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Marine Ecology Progress Series

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MEPS 682:153-167 (2022)  -  DOI: https://doi.org/10.3354/meps13936

Dermal denticle shedding rates vary between two captive shark species

Erin M. Dillon1,2,*, Anshika Bagla1, Kiera D. Plioplys1, Douglas J. McCauley1,3, Kevin D. Lafferty4, Aaron O’Dea2,5

1Department of Ecology, Evolution, and Marine Biology, University of California Santa Barbara, Santa Barbara, CA 93106, USA
2Smithsonian Tropical Research Institute, Balboa, Republic of Panama
3Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA
4Western Ecological Research Center, US Geological Survey, c/o Marine Science Institute, University of California Santa Barbara, Santa Barbara, CA 93106, USA
5Department of Biological, Geological and Environmental Sciences, University of Bologna, Bologna 40126, Italy
*Corresponding author:

ABSTRACT: Shark dermal scale (denticle) accumulation in the fossil record can provide information about the abundance and composition of past shark communities. Denticles are shed continuously, such that a single shark leaves a scattered composite of many isolated denticles in sediments. However, the rate of denticle shedding as well as how these rates vary among shark species with different life modes and their consistency over time are unknown, limiting the interpretation of denticle assemblages. To better understand the process of denticle shedding and calibrate the relationship between absolute shark abundance in the environment and denticle deposition in sediments, we captured denticles shed by 2 shark species in a large aquarium over 9 mo. We then simulated how these aquarium-derived shedding rates shape the relationship between shark abundance and denticle accumulation. Bonnethead sharks Sphyrna tiburo, a more active, benthopelagic species with small, thin denticles, shed 3.6 times faster on average than zebra sharks Stegostoma fasciatum, a more sedentary, demersal species with large, robust denticles. This pattern persisted when shedding rates were corrected by estimated denticle quantities, shark space use, and methodological factors (2.2- to 3.8-fold difference). Over the study, bonnethead shark shedding rates declined while zebra shark shedding rates increased slightly. Finally, denticle assemblage composition corresponded with the relative abundance of denticles on the body of each species, consistent with natural shedding rather than selective loss. Overall, we show that shark taxa contribute unevenly to the denticle record, indicating that shedding rate measurements can help inform and constrain ecological interpretations of denticle assemblages.


KEY WORDS: Shark · Dermal denticle · Fossil record · Denticle replacement · Abundance · Aquarium


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Cite this article as: Dillon EM, Bagla A, Plioplys KD, McCauley DJ, Lafferty KD, O’Dea A (2022) Dermal denticle shedding rates vary between two captive shark species. Mar Ecol Prog Ser 682:153-167. https://doi.org/10.3354/meps13936

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