Aquatic Turning Performance in Juvenile Loggerhead and Green Sea Turtles

Area of Science:

• Marine Biology
• Biomechanics
• Animal Locomotion

Background:

• Sea turtles are expert long-distance swimmers, but their turning mechanics are poorly understood.
• Maneuverability is crucial for marine predators, yet turning strategies in sea turtles remain undefined.

Purpose of the Study:

• To investigate and define the turning mechanics of juvenile loggerhead sea turtles (Caretta caretta) and green sea turtles (Chelonia mydas).
• To compare turning performance, including turn radius and rate, between the two species and analyze limb coordination during turns.

Main Methods:

• Overhead video recording of juvenile loggerhead and green sea turtles performing yawing turns (rotational and translational) in a tank.
• Digital tracking of body points (rostrum, shell) and analysis of coordinates using custom MatLab code to estimate center of mass, turn radius, and angular velocity.
• Comparison of turning performance metrics, limb usage asymmetries, stroke frequencies, and flipper coordination between species and turn types.

Main Results:

• Significant differences in turning performance between loggerhead and green sea turtles were observed during rotational turns, but not translational turns.
• Limb usage asymmetries influenced angular velocity, and stroke frequencies differed significantly between turn types but not species.
• Loggerhead turtles initiated turns with both forelimbs more frequently than green sea turtles, which often used one forelimb.

Conclusions:

• Sea turtles' rigid body plan constrains their turning performance, similar to other rigid-bodied swimmers.
• Species-specific differences in flipper coordination contribute to variations in turning mechanics, particularly during rotational maneuvers.