1. Introduction to Animals

2. Characteristics of Animals
Heterotrophs
Multicellular
Eukaryotic
Cells lack cell walls

3. Types of Animals Invertebrates Chordates
More than 95% of all animal species
At least 33 phyla
Examples: sea stars, jellyfishes, worms, insects
Chordates
Fewer than 5% of all animal species
Phylum Chordata
Examples: fishes, amphibians, reptiles, birds and mammals

4. Phylum Chordata
Have the following 4 characteristics during at least one stage of life
Dorsal, hollow nerve cord
Notochord
Tail that extends beyond the anus
Pharyngeal pouches

5. Dorsal, Hollow Nerve Cord
Nerves branch from this cord at regular intervals
Nerves connect to internal organs, muscles and sense organs

6. Notochord Long support rod
Runs through the body just below the nerve cord
Most chordates only have in the embryonic stage

7. Pharyngeal Pouches Paired structures in the throat (pharynx) region
Fishes and amphibians: slits develop that connect the pharyngeal pouches to the outside of the body
The slits may then develop into gills that are used for gas exchange

8. Post Anal Tail
All chordates have a tail that extends beyond the anus at some point in their lives
The tail can contain bone and muscles and is used in swimming by many aquatic species

9. What Animals Do to Survive
Maintain Homeostasis
Feedback Inhibition (Negative Feedback)
Gather and Respond to Information
Obtain and Distribute O2 & Nutrients
Collect and Eliminate CO2 & Other Wastes
Reproduce

10. Body Symmetry No Symmetry Radial Symmetry Bilateral Symmetry
Animals have body parts extend from a central point
Bilateral Symmetry
Animals have distinct anterior and posterior ends and have right and left sides

11. Differentiation of Germ Layers
Endoderm
Innermost germ layer
Develops into the linings of the digestive tract & much of the respiratory system
Mesoderm
Middle layer
Develops into muscles & much of the circulatory, reproductive, & excretory systems
Ectoderm
Outermost layer
Produces sense organs, nerves, & outer layer of the skin

12. Formation of a Body Cavity
Acoelomates
Invertebrates that lack a body cavity altogether
Pseudocoelomates
Invertebrates that have a body cavity only partially lined with mesoderm
Coelomates
Complex animal phyla that have a true body cavity (coelom) lined with mesoderm

13. Patterns of Embryological Development
Zygote
Fertilized egg
Blastula
Hollow ball of fells that develops when a zygote undergoes a series of cell divisions
Protostome
An animal whose mouth is formed from the blastopore
Deuterostome
Blastopore becomes an anus, and the mouth is formed from the second opening that develops

14. Segmentation
Many bilaterally symmetrical animals develop into repeated parts
Bilateral symmetry and segmentation are found together in many of the most successful animal groups
Simple mutations can cause changes in the number of body segments
Different segments can become specialized
HOX GENES

15. Cephalization Getting a Head!
Concentration of nerve cells at the anterior end of bilaterally symmetrical animals
Examples: arthropods and vertebrates

16. Body Plans

17. The Cladogram of Animals
Animal phyla are typically defined according to:
Adult body plans
Patterns of embryological development