Meeting Abstract
Armor in animals can defend against predators and serve as support for animal movement. Poachers (Agonidae), nested within the cottoid fish lineage, are differentiated from other sculpins by their heavily-ossified dermal armor. They have elongate bodies entirely covered by bony plates ranging in morphology from unadorned to intricately ornamented. We used micro-computed tomography (µCT) scanning to characterize regional variation in armor plating along the body of Agonopsis vulsa, in adults and across ontogeny. In addition to gross morphology, we used CT-phantoms (hydroxyapatite standards of known density) to examine differences in mineralization of these bony plates. A. vulsa cross-sections show staggered series of eight bony plates that encircle and repeat along the length of the fish’s body, forming eight longitudinal ridges. The arrangement and number of plates remains fixed throughout the individual’s life. Excluding the head, these bony plates cover the majority of the body except for a small ventral area between the pelvic fins. Dorsal and longitudinal ridges do not show gross wear, but ventral plates do, and they have a more flattened morphology. Dorsolateral plates generally have ~45% of their total surface area overlapping with adjacent plates, with the majority of overlap on the antero-posterior plates of sequential segments. Initial estimates of density, based on brightness values, show that plate bases are less dense than plate tips, while plate estimated density show greater variation in the middle of the fish’s body. By comparing A. vulsa with other poachers, we will discuss how the specific spacing and orientation of armor ‘tiles’ shapes the dexterity, resilience, and ecology of armored species.
