The Sound of a Wild Snail Eating (8 page)

Part 5
LOVE AND MYSTERY

Every single species of the animal kingdom
challenges us with all . . . the mysteries of life.

— K
ARL VON
F
RISCH
,
A Biologist Remembers,
1967

15. CRYPTIC LIFE

struck by a
raindrop, snail
closes up

— Y
OSA
B
USON
(1716 – 1783)

M
Y INITIAL SURPRISE
at learning about gastropod defense systems quickly turned to respect. Whatever one’s family and species, the world is thick with danger, and my snail needed all of its active and passive defenses. But the survival methods of one type of animal may seem strange to another.

Snail-eating predators come in all forms, from mammals of all sizes to amphibians, birds, and various insects, including ants, centipedes, beetles, and tinier parasites. Even a few species of spiders resort to dining on escargots, though as Simon Pollard and Robert Jackson point out in their chapter in
Natural Enemies of Terrestrial Molluscs,
venom injection by a spider requires “close contact . . . [and] tends to mean a face full of mucus, which, for most spiders, may be an unacceptable price to pay for a meal.”

My snail was downright savvy; some of its active defenses were so subtle that I wasn’t even aware they were strategic. Simple withdrawal into the shell not only provided physical protection but also gave the appearance that no one was home. My snail used this defense quite successfully on me the day it arrived in the pot of violets. Oliver Goldsmith notes this behavior:

The snail, thus fitted with its box, which is light and firm, finds itself defended, in a very ample manner, from all external injury. Whenever it is invaded, it is but retiring into this fortress, and waiting patiently till the danger is over.

A snail’s slow locomotive speed makes it seem vulnerable, but it may actually be a survival method, saving it from predators whose hunting activity is triggered by fast movement. The silence of its gliding also protects it from those who hunt by sound.

Being slimy is a complex defense system that goes well beyond the ability to repel a
Homo sapiens.
Large predators can’t get a grip on a slippery creature, and smaller parasitic insects may get stuck in the ooze or have their mouth parts gummed up. If the usual slime recipe isn’t enough of a deterrent, a special batch with particularly toxic and bad-tasting chemicals can be copiously produced on the spot. For a gastropod, survival of the fittest often means survival of the slimiest.

One well-evolved passive defense was evident in the way my snail’s earth-colored shell blended into its environment. I was constantly nonplussed by how the snail could vanish right in front of my eyes against the terrarium’s flora, even when it was moving.

Then there was my snail’s brilliant strategy of elusively changing its sleeping spots. It might be on its side, drawn into its shell beneath a fern frond, and thus not visible from above; or nestled against a rotting branch the color of its shell; or in a crevice, hidden by a bit of lichen. It was amazing how the snail, with virtually no sight, found such perfect hiding spots.

It was in Tony Cook’s chapter in
The Biology of Terrestrial Molluscs,
titled “Behavioural Ecology,” that I found the sentence that best expresses a snail’s way of life: “The right thing to do is to do nothing, the place to do it is in a place of concealment and the time to do it is as often as possible.”

E
VERYTHING ABOUT
a snail is cryptic, and it was precisely this air of mystery that first captured my interest. My own life, I realized, was becoming just as cryptic. From the severe onset of my illness and through its innumerable relapses, my place in the world has been documented more by my absence than by my presence. While close friends understood my circumstances, those who didn’t know me well found my disappearance from work and social circles inexplicable.

Yet it wasn’t that I had truly vanished; I was simply homebound, like a snail pulled into its shell. But being homebound in the human world is a sort of vanishing. When encountering acquaintances from the past, I sometimes see a look of astonishment cross their face, as if they think that they are seeing my ghost, for I am not expected to reappear. At times even I wonder if a ghost is what I’ve become.

16. AFFAIRS OF ASNAIL

The emotional natures of snails, as far as love and
affection are concerned, seem to be highly developed,
and they show plainly by their actions, when courting,
the tenderness they feel for each other.

