The Sound of a Wild Snail Eating (4 page)

Part 3
JUXTAPOSITIONS

The history of the . . . snail has been more copiously
considered than that of the elephant; and its anatomy is as
well, if not better, known: however, not to give any one object
more room in the general picture of nature than it is entitled
to, it will be sufficient to observe that the snail is surprisingly
fitted for the life it is formed to lead.

— O
LIVER
G
OLDSMITH
,
A History of the Earth and Animated Nature,
1774

7. THOUSANDS OF TEETH

The mouth of the snail is armed with a very formidable
instrument in the shape of a remarkable sword-like
tongue . . .
[
with an
]
immense number of excessively sharp
little teeth . . . The quantity of these teeth is incredible.

—
Dietetic and Hygienic Gazette,
1900

I
THOUGHT MY SNAIL’S
tendency to gently nod its head as it ate was just a personality trait—but there was more to it than that. Years later I would read in more depth about the life of terrestrial snails. I requested through inter-library loan the twelve-volume compendium
The Mollusca,
which covers the entire phylum of mollusks—soft-bodied creatures lacking a backbone—from the octopus with its humanlike intelligence down to the tiny snail.

The scientific name for a snail or slug—a mollusk with a single muscular foot—is
gastropod;
derived from Latin and Greek, the word means “stomach-foot.” The poet Billy Collins ends his wonderfully quirky poem “Evasive Maneuvers” with these lines:

[I] said the word
gastropod
out loud,
and having no idea what it meant
went upstairs and looked it up
then hid in the woods from my wife and our dog.

If the term
gastropod
startled Collins, I wondered what surprises awaited me in the pages of
The Mollusca.
Arriving in random order, the dusty gray volumes were so heavy that I propped them up against other books and read them lying on my side. As I skimmed slowly along, reading a little bit each day, I found that every scientific field, from biology and physiology to ecology and paleontology, was packed with insights on gastropods. The abundance of detail was astonishing, ranging from their complex teeth patterns to the biochemistry of their slime making and the intimate details of their species-specific love lives. Yet even with
The Mollusca
’s many volumes, a certain perspective on snail life was missing. Then I discovered the nineteenth-century naturalists, intrepid souls who thought nothing of spending countless hours in the field observing their tiny subjects. I also came across poets and writers who had each, at some point in their life, become intrigued by the life of a snail.

In the fourth century BC, in the
History of Animals,
Aristotle noted that snail teeth are “sharp, and small, and delicate.” My snail possessed around 2,640 teeth, so I’d add the word
plentiful
to Aristotle’s description. The teeth point inward so as to give the snail a firm grasp on its food; with about 33 teeth per row and maybe eighty or so rows, they form a multitoothed ribbon called a radula, which works much like a rasp. This explained my snail’s nodding head as it grated away at a mushroom; it also explained the odd squareness of the holes I had discovered in my envelopes and lists. As the front row of teeth gets worn down, a fresh new row is added at the back and the radula slowly moves forward, being completely replaced over the course of four to six weeks. Radulae are adapted to a particular snail’s diet and can be an identifying characteristic of a species.

With only thirty-two adult teeth, which had to last the rest of my life, I found myself experiencing tooth envy toward my gastropod companion. It seemed far more sensible to belong to a species that had evolved natural tooth replacement than to belong to one that had developed the dental profession. Nonetheless, dental appointments were one of my favorite adventures, as I could count on being recumbent. I could see myself settling into the dental chair, opening my mouth for my dentist, and surprising him with a human-sized radula.

Some snail species are predatory, and a few are even cannibalistic and will bore a hole through another snail’s shell or attack directly through an aperture. These snails have evolved fewer but longer teeth, which, rather sinisterly, they can fold out of the way to give more mouth room for ingesting their victims.

This particular trait gave me the shudders. Even though my snail was not cannibalistic, I would not want to meet up with it or any other snail that was humansized, which brought to mind Patricia Highsmith’s short story “The Quest for
Blank Claveringi.
” Avery Clavering, a zoology professor, hears about the mythical man-eating snails of Kuwa, and hoping to prove their existence and gain fame by naming the species after himself, he sets off in pursuit. Arriving in Kuwa, he finds the giant twenty-foot snails grazing on treetops. Then they notice him. He assumes that it will be easy to “escape from two slow, lumbering creatures like the—the what? . . .
Carnivora
(perhaps)
Claveringi.
” But the professor gets a little too close to his live specimens, and so begins the most peculiar, and certainly the slowest, chase scene ever to occur in literature. With the giant snails in leisurely but relentless pursuit, Clavering becomes exhausted and seeks shelter between some boulders. One of the snails seals its slimy foot over his refuge, nearly smothering him. Eventually he escapes into the sea, but the giant snails follow and the plot reaches its grizzly end.

8. TELESCOPIC TENTACLES

The [snail’s] tentacles are as expressive as a mule’s ears,
giving an appearance of listless enjoyment when they hang
down, and an immense alertness if they are rigid, as happens
when the snail is on a march.

— E
RNEST
I
NGERSOLL
, “In a Snailery,” 1881

W
HEN MY SNAIL
was active, its muscular head and foot were extended outside its shell, but at the slightest hint of a disturbance, it quickly withdrew them into the shell’s largest, outermost whorl. Its soft body, containing the vital organs—a lung, a heart, and a gastrointestinal system—was connected to its shell by an internal mantle, which also provided space for a water reservoir. It could store about one-twelfth its weight in water and thus, camel-like, survive stretches of dry weather.

