The Sound of a Wild Snail Eating (7 page)

13. A SNAIL’S THOUGHTS

why
such careful consideration
snail?

— K
OBAYASHI
I
SSA
(1763 – 1828)

I
WAS CERTAIN THAT
my snail was just as aware of the details of its world as I was of mine, and so I began to wonder about its intelligence. As I crept through the pages of scientific gastropod literature, I found myself stuck to the page that describes a snail’s brain, which, depending on its species, has 5,000 to 100,000 giant neurons.

A snail has memory; it can learn new smells and tastes and retain the knowledge for weeks or months, adapting its behavior accordingly. “Too many people think . . . that snails have no brains at all,” writes the malacologist Ron Chase in their defense. Like humans, older snails tend to learn more slowly than younger ones. There are plenty of situations that scare a snail, and even scientists now use the term
fear
to describe a snail’s reactions to danger.

In 1880, an unknown author declared in an essay titled “Snails and Their Houses” that the snail “is by no means lacking in intelligence, but exemplifies the truth of the aphorism that still waters run deep.” Lorenz Oken, a German naturalist of the same century, waxed rhapsodic in his
Elements of Physiophilosophy:

Circumspection and foresight appear to be the thoughts of the [snail] . . . What majesty is in a creeping Snail, what reflection, what earnestness, what timidity and yet at the same time what firm confidence! Surely a Snail is an exalted symbol of mind slumbering deeply within itself.

Even contemporary malacologists seem to be aware of the complexity of an individual gastropod’s life. “Clearly, to achieve any real understanding of the life of a slug or snail, the whole life history must be taken into account,” explains A. J. Cain in his chapter in
The Mollusca,
“Ecology and Ecogenetics of Terrestrial Molluscan Populations.” The biologists Teresa Audesirk and Gerald Audesirk note just as respectfully in their own chapter, “Behavior in Gastropod Molluscs,” that “as investigators themselves learn to ‘think like a snail’ . . . ever more amazing feats of [snail] learning power are revealed.”

An account of a snail’s behavior in a tight situation intrigued me. It appeared in “Mental Powers and Instincts of Animals,” a chapter in Charles Darwin’s manuscript
Natural Selection:

Mr. W. White . . . fixed a land [snail] in a chink of rock . . . in a short time the animal protruded itself to its utmost length, & attaching its foot vertically above tried to pull the shell into a straight line; then resting for a few minutes, it stretched out its body on the right side & pulled its utmost but failed; resting again, it protruded its foot on the left side pulled with its full force & freed the shell. This exertion of force in three directions, which seems so geometrically reasoned, might have been instinctive.

Were
I
stuck in a chink of rock, I’d have tried a similar approach. This raises the unanswerable question of where instinct ends and intellect begins. My snail went about its life, moment to moment, much as I did, making decisions—or being indecisive—about food and shelter and sleep. If a snail can learn and remember, then it thinks, at least on some level; I was convinced of this. And until someone (preferably a snail) can prove otherwise, I will hold on to this belief. The life of a snail is as full of tasty food, comfortable beds of sorts, and a mix of pleasant and not-so-pleasant adventures as that of anyone I know.

Except for their remarkable romances, about which I would soon learn, snails lead solitary lives. Their behavior is considered intermediate in complexity, simpler than that of mammals and insects but more advanced than that of worms. I wondered if they communicated with each other at all. In
The Descent of Man,
in 1871, Charles Darwin recounted the observations of a scientific colleague:

Mr. Lonsdale informs me that he placed a pair of land-snails . . . one of which was weakly, into a small and ill-provided garden. After a short time the strong and healthy individual disappeared, and was traced by its track of slime over a wall into an adjoining well-stocked garden. Mr. Lonsdale concluded that it had deserted its sickly mate; but, after an absence of twenty-four hours, it returned, and apparently communicated the result of its successful exploration, for both then started along the same track and disappeared over the wall.

