Animal Body Plans

1. Animal Body Plans

2. Components of Organisms What are the levels of body organization from simple to most complex?

3. Components of Organisms Cells---- Single cells with specific functions Tissues---- Groups of cells with same function Organs---- Groups of tissues with the same function Organ Systems--- Groups of tissues with the same function Organism--- All components working toward homeostasis

4. Evolution of Animal Body Plans Anatomical features in animals’ body plans mark the branching points on the evolutionary tree. For example, animals without tissues are grouped separately from animals with tissues, and animals without segments are grouped separately from animals with segments. Recall the relationships among animals on this tree are inferred by studying similarities in embryological development and shared anatomical features. However, molecular data (DNA, ribosomal RNA, and proteins) suggest other relationships among animals

5. Development of Tissues Which animals have no tissues? Tissues mark the first branching point on the evolutionary tree Sponges are the only animals without tissues They are on the no-true-tissues branch. All other phyla branch off from the tissues branch of the tree.

6. Body Symmetry • The first branching point off the tissues branch • Symmetry describes the similarity, or balance, among body structures • The type of symmetry defines the kind of movements the animals can make • Asymmetry • Radial Symmetry • Bilateral Symmetry

7. ASSYMETRY • NO SYMMETRY at all = their shapes are not regular • Examples: ?? • Sponges, corals

8. RADIAL SYMETRY • Some animals have two halves that look almost the same when the animal is divided along any plane through its central line • This is radial symmetry. • Examples: ?? • Jellies, sea anemones…

10. Crown Jellyfish

12. Soft Coral Polyps

13. BILATERAL SYMETRY • Animals with bilateral symmetry have two halves that look like mirror images when the animal is divided along only one plane through its central axis. • Examples: ?? • birds, dogs, humans…

14. Candy striped Annelid

15. Blue Spotted Sting Ray

16. Marine Flatworm

17. African Elephants BILATERAL ASSYMETRY

18. BILATERAL ASSYMETRY Which cell layers are involved in development? • Most animals with radial symmetry develop from two cell layers—the ectoderm and the endoderm • All animals with bilateral symmetry develop from three cell layers—the ectoderm, the endoderm, and the mesoderm

19. What is the body plan called CEPHALIZATION? • An animal with bilateral symmetry has a headend and a tailend.

20. What is the body plan called CEPHALIZATION? • An animal with bilateral symmetry has a headend and a tailend. • The head end is called the anterior end. • The tail end is called the posterior end. • When the nervous tissue and sensory organs are located at the anterior end, the body plan is called CEPHALIZATION • Most animals with cephalization move with their anterior ends first

21. What is the body plan called CEPHALIZATION? • An animal with bilateral symmetry also has a backside and an underside. • The backside is the dorsal surface. • The underside, or belly, is the ventral surface

22. Body Cavities • An animal with bilateral symmetry also has a gut where food is digested. • The gut is either a sac inside the body or • Atube that runs through the body

23. Body Cavities • A saclike gut has one opening: the mouth • The mouth takes in food and disposes of wastes • Examples: sponges, jellyfish, flatworms

24. Body Cavities • A tubelike gut has an opening at each end • Food is taken in at themouth and digested, nutrients are absorbed, and waste is then excreted through theanus.

25. Body Cavities Pseudocoelomate Acoelomate Coelomate

26. Acoelomate Pseudocoelomate Coelomate

27. Acoelomates An acoelomate (ay SEE lum ate) is an animal that does not have a fluid filled body cavity (it has only digestive cavity) This animal has a solid body with no circulatory system. Nutrients and wastes spread from one cell to another.

28. Pseudocoelomates The pseudocoelom (soo duh SEE lum) is a fluid filled cavity that forms between the mesoderm and the endoderm. This position limits tissue, organ, and system development

29. Coelomates Most animals with bilateral symmetry have a fluid filled cavity between the gut and the outside body wall called a coelom (SEE lum). The coelom and the organs within it form from the mesoderm. The coelom was an adaptation that enabled coelomates to develop larger and more specialized body structures for increased nutrient and waste transport.

30. Development in Coelomate Animals Coelomates branch into two lines of development: Protostomes Deuterostomes Biologists compare how embryos develop to decide if animals are closely related.

31. PROTOSTOME Development The mouth of a protostome develops from the firstopening in the gastrula. Also, during development, the mesoderm splits down the middle, forming a coelom between the pieces.

32. Deuterostome Development In a deuterostome, the anusdevelops from the firstopening in the gastrula. The mouthforms from anotherpart of the gastrula Also, during development, the coelom forms from two pouches of mesoderm.

33. Segmentation • A segmented animal has a series of sections that are exactly alike

34. Segmentation • A segmented animal has a series of sections that are exactly alike • Segmentation has two advantages: • Other sections might be able to perform the function of a damaged section, enabling the animal to survive. • Segments can move independently. This enables flexible and complex movement.