Helicidae), we observed loping in members of five additional species of terrestrial pulmonates on concrete surfaces in the laboratory or in the field.
Loping had not, to our knowledge, previously been documented on vertical substrates (Pearce, 1989).
In most accounts of the locomotion of terrestrial gastropods, adhesive crawling is described as the normal locomotory mode, and loping is briefly mentioned as an unusual gait observed in just a few species, if it is mentioned at all (e.
Pearce (1989) summarized earlier ideas on the adaptive significance of loping in terrestrial pulmonates and suggested additional hypotheses of his own.
Loping snails move more rapidly than those using adhesive crawling, and loping is used only to escape enemies.
The second idea, that the primary function of loping is to flee enemies, suffers from an inherent weakness--loping of terrestrial gastropods has never been observed in the presence of a potential predator or other enemy (unless one considers the observer an enemy), but has been observed many times in the absence of enemies.
Loping decreases contact of the foot with "irritating" substances in certain substrates.
One major difference between the substrates that led to adhesive crawling versus those that induced loping is that the former are smooth and nonabsorbent, while the latter are rough, porous, and absorbent.
Our data allow us to quantify the potential benefit, in terms of conservation of mucus, of loping versus adhesive crawling on absorbent substrates like concrete.
We found that snails loping on concrete lost significantly more mass per area of mucus deposited than snails using adhesive crawling on acrylic.