What about Snails?
All photos courtesy Mike Davis
Mike Davis
I often walk around my neighborhood lake. Being an acute observer, I recently became aware of numerous snails in the surrounding foliage. Snails have always fascinated me, but seeing so many of these little creatures prompted me to research them and learn more.
Throughout the world, snails inhabit both land and aquatic environments. They are known for their unique physical characteristics, including a spiral shell and a muscular foot that allows them to move slowly along surfaces.
All land snails are gastropod mollusks, meaning they belong to the same phylum as octopuses (Mollusca). They are also members of the class Gastropoda, which includes all snails and slugs. Gastropod populations are second only to insects in numbers of named species. Their diversity is vast, with over 60,000 species, ranging in size from less than ¼ inch to the 12-inch Giant African Snail.
A key characteristic of mollusks is that they lack an internal skeleton or bones, but snails are not unprotected. In fact, the primary distinguishing physical characteristic of a snail is its spiral shell. Snails have a hard, protective shell coiled into a spiral shape. Composed of calcium carbonate, the shell grows with the snail throughout its life and protects its internal organs, including its lung—unlike aquatic snails, land snails breathe air. The snail continuously adds calcium carbonate to the shell's edge until it reaches its adult size. The shape and size of the shell can vary widely depending on the species, with some featuring ornate patterns or colors.
Snails can be found worldwide, even in Antarctica. Earth provides a wide variety of habitats for snails, allowing them to thrive in diverse environments and develop specific feeding habits. Gastropods have proven highly adaptable to changing environmental conditions and require only small amounts of food.
Snails move using their muscular foot, aided by secreted mucus. This mucus helps them slide across surfaces, maintain moisture, reduce friction, and protect their soft body structures. Land snails are incredibly slow, with speeds ranging from 0.5 to 0.7 inches per second, depending on the species. Their famous slowness has even inspired snail racing events in places like the UK!
Land snails cannot hear but rely on their eyes and olfactory organs. Their sense of smell, their most important sensory tool, helps them find food. Biologically, most snails are hermaphrodites, meaning they possess both male and female reproductive organs. However, they usually mate with a partner in the "traditional" manner. After a few weeks of gestation, the hatchlings emerge from their egg small and defenseless, making them highly susceptible to predators such as insects, animals, and birds. In the wild, snails live for about 3 to 7 years, but in captivity they can survive 10 to 15 years or longer.
Humans have consumed land snails for centuries. In parts of Europe such as France and Spain, they are considered a delicacy. However, caution is necessary when handling or eating snails because some harbor parasites that can cause severe diseases, such as meningitis. Proper hygiene is essential when handling snails, particularly those found in the wild.
When snails multiply excessively and damage crops or harm local ecosystems, they are considered pests. Some species can grow to the size of an adult hand, significantly increasing their feeding requirements. For this reason, it is important to manage and monitor snail populations carefully.
Scientists have discovered snail fossils dating back millions of years, making them one of the oldest-known animal species. By most estimates, snails have existed for around 600 million years!
A Medley of Snail Facts
Snails live everywhere on Earth, including Antarctica.
They dislike hot or dry weather. In such conditions, snails burrow underground and wait for cooler, damper weather.
Snails hibernate during winter.
They can be herbivores, carnivores, omnivores, or detritivores.
Herbivorous snails eat plants, algae, bark, chalk, and limestone.
Carnivorous snails feed on earthworms, slugs, and insect larvae, and they sometimes cannibalize other snails.
Photos courtesy Mike Davis
Snails have up to 12,000 teeth, all located on their tongue-like radula.
The smallest land snail can fit through the eye of a needle.
The largest living sea snail, Syrinx aruanus, can grow shells up to 35 inches in length and weigh as much as 40 pounds.
A snail’s mucus protects it from sharp objects, even razor blades!
Snails are the world's slowest pollinators, carrying pollen on their bodies and shells from bloom to bloom.
Most snails lay their eggs underground, although a few marine species give birth to live young.
Snails move at an average speed of 0.03 mph, covering approximately 158 feet per hour, making them one of the slowest creatures on Earth.
Snail Identification
Betsy Cross
Turns out that snail identification can be a little daunting. The best reference I could find was Max Anton’s Mollusk Man website, which is full of photos and detailed scientific information. After reviewing Mike’s photos and using iNaturalist and other resources to ID his photos, two species of land snails kept rising to the top of the list: the Brown Garden Snail (Cornu aspersum) and the Milk Snail (Otala lactea). Both of these snails are in the family Helicidae and are relatively close in size. They are both non-natives and appear to be distributed across North America, with Milk Snails being primarily distributed in Texas. Here’s how Anton describes them:
Brown Garden Snail: “The globular shell is brown or tawny with dark bands with light flecks. The surface is finely wrinkled and covered with a film-like periostracum that tends to flake off with age.”
Milk Snail: “The shell is milky white or cream colored, often with faint bands and fleck marks. Some forms have bold brown lateral bands and stripes.”
Regarding distinguishing features, these two snails have common shell characteristics with one exception, the Brown Garden Snail has a “white lip” and the Milk Snail has a “uniformly dark mouth.” These characteristics are easily seen in Anton’s online field guide photos. Since we’re unable to see the interior opening edge (lip/mouth) of the snails’ shells in Mike’s photos, it’s impossible to evaluate this differentiating characteristic. However, for the banner shot at the top, it could be the Brown Garden Snail because of its tawny brown shell, at least for the part of the shell that we can see in the photo. And for the others, I vote for the Milk Snail. They all seem to fit that description perfectly.
I never knew how fascinating snails could be until I spent an entire afternoon researching them. Perhaps a follow up article is in order, and especially if there’s a snail expert out there who would like to weigh in with identification tips on these photos and continue this thread of information. Consider the invitation open.
