Quantitative analysis of experimental trackways of scorpions, tarantulas, and crayfish

ABSTRACT

Previous neoichnological studies with arthropods, especially arachnids, have often conducted experiments with only a small number of trackways produced in a subset of subaerial conditions. Thus, we conducted a comprehensive neoichnological study of scorpions (Hadrurus arizonensis), tarantulas (Grammostola rosea), and crayfish (Procambarus clarkii), under various moisture levels (dry, damp, wet drying, wet saturated, and subaqueous [or wading]) and horizontal, shallow, and steep slope angles. The invertebrates made a total of 473 trackway runs resulting in 489 symmetric trackway segments that were characterized and digitally measured. We analyzed the trackways using trackway parameter trend diagrams and non-metric multidimensional scaling (N-MDS) visualizations to compare trackway morphology among the sand moisture conditions. Results generally show imprints become progressively smaller, with more dotted multifid imprints going from loose to stiff sand. N-MDS showed trackway morphology overlapped among some conditions, including those with disparate water content (e.g. dry and wet saturated sand, or subaqueous and wet drying sand). Additionally, trackways consisted usually of a four-imprint series, though species- and condition-specific exceptions were found. Interestingly, the scorpions rarely dragged their metasomas, while the crayfish always dragged their tail fan except sometimes underwater. Our neoichnological photos and quantitative dataset provide a basis for future comparative ichnological studies.

KEYWORDS:

• Neoichnology
• trackways
• arthropods
• arachnids
• quantitative

Acknowledgements

The authors would like to thank the anonymous reviewers who helped greatly improve this manuscript, as well as Loma Linda University and the Geoscience Research Institute for supporting this research.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data availability statement

Annotated images of all experimental symmetric analyzed trackway segments, the primary data set with analyzed trackway segment parameters, and all Supplementary Materials are available online (DOI: 10.6084/m9.figshare.c.6778683) through FigShare (Clendenon & Brand, 2024).