10.25349/D9K32M
Dillon, Erin
0000-0003-0249-027X
University of California, Santa Barbara
Bagla, Anshika
University of California, Santa Barbara
Plioplys, Kiera
University of California, Santa Barbara
McCauley, Douglas
University of California, Santa Barbara
Lafferty, Kevin
University of California, Santa Barbara
O'Dea, Aaron
Smithsonian Tropical Research Institute
Data from: Dermal denticle shedding rates vary between two captive shark
species
Dryad
dataset
2021
FOS: Biological sciences
dermal denticles
denticle replacement
aquarium
shark abundance
Fossil record
Sphyrna tiburo
Stegostoma fasciatum
University of California, Santa Barbara
https://ror.org/02t274463
Schmidt Family Foundation
https://ror.org/014bj2y47
Alfred P. Sloan Foundation
https://ror.org/052csg198
2021-11-10T00:00:00Z
2021-11-10T00:00:00Z
en
https://doi.org/10.3354/meps13936
https://doi.org/10.5281/zenodo.5637265
450632 bytes
2
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
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 two shark
species in a large aquarium over nine months. 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 each species’ body, 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.
This dataset includes: (1) shark dermal denticle (scale) and tooth
accumulation measurements in a controlled aquarium tank containing five
sharks and (2) accompanying observations of shark behavior in the same
aquarium tank. Data were collected from captive sharks in the Tropical
Pacific Gallery at the Aquarium of the Pacific (Long Beach, CA) between
2018 and 2020. The ~1,325,000 L tank housed two bonnethead sharks (Sphyrna
tiburo) and three zebra sharks (Stegostoma fasciatum) during the study,
permitting measurements of denticle shedding rates from two shark species
with different life modes and denticle morphologies. Shark denticles (and
teeth) were recovered from replicate sand-filled trays placed in three
locations in the tank over a nine-month-long period. Denticle accumulation
was collected at multiple time points to measure sub-annual temporal
variability in shedding rates. Denticles were classified to species and
functional morphotype to compare shedding rates between the two shark
species in the tank and examine whether certain denticle morphotypes were
preferentially shed. Denticle preservation was scored to document their
condition around the time of shedding. Lastly, behavioral surveys were
conducted to assess how patterns of shark activity, space use, and
interactions with the tank environment varied between species and, in
turn, might have influenced denticle shedding. Together, these data
provide insight into the process of denticle shedding and can be used to
explore the relationship between absolute shark abundance and denticle
deposition in sediments. This dataset contains five csv files: “counts”,
“weathering”, “morphotype_id”, “teeth”, and “behavior”. Field attributes
for each csv file are described in the accompanying Metadata ReadMe file.