— J
AMES
W
EIR
,
The Dawn of Reason,
1899

O
NE MORNING
I looked into the terrarium and was surprised to see a cluster of eight tiny eggs. They were on the surface of the soil, just under the edge of the birch log, and were the color and size of pearl tapioca. I wondered if they were fertile and if they would hatch. I watched with interest as the snail visited the egg site every few days to tend them. On several occasions, the snail appeared to hold each egg in its mouth for a little while to “slime” it, or so I presumed, and thereby keep it at the right moisture for hatching.

Woodland snails are hermaphrodites. While rare among mammals, this characteristic is common in the majority of other animal groups and in the plant kingdom as well. A snail may find a partner randomly or show a preference for age or size. They mate in late spring, early summer, or fall, after an elaborate and complex courtship. A terrestrial snail that has been isolated for a while can, rather conveniently, self-fertilize, thus founding a new colony and ensuring the survival of its genes.

By chance, the previous year, I had watched the sensuous scene of two Burgundy snails courting in a French meadow in the film
Microcosmos,
directed by the scientists Claude Nuridsany and Marie Pérennou. Bruno Coulais’ original music composition “L’amour des escargots” provides an operatic backdrop to the snails’ obviously pleasurable, lengthy, lusty, and slimy embrace.

In Patricia Highsmith’s short story “The Snail-Watcher,” the main character observes two snails in love and is enthralled:

Mr. Knoppert had wandered into the kitchen one evening for a bite of something before dinner, and had happened to notice that a couple of snails in the china bowl on the drainboard were behaving very oddly. Standing more or less on their tails . . . their faces came together in a kiss of voluptuous intensity.

Fascinated by what he’s seen, Mr. Knoppert begins to read everything he can find on snails:

[He came] across a sentence in Darwin’s
Origin of Species
on a page given to gastropoda. The sentence was in French . . . [and] the word
sensualité
made him tense like a bloodhound that has suddenly found the scent.

I decided to follow in the research footsteps of Mr. Knoppert. Since he had turned to Charles Darwin for information on snail romance, so would I. My own research suggested that Mr. Knoppert may have been looking in the wrong book, as it was in
The Descent of Man
that I found the sentence, in the chapter on molluscs. It was a quote from Darwin’s colleague the Swiss American zoologist Louis Agassiz. Apparently too explicit for Victorian England, Agassiz’s observations had remained in the language of romance. The sentence did not contain the word
sensualité,
but it left me as curious as Mr. Knoppert, so I sent the quote off to several French-speaking friends with the resulting translation: “Whoever has had the opportunity to observe the lovemaking of snails will not question the seductiveness of their movements and airs, which anticipates the amorous embrace of these hermaphrodites.”

The Victorian naturalists were eager to weigh in on a snail’s love life. “The snail is, in fact, a very model lover. [It] will spend hours . . . paying attentions the most assiduous to the object of [its] affections,” proclaimed the author of “Snails and Their Houses.” Also smitten, the naturalist Lorenz Oken was much blunter: “Circumspection in feeling, dainty voracity, and immoderate lust appear to constitute the spiritual character of the . . . Snails.”

And then William Kirby mentioned something that sounded implausible: A snail’s “courtship is singular, and realizes the Pagan fable of Cupid’s arrows, for, previous to their union, each snail throws a winged dart or arrow at its partner.” I read more about these curious darts in Gerald Durrell’s autobiography
Birds, Beasts, and Relatives.
Durrell was ten years old and living with his family on the Greek island of Corfu when he happened into a forest just after a rainstorm: “On a myrtle branch there were two fat, honey- and amber-coloured snails gliding smoothly towards each other, their horns waving provocatively.” Durrell is intrigued:

As I watched them they glided up to each other until their horns touched. Then they paused and gazed long and earnestly into each other’s eyes. One of them then shifted his position slightly so that he could glide alongside the other one. When he was alongside, something happened that made me doubt the evidence of my own eyes. From his side, and almost simultaneously from the side of the other snail, there shot what appeared to be two minute, fragile white darts . . . The dart from snail one pierced the side of snail two and disappeared, and the dart from snail two performed a similar function on snail one . . . Peering at them so closely that my nose was almost touching them . . . [I watched as] presently their bodies were pressed tightly together. I knew they must be mating, but their bodies had become so amalgamated that I could not see the precise nature of the act. They stayed rapturously side by side . . . and then, without so much as a nod or a thank you, they glided away in opposite directions.