About half of my snail’s respiration occurred through its skin, and the other half through a breathing pore—a little hole on its right side below its head. Called a pneumostome, this pore allows air exchange by diffusion, opening infrequently, maybe four times a minute, more or less, depending on the snail’s activity. As warm-blooded creatures, or
homeotherms,
we humans have to maintain a constant body temperature, but my cold-blooded
poikilotherm
snail’s temperature matched that of its changing environment. Thus it could get by on half the calories needed by a similarly sized mammal.

My snail was equipped with two pairs of tentacles: the lower pair were a quarter of an inch in length, while the upper pair were nearly half an inch long, with eyes at the tips. The snail could instantly retract its eyes through these hollow tentacles, which themselves retracted just as quickly into its head. “The first striking peculiarity [of the snail] is that the animal has got its eyes on the points of its largest horns,” exclaimed Oliver Goldsmith in 1774 in
A History of the Earth and Animated Nature.
And at the end of the nineteenth century, in
The Dawn of Reason,
James Weir explained more precisely that “the snail carries its eyes in telescopic watchtowers.”

When my snail was foraging for food or grazing on a mushroom, its tentacles quivered and twitched continuously. They stretched toward desirable smells but were instantly retracted from anything the least bit offensive. The snail could move its tentacles individually in nearly any direction up to a ninety-degree angle, sweeping them slowly back and forth and up and around, just as a boat under way in the dark swings its searchlights about to look for navigational marks.

While we humans have five senses, relying most heavily on vision to find our way, a snail relies almost entirely on just three senses: smell, taste, and touch, with smell being the most critical. My snail could not hear anything at all; it lived in a world of silence. Its “sight” was highly limited—just a general awareness of dark and light to help with orientation. Bright light might warn of a hotter, drier, and more challenging environment; dark suggested safer, cooler, more humid conditions. A sudden shadow might alert it to a predator.

It was its tentacles—which hold smell and taste receptors—that gave my snail its look of intelligence and purpose. So critical are they to a snail’s survival that, if injured, they can be regrown, just as a starfish can regrow an arm. In an article titled “In the Realm of the Chemical,” David H. Freedman explains:

The land snail . . . devotes about half its . . . brain to taste and smell affairs. It divides the job neatly between its two pairs of [tentacles]: one [upper] pair is waved in the air to pick up smells, while the second [lower] pair is dipped tongue-style into promising substances as a final check before ingestion.

Using the taste buds on its lower tentacles, my snail could distinguish between salty, bitter, and sweet flavors. The thousands of chemoreceptor cells along its upper tentacles were similar to those inside a human nose. Snails “see” the world through smell, the way many insects do, and they can detect aromas from a few airborne molecules.

In its native habitat, my snail determined the source of a scent and the distance from which it wafted based on wind speed and direction. There was no woodsy fragrance blowing through my room, and the snail, especially while it lived in the pot of violets, must have been surprised by the kaleidoscope of unfamiliar smells, the scent of humans, human food, tea, soap, paper, and ink.

Unlike the human nose, infamous for its secretions, the noselike tentacles of a snail are the
only
mucus-free part of its body. And compared to the stationary, side-by-side nostrils of a human, the snail’s two independent tentacle-noses give it a kind of stereoscopic sense of smell. I imagined a crowd of humans with smell receptors completely covering their arms, walking down the main street of a town. As they passed coffee shops, bakeries, and restaurants, their arms would wave wildly toward the aromas. Perhaps restaurant critics so endowed could, with the wave of an arm, report not just on their own entrée but also on those of other diners at nearby tables.

Though the snail had a sophisticated method of scent tracking, I wondered how it experienced a life so devoid of sight and sound. In its native woods, my snail could not see the moss over which it glided or even the plants it climbed. It could not see the trees, nor the stars overhead. It could not hear birdsong at daybreak, nor the midnight howls of coyotes. It could not even see or hear its own kin, let alone a predator. It simply smelled and tasted and touched its world.

The closest I could come to understanding the snail’s experience of its surroundings was in reading Helen Keller’s portrayal of the richness of smell and touch from her own human experience in
The World I Live In:

I am not sure whether touch or smell tells me the most about the world. Everywhere the river of touch is joined by the brooks of odor-perception . . .

. . . Touch sensations are permanent and definite. Odors deviate and are fugitive, changing in their shades, degrees, and location. There is something else in odor which gives me a sense of distance. I should call it horizon—the line where odor and fancy meet at the farthest limit of scent.

I wondered if my snail was aware of a scent “horizon” and how far the odor of a mushroom could float through the air. A snail’s navigation is complex, based on ever-changing odors, sources of darkness and light, a tactile sense of air movement, and, through the touch receptors on its single body-foot, a response to vibrations and types of terrain. This was how my snail mapped the wild woods from which it came, as well as the crate beneath the pot of violets, and the terrarium.

I
COMBED THROUGH SCIENTIFIC
gastropod literature, eager to know more about my companion. I learned that snails are extremely sensitive to the ingestion of toxic substances from pollution and to changes in environmental conditions, such as temperature, moisture, wind, and vibration. I could relate to this, as my dysfunctional autonomic nervous system made me sensitive to these things as well.

Since I was unable to tolerate most drugs, my doctor prescribed treatments at such minute doses that a pharmacist said he felt as if he were dispensing medication for a mouse. My body’s temperature regulation no longer worked. One moment I was chilled, and the next too hot; this made life as a cold-blooded poikilotherm seem appealing. Before my illness, I had slept like a log with no window shades drawn; now my room had to be pitch black at night. The sound of the telephone sent a tsunamilike shock wave coursing through me, so I kept the ringer turned off. I could listen only to music that was slow and continuous; anything with individually punctuated notes was too jarring. This restricted my entertainment to the calm of Gregorian chants at a barely audible level. I wondered if the snail could sense the vibrations through the air, and what the Benedictine monks would think of singing to a gastropod.