1. Invert Skeletal Systems

2. Types of Skeletal Systems
Changes in movement occur because muscles pull/push against a support structure, called the skeletal system
>Endoskeletons
>Exoskeletons
>Hydrostatic skeletons

3. Endoskeleton

4. Invert w/Endoskeletons (?)
-Echinoderms have calcite skeletons, that have calcium carbonate

5. Exoskeleton
[Will cover in detail much later]

6. Exoskeleton (nice ride!)

7. Hydrostatic Skeletons

8. Hydrostatic Skeletons

9. Hydrostatic Skeletons

10. Figure 5.2

11. Figure 5.3

12. Chaetae get lifted in regions of circular muscle contraction.
Hydrostatic Skeletons
Chaetae get lifted in regions of circular muscle contraction.
During longitudinal muscles contraction, chaetae anchor into the ground

13. Hydrostatic
Skeletons

14. Longitudinal muscle contractions allow for:
Bending
Undulating
Shortening / retraction of posterior end
Peristalsis
Coordinated / alternating contractions of circular and longitudinal muscles
Useful for forward propulsion and burrowing