1. Introduction to Animals

2. Think of an animal…
Did you think of an organism that has fur or a bony skeleton?
MOST animals have neither bones nor hair!!!
So…what are the characteristics that all animals have in common?

3. Animal Characteristics
Multicellular
Eukaryotic (with no cell walls!)
Heterotrophic

4. Dividing Animals Based on Habitat
Animals that live in the water are AQUATIC
Animals that live on land are TERRESTRIAL

5. Multicellular Organization
Most animals contain large numbers of cells
Humans contain 50 trillion cells!
In most animals, cells are specialized to perform different functions
cells  tissues  organs  organ systems
Cell specialization has allowed organisms to evolve and adapt to many environments

6. Animals are Heterotrophic
Heterotrophs must obtain complex organic material from other sources
The animal eats (ingests) and then digests.
Digestion extracts the carbohydrates, protein and lipids from the food eaten

7. Sexual Reproduction and Development
Sexual reproduction increases genetic variation
During the developmental process, the zygote undergoes many mitotic divisions
These identical cells must differentiate
Differentiation is the process of cell becoming different from each other and specializing

8. Gastrulation: step in development when major tissues (germ
layers) begin to develop Endoderm, Mesoderm, Ectoderm

9. Movement Most animals are able to move
The ability to move results from two types of tissues found only in animals: nervous tissue and muscular tissue
There are a few animals that are sessile
Sponges, corals

10. Origin and Classification
First animals arose from the sea
Taxonomists have grouped animals into several phyla based on evolutionary relationships
95% of animals are invertebrates!
(We will investigate 9 major phyla. Eight of these phyla include invertebrates and only Phylum Chordata includes the vertebrates)

11. Divisions of Animal Body Structure
Symmetry
Cephalization
Germ layers
Body Cavities

12. Symmetry
Symmetry refers to the consistent overall pattern of structure of an animal
Animals have three patterns of symmetry:
Asymmetry – no symmetry
Examples: Fiddler crabs,
Sponges (porifera)

13. Symmetry, Continued
Radial Symmetry – similar parts branch in all directions from a central point
Ex: sea star,
anemones
Bilateral Symmetry- similar halves on either side of a central plane
Ex: Butterflies, humans

14. Patterns of Symmetry

15. Most animals have a dorsal, ventral, anterior and posterior side or orientation.
Dorsal – top (topside or back)
Ventral – bottom (underside or belly)
Anterior – head
Posterior – tail

16. Cephalization Most animals exhibit cephalization
Cephalization: the concentration of sensory and brain structures in the anterior (near the head)
Animals with cephalization have a head!

17. Germ Layers
Germ layers are tissue types found in all animals except sponges (no true tissues)
Ectoderm
Mesoderm
Endoderm

18. Body Cavities
Most animals have a fluid filled space that forms between the digestive tract and the outer wall of the body during development
This body cavity is known as a COELOM

19. Human Body Cavities

20. After Gastrulation Deuterostome: blastopore becomes the anus
Protostome: blastopore becomes the mouth

21. Animal Diversity 95% Invertebrates (animals without a backbone)
Phylum Porifera (sponges)
Phylum Cnidaria (jellyfish & corals)
Phylum Platyhelminthes (flatworms)
Phylum Nematoda (roundworms)
Phylum Annelida (segmented worms)
Phylum Mollusca (mollusks)
Phylum Echinodermata (spiny sea creatures)
Phylum Arthropoda (insects & spiders)
5% Vertebrates (animals with a backbone)
Phylum Chordata (Fishes, birds, reptiles, amphibians and mammals)