Substrate Attributes Determine Gait in a Terrestrial Gastropod

Abstract

Some terrestrial gastropods are able to move using two gaits: adhesive crawling, where the entire foot is separated from the substrate only by a thin layer of mucus and the snail leaves a continuous mucus trail; and loping, where regions of the foot arch above the substrate and the snail leaves a discontinuous mucus trail. Loping has been interpreted as a means of rapidly escaping predators. We found that the pulmonate Cornu aspersum moved using adhesive crawling on dry acrylic or glass substrates, but loped on dry concrete or wood. Loping snails did not move more rapidly than snails using adhesive crawling. Snails moving on concrete secreted a greater volume of pedal mucus per area of trail than those moving on acrylic; locomotion on concrete thus requires greater expenditure of mucus than does locomotion on acrylic. Because loping snails deposit a smaller area of mucus per distance traveled than do snails using adhesive crawling, loping may conserve mucus when moving on porous, absorbent substrates. Members of several other terrestrial pulmonate taxa can also lope on concrete, suggesting that this plasticity in gait is widespread among terrestrial snails.

How fast is a snail’s pace? The influences of size and substrate on gastropod speed of locomotion

“…Recent work by Hemmert & Baltzley (2016) investigating the relationship between body size and speed across individuals within a species found that this relationship was orientation dependent. Consistent with findings by McKee et al (2013), they found no correlation between speed and body size when individuals moved horizontally but a negative correlation when individuals moved vertically. This is particularly relevant when observing locomotion in C. aspersum as this species feeds in trees as well as on the ground (Iglesias & Castillejo, 1999;Alvarez et al, 2009).…”

“…This makes the ability to move over many kinds of surfaces, which vary in texture, angle, and moisture essential for survival. Although it is accepted that C. aspersum is sensitive to the type of substrate they are moving across (Baur & Baur, 1990;Arnaud, 2003;Balbi et al, 2018), no study has directly investigated the effect of substrate on crawling speed, with most existing research producing contradictory results and observing trends indirectly when investigating gait choice (McKee et al, 2013;Munn & Treloar, 2016). For example, when investigating substrate-driven gait choice McKee et al (2013) found that routine speed did not appear to differ based on gait.…”

“…Although it is accepted that C. aspersum is sensitive to the type of substrate they are moving across (Baur & Baur, 1990;Arnaud, 2003;Balbi et al, 2018), no study has directly investigated the effect of substrate on crawling speed, with most existing research producing contradictory results and observing trends indirectly when investigating gait choice (McKee et al, 2013;Munn & Treloar, 2016). For example, when investigating substrate-driven gait choice McKee et al (2013) found that routine speed did not appear to differ based on gait. However, overall speed was quicker when individuals were adhesive crawling on glass than when loping on concrete (Parker, 1937; see McKee et al, 2013 for more information and a video outlining this behaviour).…”

“…For example, when investigating substrate-driven gait choice McKee et al (2013) found that routine speed did not appear to differ based on gait. However, overall speed was quicker when individuals were adhesive crawling on glass than when loping on concrete (Parker, 1937; see McKee et al, 2013 for more information and a video outlining this behaviour). In contrast, Munn & Treloar (2016) found that snails also adopted a loping gait and produced less mucus when moving across a rough surface (sandpaper), as opposed to PVC plastic (on which adhesive crawling was adopted), but average speed did not significantly vary across the two surfaces.…”

Quantifying the mechanics of locomotion of the schistosome pathogen with respect to changes in its physical environment

“…In organisms without extremities, crawling and squeezing are typically driven by the exertion of periodic waves of shear stress (i.e. traction stress) on the surrounding substrate (11)(12)(13)(14)(15)(16). Organisms relying on this locomotor mechanism can control the wave characteristics in order to adapt their migration to diverse properties of their environment, such as surface roughness, adhesiveness and confinement (14,(17)(18)(19)(20).…”