1. Section 1 The Nature of Animals
Chapter 32
Introduction to Animals
Section 1 The Nature of Animals

2. Chapter 32 Objectives Identify 4 important characteristics of animals.
List 2 kinds of tissues found only in animals.
Explain how the first animals may have evolved from unicellular organisms.
Identify four features found only in chordates.

3. Chapter 32 Characteristics
Section 1 The Nature of Animals
Chapter 32
Characteristics
Animals are multicellular heterotrophic organisms that lack cell walls.
Vertebrates have a backbone.
Invertebrates do not have a backbone.
95 percent of all animal species alive today

4. Multicellular Organization
Chapter 32
Multicellular Organization
Each cell depends on the presence and functioning of other cells.
specialization among cells
tissue
Organs
Multicellularity and cell specialization have enabled organisms to adapt to many environments.

5. Evolutionary Relationships in the Animal Kingdom
Chapter 32
Evolutionary Relationships in the Animal Kingdom
Phylogenetic diagram represents hypothesis for the relationship among members of the animal kingdom based on rRNA analysis.

6. Evolutionary Relationships in the Animal Kingdom
Chapter 32
Evolutionary Relationships in the Animal Kingdom
Notice on this diagram the locations of similarities in body tissues, body symmetry and embryonic development.

7. Chapter 32 Heterotrophic Sexual Reproduction
Characteristics of Animals
Heterotrophic
Sexual Reproduction
gametes fuse and offspring are genetically different
Movement
Most animals move at some point within their life cycle
As a result from the interrelationship of muscle tissue and nervous tissue, or neurons.

8. Origin and Classification
Chapter 32
Origin and Classification
The first animals may have evolved from colonial protists.
Taxonomists have grouped animals into several phyla by comparing their:
fossils
body symmetry
patterns of embryo development
macromolecules, such as rRNA

9. Chapter 32 Classification Chordates
All chordates have, at some stage in life:
a notochord, flexible rod on the dorsal part of the body
backbone
a dorsal nerve cord, hollow cord
brain and spinal cord
a postanal tail
pharyngeal pouches
outpockets of anterior digestive tract
gills for aquatic animals

10. Chapter 32 Patterns of symmetry
Body Structure
Patterns of symmetry
Symmetry is a body arrangement in which parts that lie on opposite sides of an axis are identical.
Types of symmetry are:
no Symmetry (asymmetrical)
radial symmetry
bilateral symmetry
cephalization
concentration of sensory structures in the anterior region

11. Radial and Bilateral Symmetries
Chapter 32
Radial and Bilateral Symmetries

12. Origins of Animal Tissues and Organs; Germ layers
All animals have true tissues except sponges
Chapter 32
Origins of Animal Tissues and Organs; Germ layers

13. The Animal Body: An Evolutionary Journey
Chapter 32
Body Structure and Relatedness
Biologists use similarities in body plans and patterns of development to help them classify animals and hypothesize about the evolutionary history of animals.
The Animal Body: An Evolutionary Journey