Slugs and slime on a stump, Oakland, CA

The Shimmering Slime Drawings of Snails and Slugs

It’s hard not to notice crushed snails on sidewalks. But I usually didn’t notice the subtle slime trails that emerged out of front yard gardens, where and slugs and snails glided along glittering lines of slime crisscrossing the sidewalk. These lines mapping where the little creatures have traveled are visible only for a moment, when the sun happens to light them up at just the right angle.

One trail in particular reminded me of the people who use the Map My Run app to leave trails in the shapes of a body part or to spell words, and after I saw it, I was suddenly tuned in to slug and snail drawings like never before. 

Garden snail trail that first caught my eye

This snail had drawn this penis-like shape in my path, and it had literally mapped its run, all in a slime mucus that is both disgusting and beautiful. I wanted to see and photograph more of these drawings, so I set out on regular slime hunts.

Slime trail hunting

I look for trails on sidewalks where both the garden and the sidewalk strip are overgrown with weeds or thick with tall flowers.

 The sun has to be at the right angle to catch the crystalline shimmer. Since gastropods are nocturnal, mornings have the freshest trails, and they catch the morning light and make the transparent slime visible.

I start going out at sunrise. At first, most of the ground is in shadow, and it’s hard to find a place where the sun touches down.

Sunrise Slug Scribble

I walked farther and faster than I’d planned, looking down streets for sunbeams at distant intersections, then crouching down near slug level to inspect every trail: an unexpected workout.

The search for a golden sidewalk is a race against the clock. As the sun climbs higher, more and more sidewalks glow, but the quality of light diminishes: the freakishly long shadows shorten and the orange sunlight cools to blue daylight even as the air temperature warms.

Animal trails

Covering so much ground in my slug hunt made me wonder what shapes I was incidentally making by chasing sunlit sidewalks. I knew I was leaving a digital trail via my phone anyway. I downloaded the Map My Run app and tracked my own path.

Not only was I meandering around the neighborhood like a snail, but in comparison to an actual runner, I was traveling at a total snail’s pace.

I wondered how others have been noticing or drawing attention to the creations made by animals. ArtNet news reports that artists showing work made with  ants who cut patterns in leaves and sheep who sculpt salt by licking it. Slug trails remind me especially of the grooves cut by beetles in wood.

Furniture beetle trails in wood. Source:

These designs are made for both practical and social reasons, calling to mind the line between something willed by a single being and something incidental to the daily routines of life. The shape and motion of snails themselves is highlighted in an this elegant installation made by attaching lights to snails themselves.

Deeper into Slime

I began to read about the slime itself, and discover that like all mucus, it is a liquid crystal, with some properties of liquid and some of solid.

Garden snail slime trail

It is both an adhesive, allowing snails and slugs to climb vertical surfaces, and a lubricant, protecting the slug’s body from the sharpest surfaces and allowing it to glide quickly. To save energy, slugs ride mucus laid by other slugs as a kind of a superhighway.


Snail slime is used in cosmetics, primarily as an anti-aging skin treatment.

Found under the Instagram hashtag #snailtreatment

The slime is so strong that it is capable of suspending two bodies as they mate. I witnessed this phenomenon in person last summer while visiting friends in Kansas. Each night, the outside of their house became a love shack for leopard slugs, where side penises emerged from their heads, twisted together, and ultimately created a twisted, pulsating flower shape.

Screenshot at the peak of leopard slug mating, August 2017. Lawrence, KS.

Snail and slug encounters

During my daytime slime trail hunting, the trails were usually empty.

Slug being discovered during the day. Note the difficulty of seeing the slug trail without sunlight.

I’ve seen two types of trails: large, thick dots, and small silvery scribbled lines. Once I caught the animals in action, it became clear that the thick dots were garden snails and the lines were small black or brown slugs.

Thick dots of a garden snail
Thin line of slug slime

At the end of one of my longest slime trail hunts,  I saw the snail itself in the act of laying down a fresh trail. After appreciating so many drawings, seeing the real snail left me a little star struck. The sunlight was coming through its translucent body, lighting it up.

All Photos by Emily Wick unless otherwise noted


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