Did these two snails exchange tentacle touches? And if so, what information was relayed through physical contact, smell, and pheromones? Wouldn’t a lone snail, given the option, prefer proximity to another of its species to ensure procreation and gene survival? While contemporary malacologists do not believe that snails form any permanent attachments to one another, Lonsdale’s account, if true, hints at the possibility of gastropod kin selection, as a snail too ill to make its own pedal mucus could travel more easily over its companion’s trail to reach food and shelter.

Aphid parents living on a leaf transmit vibratory signals to their minute offspring to warn them of predators. And though it was assumed that ants do not communicate with auditory signals, scientists have just discovered that some species utilize substrate-born sounds. Even if the world of the snail is soundless, this does not preclude other communication methods. The biologist Roman Vishniac was always amazed at the individual personalities of, and the relationships and battles between, microscopic animals in a drop of pond water. How can any species, even our own, ever fully fathom by what means another species or animal group interacts?

I
RESPECTED MY SNAIL’S
intelligence, so it distressed me to peruse the Cooperative Extension’s snail-farming literature. Historically, snails have been a healthy food source and a medicinal remedy for nearly every illness. But learning how to fatten them up—especially after the cornstarch disaster—was unsettling. I avoided glancing toward my small companion as I read, fervently hoping that it did not have any sort of gastropod telepathy and, if it did, that it understood that it was most helpful to me alive.

The Romans, however, had no such scruples; they placed live snails in Eden-like gardens of lush vegetation surrounded by sinister water-filled moats, satiating a snail’s desires and preventing its escape. Still, were I a farmed snail, I’d choose ancient Rome’s fresh organic produce over today’s agribusiness diet of chemically raised GMO cornmeal.

Farmed snails unhappy with their lot in life have found ways to break free. In the mid-nineteenth century, Sir George Head described the single-minded survival instinct of snails for sale at a street market in Rome: “The proprietor,” Sir George commented, “is obliged to exert his utmost vigilance and dexterity in order to restrain their incessant efforts to crawl over the edge of the basket and escape.”

A U.S. Department of Agriculture’s snail-farming bulletin notes that confined snails may form an aggregate, their combined strength and skills leading to escape. I thought of hundreds of snails packed densely into shipping crates, en route to a restaurant where escargots grace the menu and boiling water awaits. With one purpose in mind, they join forces, push up with their muscular heads against the top of the crate, and pop the lid right off, gliding slowly but steadily toward freedom.

14. DEEP SLEEP

“I am going to withdraw from the world; nothing that happens
there is any concern of mine.” And the snail went into
his house and puttied up the entrance.

— Hans Christian Andersen,
“The Snail and the Rosebush,” 1861

A
SNAIL UNHAPPY WITH
its dining options or uncomfortable with the weather will go dormant. Its heart rate slows to just a few beats per minute, and its oxygen intake diminishes to one-fiftieth of its active use. Perhaps it was my insomnia combined with the way my unusable time kept evaporating, but of all the traits the snail acquired through evolution, dormancy seemed to be the very best. Like Sleeping Beauty, a snail may not wake until circumstances are favorable—though, like Rip Van Winkle, it may wake into a changed world.

During the summer months, if conditions become too dry, windy, or hot, or if food supplies are limited, a snail will go into a kind of dormancy called estivation. It climbs up a plant, tree, or wall to be away from the earth’s heat and beyond reach of predators or floodwaters. Finding a safe place, it attaches itself firmly with mucus, usually with the shell opening facing upward, which may alert it to weather changes. Then it seals up its entrance with a temporary door made of mucus. This storm door, or
epiphragm,
protects it from shifts in temperature and humidity. A snail may estivate for weeks or months, or even several years.

With winter’s colder temperatures and shorter days, instead of estivating, snails will hibernate, sometimes returning each year to a familiar site. In 1835, in his treatise
On the History, Habits and Instincts of Animals,
William Kirby described prehibernation chores:

Snails cease feeding when the first chills of autumn are felt, and . . . set about their preparations for their winter retreat . . . Each forms . . . a cavity large enough to contain its shell. The mode in which it effects this is remarkable; collecting a considerable quantity of the mucus on the sole of its foot, a portion of earth and dried leaves adheres to it, which it shakes off on one side; a second portion is again thus selected and deposited, and so on till it has reared around itself a kind of wall . . . It presses against the sides and renders them smooth and firm. The dome, or covering, is formed in the same way . . .

