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Swimming and defense - competing needs across ontogeny in armored fishes (Agonidae)

Citation

Kolmann, Matthew et al. (2020), Swimming and defense - competing needs across ontogeny in armored fishes (Agonidae), Dryad, Dataset, https://doi.org/10.5061/dryad.v41ns1rsf

Abstract

Biological armors are potent model systems for understanding the complex series of competing demands on protective exoskeletons; after all, armored organisms are the product of millions of years of refined engineering under the harshest conditions. Fishes are no strangers to armor, with various types of armor plating common to the 400 million years of evolution in both jawed and jawless fishes. Here we focus on the poachers (Agonidae), a family of armored fishes native to temperate waters of the Pacific rim. We examined armor morphology, body stiffness, and swimming performance in the Northern Spearnose Poacher (Agonopsis vulsa) over ontogeny.  As juveniles, these fishes make frequent nocturnal forays into the water column in search of food, while heavily armored adults are bound to the benthos. Most armor dimensions and density increase with body length, as does body stiffness. Juvenile poachers have enlarged spines on their armor whereas adults invest more mineral in armor plate bases. Adults are stiffer and accelerate faster than juveniles with an anguilliform swimming mode. Subadults more closely approximate adults more than smaller juveniles, with regards to both swimming and armor mechanics. Poacher armor serves multiple functions over ontogeny, from facilitating locomotion, slowing sinking, and providing defense.

Methods

Armor morphometrics were measured from micro-CT data (Bruker Skyscan 1173) 

Swimming behaviors were captured using a GoPro Hero4

Swimming kinematics were analyzed using a custom MatLab script github.com/CDonatelli/PoacherArmorMechanics (Donatelli et al., 2017)

All data were statistically analyzed using the R programming language

Usage Notes

Scaling morphometrics & armor mineral density - use PoacherScalingCode.R w/ ArmorMorphometrics.csv or PoacherBMD_R.csv

 

For swimming kinematics - use PoacherNotebook.Rmd with PoacherKinematics.csv and PoacherMTSMerge.csv. Former are kinematics data, latter are stress/strain data from MTS.

 

ProcessedMTSData.zip are MTS stress-displacement data in the raw.

Funding

National Science Foundation, Award: 1712015

National Science Foundation, Award: 1852096

National Science Foundation, Award: 1759637