Meeting Abstract
Many vertebrates are armored over part or all of their body. The armor can serve several functional roles including defense/protection, offense, visual display, and communication of capability. Different roles imply different tradeoffs, for example defensive armor often trades resistance to attack for maneuverability. The poachers (Agonidae), 47 species of Scorpaeniform fishes, are a useful system for understanding the evolution and function of armor due to their high variety in extent of armoring. We report on an assessment of the amount of mineral in the armor compared to endoskeleton in a diversity of poachers, and an assessment of the damage type in armor across a growth series of one species of poacher. Using publically available CT scan data from 27 species from 16 of 21 genera of poachers we compared the armor to skeletal mineralization for a body region starting at the posterior end of the (first) dorsal fin going two times the body depth. The average material density (a measure of mineralization) of the armor in comparison to the skeleton ranged from 0.77 to 1.17, but the more impressive data is in the total mineralization (volume * average density). In some small, smooth scaled species, like Aspidophoroides olrikii, there was 10 times the material expenditure in the armor as in the endoskeleton. With 34 Agonopsis vulsa we carefully categorized the extent and type of damage to each of 35+ scales in the eight rows along the body. The ventral rows begin to show abrasive damage along the entire length of the fish. Impact damage to head and tail scales gets more severe and occurs at higher rates with age, suggesting the armor is not just for show.
