Being one of the world’s earliest animals, the rich fossil records of snails reveal that they have been around since 550 million years ago (during late Cambrian period). Snails and slugs belong to the class Gastropoda, which is why they are known as Gastropods. Now before we deep dive into what do snails eat in the wild and in a fish tank, let’s explore a little bit about gastropods in general.
The class Gastropoda contains at least 65,000 species and it is the largest group within the phylum. They belong to a phylum of soft-bodied invertebrates called Mollusca, which contains around 85,000 to 150,000 extant species. Out of these, at least 60,000 species are Gastropods. A mollusk lacks internal skeleton and bones. Some of the other mollusks are octopuses, cuttlefishes, squids, and clams.
One of the reasons why Gastropods can survive in a diverse type of habitats is that they do not have huge appetites. As for the number of known species, Gastropods are second only to insects.
Common Garden Snail (Helix aspersa). Photo © Zachi Evenor. Image Source: Flckr
When we think of a teeny-weeny slimy snail, we almost always refer to land snails. However, there are also sea snails and freshwater snails.
Snails have a hard spiral shell made of calcium carbonate (which provides a record of a snail’s life), and into which they tend to retract for protection. Unlike snails, slugs do not have any such protective shell. Snails slide along smoothly with the help of a ‘muscular foot’.
In reality, snails secret out a lubricant (called ‘mucus’) along the way. By using this slime, they can move along on any terrain without doing any harm to their bodies. They locate food with the help of their sense of smell but they can’t hear at all. Finally, they are most active at night. Despite narrow habitat needs, snails still require moisture, shadows and decaying matter. If not, they will start to disappear.
What Do Snails Eat and Drink
A snail chomps on leaves with the help of its microscopic ribbon-like teeth, called radula.
Land Snails
Cyclophoroidea contains at least 7,000 species of land snails and it is the largest clade of this species.
A land snail eats a wide range of different foodstuffs. The diet of most land snails consists of herbaceous plant stems or leaves. However, some of them are carnivores too. New Zealand is home to some of the world’s largest land snails within the genus Powelliphanta.
These snails are most active at night and they are generalists. In other words, they will start feeding on whatever is available within their crawling distance.
Actually, there are tiny chemoreceptors on the tentacles of snails. They tend to locate their prey by using these.
Land snails usually consume fungi, soft bark, rotting vegetation, stems, algae, animal waste, and leaves.
Moreover, they also eat shells, eggs or flesh of other snails and slugs.
They usually snack on flowers, leaves and stems using their rasping tongues.
This snail species feeds on a huge range of vegetables, and seedlings, and such other soft plants.
Sea Snails
Sea snails (also known as ‘limpets’) occur all around the world and in mostly marshes or coastal waters. These conical-shell snails are omnivores.
Most of the marine snails are carnivores (like crown conch and Atlantic moon snail). They snack on bivalves, dead organisms and also other snails.
Photo © David Herbert. Ilanga laevissima. The fringe of small tentacles at the front of the animal (around its mouth) move along the ocean floor to pick up sediments and search for food. The long tentacles coming from the head and the sides can detect chemicals in the water and objects by touch. The small, black spot is its eye. Image Source: Natural History Museum
Some aquatic snails are herbivores (like the Florida fighting conch) and they tend to feed on algae and decaying organic matter.
With up to 2 feet long, horse conch is by far the largest aquatic snail in the United States. They consume bivalves and smaller marine snails.
Marsh periwinkles are pretty small species of marine snails. They have an average size of about one inch. They are herbivores and nibble on tiny bits of algae. When the tide is low, they worm their way across the mud and prey on algae. But in high tide (in marsh habitats), they pull themselves along the stalks of grass. Here, these critters gnaw at the plants and feed on fungi.
The Atlantic moon snail (also called the ‘shark-eye’) submerges itself in sandy flats and waits for its prey. Once the shark-eye finds the meal, they soften the prey by secreting out an acid. They usually suck up bivalves including oysters and clams. Besides, they also feed on other snails.
Freshwater Snails
There are about 5,000 species of freshwater snails. They thrive in ponds, lakes and streams.
A Red Ramshorn Snail. Image Source: Ask Nature
Freshwater snails usually love to prey on algae wafers. In addition to this, they also feed on the remains of fish food, sinking pellets, dead plant matter and other detritus.
Some of these snails are carnivores such as Assassin snails that feed mainly on other snails and decaying meat of dead animals. Mystery snails, nerite snails, rabbit snails, and assassin snails are just few of the species of freshwater snails.
Sources & Further Reading:
R. Platt, John. “Snails Are Going Extinct: Here’s Why That Matters“. Scientific American.
Solem, G. Alan. “Gastropod“. Encyclopedia Britannica, 12 May. 2020
“Facts About Snails“. Snail World.
“Sea Snails“. Florida Fish and Wildlife Conservation Commission.
“5 Sensational Sea Snail Species“. Ocean Conservancy.
“Types of Aquarium Snails“. AQUEON.
Bunje, Paul. “The Mollusca“. UCMP Berkeley.
“Land Snail Ecology“. Carnegie Museum of Natural History.
Vendetti, Jann, Ph.D. “A Microscopic Look At Snail Jaws“. Natural History Museum.
“Snails“. Eco Spark.
“Snails“. The Royal Horticultural Society.