Pleated turtle escapes the box--shape changes in Dermochelys coriacea

Area of Science:

• Marine Biology
• Zoology
• Biomechanics

Background:

• Chelonians typically possess rigid carapaces, limiting physiological and ecological flexibility.
• The leatherback sea turtle (Dermochelys coriacea) is unique with its flexible carapace and reduced plastron.

Purpose of the Study:

• To investigate how foraging and breeding impact the carapace size and shape of female leatherback sea turtles.
• To understand the physiological adaptations of Dermochelys coriacea to different life stages.

Main Methods:

• Shell measurements (mass, girth, carapace length) were taken from adult female leatherbacks in Nova Scotia (feeding grounds) and French Guiana (breeding beaches).
• Direct and surface distances between carapace ridges were measured to assess shell distension.
• Changes in girth and inter-ridge distance ratios were analyzed in relation to nutritional and reproductive status.

Main Results:

• Turtles on feeding grounds (Nova Scotia) had greater mass and girth for a given carapace length compared to those on breeding grounds (French Guiana).
• Girth increased during the feeding season, and shell surfaces showed greater distension in foraging turtles.
• During the breeding season, girth decreased, indicating mass loss, while carapace shape remained relatively stable.

Conclusions:

• Female leatherback sea turtles exhibit substantial, rapid alterations in carapace dimensions in response to nutritional and reproductive demands.
• The flexible shell morphology allows Dermochelys coriacea to adapt to varying physiological states.
• These findings highlight the dynamic nature of sea turtle morphology and its ecological implications.