. . . [Thus] it sets about erecting its winter dwelling, and employing its foot both as a shovel to make its mortar, as a hod to transport it, and [as] a trowel to spread it duly and evenly, at length finishes and covers in its snug and warm retreat.

Once in its form-fitted burrow, rather than make a single, thin epiphragm, as it would for estivation, a snail set on hibernating makes a thicker epiphragm, and depending on its species and the severity of the winter, it may make several in a row, as Ernest Ingersoll details in his essay “In a Snailery”:

Withdrawing into the shell, the animal throws across the aperture a film of slimy mucus, which hardens as tight as a miniature drum-head. As the weather becomes colder, the creature draws itself a little farther in, and makes another “epiphragm,” and so on until . . . the animal [is] sleeping snugly coiled in the deepest recesses of his domicile.

These slime plates, explains the author of “Snails and Their Houses,” “act on the principle of double windows, enclosing a layer of air between each pair, and so effectually protecting [the snail] from the cold.”

I could not stop thinking about the making of epiphragms. Their design is specific to a snail’s species and to its local climate conditions. They may be thin and simple or thick and elaborate. Strategically located breathing holes may be incorporated, or they may be permeable to air. There is quite an art to the construction of these little doors, and justly so. Despite their temporary nature, a good door in severe weather makes the difference between life and death for a snail. An epiphragm is also personal, and its statement is definitive: the snail is home but is not accepting visitors.

A combination of increasing daylight and rising temperatures will break hibernation. “The snail, having slept for so long a season, wakes one of the first fine days of April, breaks open its cell, and sallies forth to seek for nourishment,” observes Oliver Goldsmith.

While many animals, including some humans, make long-distance seasonal migrations to avoid winter weather, a snail’s dormancy methods allow it to stay put—a good thing, given the short distance of an average snail’s excursions. The French poet Jacques Prévert wrote the “Song of the Snails on Their Way to a Funeral” about two snails that plan to attend a service for an autumn leaf that has fallen to the ground. They travel toward their destination, and when they finally arrive for the funeral, spring has come and all is happy again.

Even while dormant, some snails have continued their worldwide adventures. Here, from “Snails and Their Houses,” is my favorite nineteenth-century account of relocated sleeping snails:

Professor Morse records that he has seen certain species frozen in solid blocks of ice, which have afterwards regained their activity . . . Snails, imprisoned closely in pillboxes for two years and a half, have nevertheless survived; and a . . . snail from Egypt fixed to a tablet in the British Museum, twenty-fifth March, 1846, being immersed in tepid water, marvellously but completely recovered after an interval of four years.

I wondered what happened to snails during the last ice age, and so I asked the malacologist Tim Pearce if he thought a snail could outglide an advancing glacier. He speculated that some of the larger terrestrial snails might possibly outpace a very slow flow of ice. I thought of a tiny snail with a glacier bearing down on it. As the glacier slid closer, the temperature would drop. In response, the snail would dig a burrow and hibernate, and the glacier would flow right over it. Even a snail couldn’t last through a deep sleep of a hundred thousand years.

I
T CAME DOWN
to this: I envied my snail’s many abilities. I wished I could create an epiphragm at a moment’s notice and seal myself off from the challenges of the world. If I couldn’t, like a snail, have strength equal to many times my weight, I’d settle for just getting my normal strength back. If I couldn’t glide straight up a wall or sleep stuck to the ceiling, I wished I could at least walk upright with the rest of my species. I wanted to escape from the chink of illness in which I was stuck.

How wonderful it would be if we humans with illnesses could simply go dormant while the scientific world went about its snail-paced research, and wake only when new, safe medical treatments were available. But why limit such an amazing ability to the ill? When a country faced famine, what if the entire population could go dormant to get through a hard time in a safe and peaceful way until the next growing season came around?