No particular place to go

snail

Snails are gastropods–a word that translates as “stomach-foot” (Photo: Sally Crossthwaite, Creative Commons license)

.[reprint from March 2011]

Back when I lived in a large apartment community in this southwestern Virginia college town, I stepped onto the sidewalk one morning for a pre-breakfast stroll with my terrier-boy Dash, and saw a shimmering calligraphy on the concrete up ahead. Living in close proximity to undergrads had taught me to watch my step on Monday mornings… but this didn’t look like party residue.

Since it resembled writing, I thought for a moment it might be chalk—a message decipherable only by Greeks (the collegiate variety, not the folks in Athens)— but that didn’t explain the silvery quality of the text.

Finally, I drew close enough to solve the mystery. It wasn’t writing at all. The weather had finally turned warm enough, temporarily, for the local gastropod to take a stroll along a slime trail.

Wait… can you stroll when you have no legs and only one foot?

Stroll, stride, saunter… call it what you will. Snails get from point A to point B by gliding along a secreted track of mucus that hardens into a kind of Slip ‘n Slide® when exposed to air. The animals ride waves created by a band of muscles that travel along a foot that spans from the tail to the head. Surfing the slime they wander over roadways, through the woods, and up the walls of grandmother’s house or any other structure in their path.

snail trail

Snails secrete a mucus trail that serves as a kind of slo-mo Slip ‘n Slide® (Photo: Krstnn Hrmnsn, Creative Commons license)

Progress appears painfully slow to bipeds and quadrupeds, but the meandering trails suggest snail excursions are all about the journey, not the destination. You have to admit, they never rush—unlike many of their harried human neighbors.

Of course, it’s a smaller world for some. An average speed of 0.03 mph must be fast enough for a garden snail to get where s/he needs to go (snails are hermaphroditic, meaning they have both male and female sex organs, so s/he is particularly apt here).

Before you dismiss the lowly snail as too pedestrian to warrant admiration, you should know that the National Science Foundation supported a research collaboration between the University of California at San Diego (USA) and Stanford University (USA) to better understand the locomotion of snails and slugs, their shell-less cousins. The goal was to create robots that mimic snails, propelling themselves up and down walls, along ceilings, and across other challenging surfaces.

An examination of the mucus trail has proven fascinating as well. When common periwinkle snails are traveling along a vertical surface, the secretions have more adhesive qualities than when the animal is moving along a horizontal surface; the chemical structure of the mucus changes depending on the demands of the route.

But wait—there’s more!

A study by researchers at the University of Sunderland (UK) found that snails conserve energy by reusing slime trails. They will retrace their step to return to a previous resting site—a much safer strategy than hoping to stumble on an appropriate new location in time to avoid the dehydrating rays of the sun. Snails will also follow the trails of their cohorts to find dinner and a date. Essentially, they’re playing follow-the-leader.

So maybe a snail’s life is filled with fun and games. And wouldn’t you just love to see a group of gastropods do the Hokey-Pokey?

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© 2011 Next-Door Nature— no reprints without written permission from the author.

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