Natural History Note – Upside Down Snails

Paddlers on quiet back waters may notice multitudes of snails floating upside down near the surface. However, close inspection will reveal that the snails aren’t floating, they’re crawling. The snails actually have the ability to attach themselves to the underside of the surface film and propel themselves forward; all the while feeding on the detritus and algae along the surface just as they would along the glass in a fish tank.  

Apparently the snails’ slime attaches to the water. They then can vary the thickness and texture of the slime trail by creating ripples in their foot as they lay it down. The varied texture allows the snails to propel themselves forward.  

Snail slime is being studied by various teams of engineers who hope to create robots that can walk up walls or over water. Other teams see the secrets of snail slime as providing clues for developing glues that stick to wet surfaces.