High-throughput simulations indicate feasibility of navigation by familiarity with a local sensor such as scorpion pectines

Scorpions have arguably the most elaborate “tongues” on the planet: two paired ventral combs, called pectines, that are covered in thousands of chemo-tactile peg sensilla and that sweep the ground as the animal walks. Males use their pectines to detect female pheromones during the mating season, but females have pectines too: What additional purpose must the pectines serve? Why are there so many pegs? We take a computational approach to test the hypothesis that scorpions use their pectines to navigate by chemo-textural familiarity in a manner analogous to the visual navigation-by-scene-familiarity hypothesis for hymenopteran insects. We have developed a general model of navigation by familiarity with a local sensor and have chosen a range of plausible parameters for it based on the existing behavioral, physiological, morphological, and neurological understanding of the pectines. Similarly, we constructed virtual environments based on the scorpion’s native sand habitat. Using a novel methodology of highly parallel high-throughput simulations, we comprehensively tested 2160 combinations of sensory and environmental properties in each of 24 different situations, giving a total of 51,840 trials. Our results show that navigation by familiarity with a local pectine-like sensor is feasible. Further, they suggest a subtle interplay between “complexity” and “continuity” in navigation by familiarity and give the surprising result that more complexity — more detail and more information — is not always better for navigational performance.