WYNEKEN, Jeanette; KELSO, Kate; NGUYEN, Thinh: Range of Movement, Morphological Constraint, and Swimming Performnace in Marine Turtle Flippers.

The swimming of sea turtles is distinct from that of other living turtle taxa. The primary stroke used during cruising is the powerstroke or subaqueous flight. This stroke has large dorso-ventral and medio-lateral components. The sea turtle powerstroke differs significantly from the paddling or rowing strokes used by swimming nonmarine turtles in its lack of a strong anterior-posterior movement. In the literature, discussions of the morphological differences in cheloniid and emydid shoulder structure as well as differences the lateral extent of the carapace, have been hypothesized to constrain movements of the limbs and the locomotor form. We documented range of movement in Caretta caretta, the loggerhead sea turtle, Chelonia mydas, the green turtle, and Trachemys scripta, the red-eared slider and the morphological chracteristics of the shoulder joint. Additionally, we documented changes in forward thrust production during powerstroking in young marine turtles. We examined the stroke to determine if range of movement was related to maximum forward thrust production. The extent of forward thrust changed through out the stroke with most individuals having two peaks of thrust production during each stroke cycle. Periods when the flipper had the greatest range of movement and when it’s movement was more resricted showed that there was not a strong relationship between range of movement and thrust production in most individuals. Hence, the constraint on range of movement does not automatically imply a constraint on function or swimming performance in the marine turtle example. This conclusion may not apply to a the mechanically different paddling stroke in freshwater turtles.