Adaptive Significance of Shell-hardness in Turtles by Amy Gallimore and King Amponsem

1. Eastern Box Turtles, Terrapene c. carolina Adaptive Significance of Shell-hardness in Turtles by Amy Gallimore and King Amponsem Close up of Apalone ferox head Apalone ferox, Flordia Soft-shell Turtle

2. Taxonomy Florida box turtle (Hard shell turtle) Terrapene carolina Chinese softshell turtlePelodiscus sinensis

3. Smooth Softshell Turtle (Apalone mutica) Soft-shell Turtles Adaptations • They greatly reduce and flatten their protective shells which result in decreased mineral needs and extra energy for the hard tissues • Improving camouflage by hiding in mud (Why do you think?) • Soft-shell turtles are able to fit into narrow crevices and cracks, and use these locations that no other tortoise is capable of using because of their pancake-like profile and flexibility • Hunting performance • overall increase agility and short-term swimming boosts. (What mechanism enables this?) • The soft-shell tortoise is lighter because their shells or “carapaces” have a lot of openings in them and less bone

4. Hard-shell Turtles Adaptations • When a hard shell turtle is threatened, it will crouch down and withdraw into its shell, rather than make a quick getaway such as the soft-shelled turtle • Hard shell turtles are not as prone to bites and lesions as a soft shell turtle and can withstand water pollution better because the skin is not as permeable. • They can withstand aerial environments and temperature change better than soft shell turtles Snapping Turtle,Chelydra serpentina

5. B. Bagatto and R. P. Henry conducted studies on Soft-shell Turtles and Hard-shell Turtles Concerning Gas Exchange, Diving Behavior and Blood Acid-base Status Apalone Spinifera, soft shell turtle Trachemys scripta, hard shell turtle Apalone Ferox, soft shell turtle

6. Respiratory Gas Exchange Trachemys scripta, (hard shell turtle) almost entirely dependent on aerial respiration

7. Respiratory Gas Exchange • Apalone ferox (soft-shell turtle)doubled its aquatic gas exchange rate and was significantly different when compared with the hard shell, T. scripta • Why? • The soft shell turtles have evolved to spend long periods of time under water. This enables them to become better predators and capture their prey such as crayfish and fish.

8. The soft shell turtles (A. ferox and A. spinifera) are able to dive at much greater lengths when compared to the hard shell turtle (T. scripta) • T. scripta is able to stay emerged the longest but at rest. However, the soft shell turtles (A. ferox and A. spinifera) are able to exercise and move without oxygen significantly better than the hard shell turtle (T. scripta )

9. The hard shell turtle takes significantly more breaths when emerged under water. This is when the T. scripta is exercising. This indicates that the hard shell turtle is using more energy to capture food when submerged underwater which is disadvantageous

10. The hard shell turtle has adapted to absorb large amounts of lactic acid produced after exercise. • How do they do this? • Compartmentalization! They are able to recover faster from intense anaerobic exercise because of intercompartmental transfers into their hard shell.

11. The soft shell takes a longer amount of time to recovery from intense anaerobic exercises, however is NOT significantly different

12. Work Cited: • Prtichard, Peter C.H. Evolution and Structure of the Turtle Shell. Flordia, 2008 • Carr, Archie 1952. Handbook of Turtles, New York. Cornell University Press. • Iverson, John B. 1992. A Revised Checklist with Distribution Maps of the Turtles of the World, Indiana. • B. Bagatto and R. P. Henry1999. Exercise and Forced Submergence in the Pond Slider (Trachemys scripta) and softshell turtle (Apalone ferox): Influence on Biodal Gas Exchange, Diving Behavior and Blood Acid-Base Status • http://www.unc.edu/~dtkirkpa/stuff/pancake2.html