1. Discuss the fact that the human male contains a hydrostatic skeletal system in the penis, which fills with blood during erection and acts in the same way thauL™æe fluid-filled cavities of the hydra, planarian, and earthworm do.
2. Discuss why the exoskeleton system and its internal musculature works well for a small animal such as an insect but would not be feasible for an organism the size of a human.
3. Discuss the relative advantages and disadvantages of an endoskeleton and an exoskeleton.
4. Discuss the different structures of human bones (long, short, flat, and irregular) and see if students can tell where the different kinds are lob ™êd.
5. Discuss why it is important that there be constant breakdown and replacement of bone tissue, and discuss the problems encountered by astronauts and cosmonauts, who spend long periods in weightlessness, where bone tissue deteriorates.
6. Discuss the importance of calcium in bone formation, muscle contraction, and blood clotting, with emphasis on the problems of osteoporosis in older women and men.
7. Point out the different kinds of skeletons in
mollusksówith slugs h`„þg none, snails having a coiled
shell, clams and oysters having a bivalved shell, and octopuses
having none.