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Dryad

Hainan four-eyed turtles actively select suitable stones to masquerade according to their own morphology

Cite this dataset

Yu, Hongmin; Deng, Xinyi; Xiao, Fanrong; Shi, Hai-Tao (2024). Hainan four-eyed turtles actively select suitable stones to masquerade according to their own morphology [Dataset]. Dryad. https://doi.org/10.5061/dryad.h70rxwdsw

Abstract

Masquerade is a form of camouflage in which animals use their body size, shape, and coloration to resemble inanimate objects in their environment to deceive predators. However, there is a lack of experimental evidence to show that animals actively choose objects that match these body parameters. To explore how the Hainan four-eyed turtle, Sacalia insulensis masquerades using suitable stones, we used indoor video surveillance technology to study the preferences of juvenile S. insulensis for stones of different sizes, shapes, and colors. The results indicated that under normal conditions, during the day, juvenile S. insulensis preferred larger oval or round stones, while at night, they preferred oval stones that were closer to their own size, with no significant preference for stone color during either time. When disturbed (by a researcher swinging their arm back and forth above the experimental setup every hour to mimic a predator), the turtles showed a preference for brown stones that were closer to their size and oval in shape. These findings suggest that juvenile S. insulensis prefer stones that resemble their carapace size and shape to masquerade when undisturbed, and that this preference is reinforced when they masquerade to reduce the risk of predation. The preference for stones that resemble their carapace color is significant only when there is a disturbance. To the best of our knowledge, this is the first study to provide evidence that vertebrates can selectively choose objects that resemble their own morphology for masquerading to reduce predation risk.

README: Hainan four-eyed turtles actively select suitable stones to masquerade according to their own morphology

https://doi.org/10.5061/dryad.h70rxwdsw

This dataset records the preference of Sacalia insulensis turtles towards stones of different sizes, shapes, and colors during the day and at night, as well as the preference of Sacalia insulensis turtles before and after disturbance conditions in daylight.

Description of the data and file structure

The CSV file contains the counts of Hainan four-eyed turtles (Sacalia insulensis) observed on stones of different sizes, shapes, and colors during the day and at night. It also includes the preference of these turtles before and after disturbance conditions in daylight.

  • size: The data of size category of the stones.
  • shape: The data of shape category of the stones.
  • color: The data of color category of the stones.

  • Daytime: The count of turtles observed on the stones during the day.

  • Nighttime: The count of turtles observed on the stones at night.

  • Before disturbance: The preference of turtles before disturbance conditions in daylight.

  • After disturbance: The preference of turtles after disturbance conditions in daylight.

The DOCX file contains the results of G-tests performed on the data. The G-tests analyze the statistical significance of the preferences and counts of Sacalia insulensis turtles on different stone categories under various conditions.

Code/Software

All statistical procedures were conducted and generated in R 4.3.0 (R Core Team, 2023). All graphics were created using the ggplot2 package (Wickham, 2016) available in R 4.3.0 (R Core Team, 2023).

Funding

Hainan Provincial Natural Science Foundation of China