Support Structures and Systems in Animals.pptx

The Human Body is a beautiful creation, but what keeps us standing? We may have emotional and support structures and systems in our lives, but let's learn the support systems in our very own bodies.

1. Support Systems in Animals The Types of Skeletons

2. Do These Animals Have Skeletons?

3. Are the Skeletons of These Animals Made of the Same Material (Bone)?

4. Aims and Objectives of the Lesson: By the end of the lesson, learners should be able to: Differentiate between the types of skeletons; Provide examples of organisms that exhibit one of the types of skeletons; Provide at least 2 advantages and 2 disadvantages. 

5. Skeletons: The skeleton is the supporting structure of an organism. There are three types of skeletons: Hydrostatic skeletons (fluid-based); Exoskeletons (chitinous or mineralised outer shell); Endoskeletons (cartilaginous or mineralised support structure inside the body) .

6. Hydrostatic Skeletons: Found in many cold-blooded and soft-bodied organisms.  Consists of a fluid-filled cavity surrounded by muscles. In some animals, it is called a coelem and, in some animals, it is called a haemocoel.  The fluid presses against the muscles which in turn contract against the pressure of the fluid. The fluid can not be compressed and, thus, maintains a constant volume against which the muscles can contract. For movement to occur, the muscles in the body act against the fluid. 

7. Organisms With Hydrostatic Skeletons

8. Exoskeletons: Found in animals such insects, scorpions, spiders, crabs etc. An external skeleton that supports and protects an animal's body. Non-living and consists of a cuticle strengthened by chitin Crustaceans, e.g., crabs, have their exoskeleton further strengthened by calcium carbonate. Muscles are attached to the inside of the exoskeleton which provides the resistance needed for muscle action.  Exoskeletons act as hard outer coverings to animals. Large exoskeletons are called "shells".

9. Organisms with Exoskeletons

10. Endoskeletons: Found in all vertebrates and a few invertebrates (sea sponges). This type of skeletons is found inside the body. Can consist of bone (all vertebrates, except for sharks) or cartilage (sharks). Some endoskeletons consist of both bone and cartilage. Endoskeletons protect soft body tissues and allow for free movement, greater growth and strength. 

11. Organisms with Endoskeletons:

12. Advantages of Different Skeletons Hydrostatic Skeletons Exoskeletons Endoskeletons Water animals can increase in size because the support of water reduces effects of gravity, allowing them to float. Movement requires little energy because it is helped by water. Healing occurs faster because the fluid can be readily replenished. The exoskeleton provides structural support and shape. The exoskeleton allows effective protection. The exoskeleton forms the point of attachment of internal muscles needed for locomotion; providing better leverage for muscle action. Allows for growth with increase in size. The endoskeleton is jointed which allows for flexible movement and support. The endoskeleton has allowed for vertebrates to adapt to move in various of different modes of locomotion, e.g., running, swimming, flying, jumping etc.

13. Disadvantages of Different Skeletons Hydrostatic Skeletons Exoskeletons Endoskeletons The hydrostatic skeleton lacks surfaces for muscle (and limb) attachment. There is very little protection for the internal organs. Animals with hydrostatic skeletons must have a moist or water habitat to prevent desiccation. The final body is limited because if the animal increases too much, in size, the exoskeleton becomes heavier; making movement more difficult. The animal is vulnerable during the process of moulting. Since the exoskeleton is non-living, it does not grow with the animal and restricts the growth of the animal unless moulting occurs. There is no overall protection to the body (but vital organs are well protected). The endoskeleton consists of living tissue, so it is susceptible to infections and disease.