2. A B C Bottom resting Feeding Swimming Courtship Hartman, 1979

3. Manatees Strategies to stay on bottom at low cost Dense and heavy bones Dense skin Large lungs Ballast

4. Maneuverability Pectoral flippers or tailfluke Contractions of hemidiaphragms Position in water column Pitch and roll

5. Rommel and Reynolds, 2000

7. Manatee diaphragm Rommel and Reynolds, 2000

8. Compartmentalization Need to be distinct muscular units Separated by connective tissue elements With separate sources of innervation Termed “ neuromuscular compartments ”

9. Hypothesis Manatee hemidiaphragms are compartmentalized.

10. Methods Gross anatomical studies

11. Connective tissue elements Phrenic nerve VC Bundles

12. Connective tissue elements VC Bundle

13. Connective tissue elements VC Bundles X X X

14. Multi-directional fibers M. Newson, 1996 Manatee Diaphragm Intrinsic Tongue Muscles

15. Conclusions VC bundles separate diaphragm into 1.0 cm-wide blocks Muscle fibers insert into VC bundles Branches of phrenic nerve innervate groups of blocks Compartments may be composed of groups of blocks

16. D. Perrine, 2001