Snail

Quick Take

• Snails and slugs look nearly identical, but one biological detail makes them fundamentally different creatures. Most people, however, would probably guess wrong about what that detail is. See how they differ →
• Sea snail adhesive is so remarkable that scientists are trying to replicate it for a surprising medical application. Discover the adhesive secret →
• Many snails possess a reproductive trait that defies conventional biology, and this trait changes everything about how they breed. Explore their reproduction →
• Snails have survived winters for millions of years using a multi-step self-preservation technique most gardeners have never heard of. Learn their winter survival →

Belonging to the phylum Mollusca, snails are found almost everywhere in the world, from high mountains to botanical gardens to deep undersea rocks. In some parts of the world, these animals are kept as pets.

The shell is the defining feature of the snail. This is the one thing that separates them from the closely related slugs and sea slugs (although many slugs still have internal shell plates within their bodies). Since the shells contain most of the internal organs, snails cannot survive without shells.

5 Incredible Snail Facts

• These animals contain only rudimentary eyes and no ears at all. Instead, they interact with the environment around them through their sense of touch and their ability to detect vibrations.
• One of the more unusual facts is that many species are hermaphroditic, meaning that they possess both male and female reproductive organs.
• Snails can survive the harsh winter by living off their fat reserves. They have multiple lines of defense to protect their soft bodies as they hibernate: first, they dig a small hole in the ground, then they retreat into their shell, and finally, they seal off the entrance of the shell from potential predators.
• Some aquatic snails (like the nerites) have gills to breathe underwater; others retain both lungs and gills. The apple snail has a breathing tube that reaches the surface of the water.
• The sea snail has a natural adhesive that allows it to stick to rocks without being carried away by the surf. This has inspired some researchers to develop a kind of experimental medical glue for use in repairing heart defects.

Evolution and Origins

The snail evolved on the planet over 150 million years ago. Gastropods, cephalopods, and bivalves were thought to represent a group of species that coexisted throughout the Cambrian epoch.

The earliest land snail is considered to have arisen around 350 million years ago when land plants first began to require extremely moist conditions. Being able to survive on land required the snail, whose body is still primarily made of water, to endure periods of unfavorable conditions.

The earliest snail species first appeared in shallow seas, where gills made this way of life possible, and many freshwater and saltwater animals still rely on them. The Late Cambrian Era, or roughly 500 million years ago, is when the earliest gastropods are found in the fossil record.

Species, Types, and Scientific Names

Snails belong to the class Gastropoda. This is derived from two Greek words meaning “stomach” and “foot.” The class name refers to the position of the foot below the gut. Gastropods belong to the phylum Mollusca.

In terms of the number of species, they are the largest class within the phylum. About 24,000 species have so far been subject to classification, but there may be 85,000 or more species of gastropods in the world. These can be divided into a few general classifications:

• Land Snails — These are the most well-known and the most likely to interact with people. The majority of land snails fall within the sub-class of Heterobranchia, along with the slugs.
• Freshwater Snails — Represented by thousands of different species, including the apple snails and nerites, freshwater species primarily occupy rivers, lakes, and streams.
• Sea Snails — Elusive and rarely seen, most gastropods actually inhabit the deep seas and near coasts, an entire underwater world largely hidden from people. Sea snails are divided into a few different classifications, such as the Vetigastropoda and Caenogastropoda.

Appearance

While most people are familiar with the basic garden snail, the entire gastropod class contains an immense diversity of different appearances and forms. Apple snails, nerites, ramshorn snails, etc., all have their unique characteristics.

In terms of diversity, gastropods are second only to insects — though snails are not insects themselves. Most snails possess a soft, tube-shaped body, a muscular foot for locomotion, one or more pairs of tentacles emerging from the head, and small eyes at the tips of the main stalks.

The most conspicuous feature that all species share is the spiral shell. It is attached directly to the body and cannot be removed without killing the snail, since it contains most of the internal organs.

The shell consists of three different layers attached to the mantle. The hypostracum is the innermost layer, situated directly against the body, followed by the ostracum in the middle, and the periostracum as the outermost layer. The periostracum, which consists of several organic compounds, is the top layer and also gives the shell its color. Shells come in many different shapes, including cones, ears, spindles, and even completely unique patterns found nowhere else.

The largest known species is the Giant African Snail, which grows up to a foot long. The smallest species (Angustopila psammion) ever identified, which comes from northern Vietnam, is about 0.6 mm in diameter. Most species measure a few inches in size between these two extremes.

Is a Slug a Snail?

A slug isn’t a snail, even though they are the most similar-looking animals. Slugs are gastropods that live without shells. Their habitats and habits differ from those of snails. Since most slugs lack a shell, they tend to squeeze into tight places like under tree bark and rocks. These habitats help protect them from predators and are great places to lay eggs.

Habitat

These animals are found almost everywhere on the planet, including oceans, rivers, lakes, forests, mountains, deserts, and even botanical gardens. The thickness of the shell is directly related to the local climate conditions. In drier regions, snails have thicker shells to help them retain moisture. In wetter regions, they tend to have thinner shells.

Diet

One of the most interesting facts about the animal is the sheer diversity of different feeding strategies. Depending on the species, they run the gamut from herbivorous to carnivorous or even parasitic lifestyles. Marine species are more likely to be carnivorous or omnivorous, while land snails tend to feast exclusively on plant matter. Most species have rows of small teeth and a rough tongue called a radula to consume food.

Garden snails eat mostly leaves, vegetables, and flowers. However, they may also eat organic matter like dead worms or even other snails.

What eats the snail?

The animal provides a stable food source for all kinds of hungry birds and mammals. It is also raised and eaten by humans across many different cultures and places. In France, for instance, the edible snail is considered to be a delicacy called escargot.

What does the snail eat?

Most of these animals are herbivorous; they feed on leaves, stems, bark, fruits, and even algae. Carnivorous snails (mostly of the marine variety) also happily consume worms, fish, and even other snails. These animals obtain calcium from dirt and rocks to build their impressive shells.

Prevention

For most people, these animals are simply an intrinsic part of the environment, easy to ignore. But anyone who’s ever tried to maintain a botanical lawn or garden knows that they sometimes cause immense damage to plants, especially given that snails can live up to 10 years in the wild. Short of calling a professional, there are several things you can do to get rid of them.

The most humane solution is to put up a copper mesh barrier to repel them or try to remove them by hand. You should also try to eliminate any dark, shaded areas which might attract snails. If you’re not invested in a specific type of plant, then you might want to consider using snail-resistant plants like lavender, rosemary, and sage. Salt is another effective method to get rid of snails, but it also might increase the salinity of the soil, which can damage plants.

Snails as Food

It is very common for humans to eat snails. In French cuisine, edible snails are served as a delicacy. The practice of raising snails for food is called heliciculture; snails are often kept in dark wire cages with dry wood or straw. Once ready, the snails are prepared for cooking; once cooked, their texture becomes chewy yet tender.

Snails are often considered gourmet food, and several different species of land snails can provide a hearty amount of protein to disadvantaged communities around the world. Various snail species are valuable because they can feed large numbers of people at little cost. In fact, in some countries, giant African land snails are produced commercially for food.

Land snails, freshwater snails, and even sea snails are all eaten in many countries. In some parts of the world, snails are fried as satay, which is a dish called sate kakul. Even the eggs of some snail species are eaten much like caviar. Additionally, in Bulgaria, snails are baked with rice or pan-fried in vegetable oil.