The “love darts” Durrell describes are tiny, beautifully made arrows of calcium carbonate, and they look as if they’ve been crafted by the very finest of artisans. They are formed inside the body of the snail over the course of a week and can be as much as one-third the length of the shell. The dart’s shaft is hollow and circular and, depending on species, may have four finlike blades, which are sometimes flanged; one end is harpoon sharp, while the other end comes to a flair with a corona-like base.

Some species produce a new dart for each mating; others withdraw and reuse them in successive matings. A particular species might keep just one dart in stock; others have a “pouch” with a pair or more. In
Practical Biology,
T. H. Huxley comments on these Cupid’s darts: “In the
spiculum amoris
. . . we have a structure, almost without parallel in the whole animal kingdom.”

The trauma of being hit by a dart, however, can sometimes put a snail off its courtship. Darts are not technically necessary for mating, and less than a third of all snail species are dart shooters. It is thought that the dart transmits a slime containing special pheromones that may improve the safe storage of the partner’s sperm.

A romantic encounter between a pair of snails can take up to seven hours from start to finish and involves three phases. First there is the lengthy courtship, in which the snails draw slowly closer, often circling each other, smooching, and exchanging tentacle touches. If they find they are not quite to each other’s liking, they may end their romance, but if things are proceeding well, then in some species, dart shooting occurs.

In the second phase, the snails embrace in a spiral direction and mate. Some species of snails simultaneously swap sperm, while others will be male or female at a particular mating and then reverse their roles the next time. Apparently being a hermaphrodite is not always easy; if two snails of a species that take on gender roles want to be the same gender simultaneously, a conflict may occur. Regardless of the method, and assuming all goes well, sperm is exchanged either internally or externally; depending on the snail species, it may be offered in elaborately designed and decorated packages called spermatophores.

Consummation is followed by the last phase, resting; the snails, still quite near each other, both withdraw into their shells and remain immobile, sometimes for several hours. Regardless of the mating methods of a particular species, fertilization occurs internally, after the lovers have parted.

In Highsmith’s story “The Snail-Watcher,” I could now understand why Mr. Knoppert’s wife “squirmed with embarrassment” when he “narrated snail biology to fascinated, more often shocked friends and guests.” Even Durrell is so surprised by what he sees that he consults his mentor, the biologist and zoologist Theodore Stephanides. Durrell’s brother Lawrence, previously bored with discussions of natural history, suddenly becomes quite interested:

“Good God,” cried Larry. “I think it’s unfair. All those damned slimy things wandering about seducing each other like mad all over the bushes, and having the pleasures of both sensations. Why couldn’t such a gift be given to the human race? That’s what I want to know.”

“Aha, yes. But then you would have to lay eggs,” Theodore pointed out.

“True,” said Larry, “but what a marvellous way of getting out of cocktail parties—‘I’m terribly sorry I can’t come,’ you would say. ‘I’ve got to sit on my eggs.’”

Theodore gave a little snort of laughter.

“But snails don’t sit on their eggs,” he explained. “They bury them in damp earth and leave them.”

“The ideal way of bringing up a family,” said Mother, unexpectedly but with immense conviction. “I wish I’d been able to bury you all in some damp earth and leave you.”

Gerald’s mother may have been impressed with another perk of snail parenting: a snail can keep its partner’s sperm alive for several months—even up to several years, if necessary—waiting for the best environmental conditions before proceeding to fertilize and then lay its eggs. My snail had probably encountered a romantic partner either very early in the spring or sometime during the prior year. The lack of predators and the provisions of large portobellos and a steady water supply were just the encouragement a prospective snail parent needed to go ahead with egg laying.

Eggs are usually laid below ground in several clutches of thirty to fifty each. My snail may have laid so few eggs and kept them above ground because the conditions in the terrarium were slightly too wet that week. Burying the eggs in such a circumstance might have been unsafe, since they could have burst as a result of osmosis.

As the embryonic snail grows, it absorbs some of the calcium from its protective eggshell. On hatching, it will eat whatever remains of the shell, and if food sources are scarce, it may also eat a nearby unhatched egg or two that would otherwise have been a sibling.