Written in Bone: Damage Patterns in Agonopsis vulsa Armor

• Main Author: Stewart, Morgan
• Format: Others
• Published: Scholarship @ Claremont 2019
• Subjects: biomechanics; damage patterns; armor; fish; Agonopsis vulsa; life history; Biology; Fine Arts
• Online Access: https://scholarship.claremont.edu/scripps_theses/1414; https://scholarship.claremont.edu/cgi/viewcontent.cgi?article=2277&context=scripps_theses

Naturally occurring armor has evolved in many different classes of organisms, often in response to predation, although other factors may play a part. In this study, the scales of the benthic armored fish Agonopsis vulsa were examined for damage patterns in order to illuminate the life history and environmental interactions of the fish. Scales from the fish were systematically destroyed in the lab, and observations made from the damaged scales were used to create a categorical damage rating, which was applied to 34 specimens ranging in trunk length from 2.3 cm to 14.2 cm. The specimens were rendered as three-dimensional digital models after being scanned with a micro-CT scanner. During data analysis, the damage categorization was simplified to a binary of damaged vs. undamaged and statistical significance of damage was calculated using probability loop simulations. Statistically significant damage was found in a few small clusters across the ontogeny, consistent with predation and intraspecies competition. This study is also suggests that the flattening of ventral scales in A. vulsa is not congenital. The scales are most likely ground down by constant friction against the sea floor over the lifespan of the organism.