Mechanically constrained stereotypy in agonid escape responses

In armor design, there is often a trade-off between protection and mobility—a balance that may influence the evolution of biological armor. In this study, I investigated whether the distinctive bony armor plates of Agonid fishes, specifically that of the grey starsnout poacher (Bathyagonus alascanus), impose mechanical constraints on movement. Focusing on the C-start escape response, I used high-speed video to quantify maximum body curvature and changes in lateral body length during the behavior. To connect scale morphology to flexibility, I measured the length of adjacent lateral scales from micro-computed tomography (µCT) scans of bent and straight specimens. The resulting bent-to-straight length (BSL) ratio served as a proxy for lateral surface compression and closely matched the lateral length changes observed in C-start trials. These findings suggest that flexibility is plausibly constrained by scale morphology, contributing to stereotyped escape responses, although the fish rarely use their full bending capacity.

Name thesis:degree_name

M.S.

Level thesis:degree_level

Thesis

Discipline thesis:degree_discipline

Biology

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Feiler, Avalon

Contributors dc:contributor

• Anderson, Philip
• Fuller, Becky
• Tan, Milton

• biomechanics
• armor

Statement dc:rights

• Copyright 2025 Avalon Feiler

Language dc:language

en

Handle dc:identifier

https://hdl.handle.net/2142/132681

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/132681