times more interesting than the shell. By the way, this snail makes and uses love darts before mating. 🙂

    Reply

Leave a Comment