1. Animal Diversity KEY FEATURES OF BODY PLANS ABBOTTS COLLEGE PAGE 73

2. DARWINS THEORY OF EVOLUTION  Organisms are descended from common ancestors  This theory guides scientists in their search for order in the astounding diversity of animal life on earth  The science of taxonomy names and classifies different species to illustrate this order

3. PHYLA  Animals can be grouped into phyla according to similarities in various features of their basic structure(body plan)  This makes it possible to understand the evolutionary development of the group Body plan = the general similarities in development, form and function among members of a particular phylum PAGE 73

4. The term phylum is one of seven major categories that are used to classify organisms. In order of broad to specific, these seven categories are: Kingdom, Phylum, Class, Order, Family, Genus, and Species. Carolus Linnaeus developed this system of classification in the 18th century The term phylum is one of seven major categories that are used to classify organisms. In order of broad to specific, these seven categories are: Kingdom, Phylum, Class, Order, Family, Genus, and Species. Carolus Linnaeus developed this system of classification in the 18th century

6. THE FEATURES OF THE BASIC BODY PLAN INCLUDE:  Body Symmetry  Number of tissue layers developed from the embryo  The number of openings in the gut  The presence or absence of a coelom (body cavity) and blood systems

7. BODY SYMMETRY The body plans of multicellular organisms are either asymmetrical, radially symmetry or bilaterally symmetrical Asymmetry: Having no symmetry Sponges PAGE 73

8. ASYMMETRY Having no symmetry Sponges PAGE 73

9. RADIAL SYMMETRY  the body parts are arranged around a central axis  and can be divided into mirror images by an imaginary line through any vertical plane

10. RADIAL SYMMETRY  Tubular, vase or bowled shaped animals that have a mouth at one end are usually radial symmetrical  Radial symmetry is common in sessile, free-floating or weakly swimming animals.  They need to interact with their surroundings equally well on all sides

11. BILATERAL SYMMETRY  the body can only be divided into mirror images by an imaginary line through one plane  If cut lengthwise, the y form left and right halves (mirror images)  Also have a top and a bottom  And a front and a back  This type of symmetry is suited to animals that move about

12. BILATERAL SYMMETRY  They show cephalization which allows them to become aware of the environments around them as they move forward  This increases their chance of finding food or predators Cephalisation = concentration of sense organs, feeding appendages and nervous tissue near the anterior end of the animal

14. CEPHALIZATION

15. TISSUE LAYERS  Germ layers formed from developed embryo(zygote)  Upper layer (ectoderm) forms the epithelium of the body surface (skin) and the nervous system  Lower layer (endoderm) forms the wall of the digestive system (gut)  Mesoderm is formed by an interaction between the ectoderm and endoderm

16. Diploblastic animals only have two layers of tissues Ectoderm and endoderm Triploblastic animals have three layers of ttissues Ectoderm, mesoderm and endoderm

17. Why is the development of mesoderm so important?  The development of the mesoderm was a tremendous evolutionary advancement  Mesoderm plays a role in the formation of tissues eg connective tissue, cartilage, bone  and organs eg reproductive organs  and systems eg blood and lymph sytems Page 74

19. NUMBER OF OPENINGS IN THE GUT  Single opening  Two openings PAGE 74 Gut = The alimentary canal or a portion thereof, especially the intestine or stomach.

20. NUMBER OF OPENINGS IN THE GUT  Single opening  Primitive animals  Sac like digestive cavity  Take in food and expel waste out of the same opening  Not an efficient system Porifera and Cnidarians

21. NUMBER OF OPENINGS IN THE GUT  Two openings  It allows food to be continually taken through the mouth, digested and the waste released from the anus  This body plan allows specialization of parts along the tube, such as a stomach, intestine, etc.

22. BODY CAVITIES/COELOM A coelom is an internal fluid filled body cavity that develops in the mesoderm of triploblastic animals The coelom separates the digestive tract from the body wall Diploblastic animals do not have a coelom In triploblastic animals we distinguish between: acoelomate, pseudocoelomate and coelomate animals PAGE 74

23. ACOELOMATE ANIMALS  These animals have no coelom (body cavity) in the mesoderm  Can be diploblastic or triploblastic

25. PSEUDOCOELOMATE  Have a body cavity,  Not seen as a true coelom because it is not completely in the mesoderm NOT IN TEXTBOOK ADD TO WORKBOOK

26. COELOMATE  Have a body cavity in the mesoderm  They are more advanced than acoelomate animals

29. ADVANTAGES OF A COELOM Allows space for larger and more complex organs and systems to develop eg digestive organs, muscular system, blood system and allows animals to reach a considerable size In soft bodied animals the fluid in the skeleton can act as a hydrostatic skeleton (against which muscles can act) Allows the digestive system and body wall to move independently PAGE 75

30. THE END