Gastropod molluscs move along a thin mucus film using a single, muscular foot. Such adhesive mucus pedal locomotion is the most energetically costly form of transport in the animal kingdom, and the majority of this cost is due to mucus production itself. We have been developing a technique to study mucus production by single, freshwater snails that uses a common histological staining technique (periodic acid-Schiff’s stain) to visualize mucus trails on glass slides. Pixel grayscale values in digital photographs of slides then quantify amount of mucus present along a trail. In the present study, individual snails were allowed to move along a slide, were briefly disturbed, and then allowed to continue moving off the slide.
Results/Conclusions
Both pre- and post-disturbance trails were significantly darker on average, and had greater variability in pixel grayscale values, compared to background, indicating that trails were clearly visible. Regions where snails were disturbed were darker than pre-disturbance trails, indicating that snails produced more mucus on a very short time scale when disturbed. Post-disturbance trails were slightly less dark than disturbance regions but not significantly so, suggesting that snails maintained higher levels of mucus production after disturbance until they left the slides. This technique shows great promise in evaluating how snails modulate mucus production in response to environmental cues, and could thus greatly increase our understanding of the ecological energetics of these species in aquatic ecosystems.
