1. CHAPTER 32 – ANIMALS

2. 32-1: The Nature of Animals
Two types of Animals:
Vertebrates
Animals with a backbone
Invertebrates
Animals without a backbone
Accounts for more than 95% of all animal species

3. Characteristics of Animals
Animals are:
Multicellular
Heterotrophic
Lack cell walls
Commonalities among animals:
Sexual reproduction
Movement

4. Characteristics of Animals
Multicellularity
Contains lots of cells
Estimated: humans = 50 to 100 trillion
Without M.C. – large #of animals would not exist
Cells are dependent upon each other for presence of and/or functioning of other cells
Biological hierarchy

5. Characteristics of Animals
Divisions of Labor:
Specialization
Adaptation of a cell for particular function
Example: building a house
Cell junctions
Connections between cells for communication
Cells together as a UNIT
Cells combine to form different types of tissues, organs, organ systems
MC + cell specialization have enabled organisms to evolve + adapt to many environments

6. Characteristics of Animals
Heterotrophy
Must obtain energy + nutrients by taking in organic molecules, usually other living things
Known as ingestion

7. Characteristics of Animals
Sexual Reproduction + Development
Fusion of gametes – sperm + egg
Known as a zygote – diploid cell
Undergoes continuous mitotic division
During this process, the cells become different from each other
Known as differentiation
Examples: bone cells, blood cells

8. Characteristics of Animals
Movement
Ability to move is a result of interaction between the nervous + muscular systems
Nervous cells, neurons, stimulate muscles to work

9. Origin + Classification
1st animals – arose in seas
Evolved from protists
heterotrophic + eukaryotics organisms
Colonial protists
Flagellated protists that lost movement (flagella)
Over course of evolution, cells in colony grew more specialized
First step towards MULTICELLULARITY
Taxonomy of Animals
Grouped according to phylogeny

11. Invertebrates (11 Phyla in Kingdom Animalia)
Body plans range from asymmetry + no tissues to bilateral symmetry + specialized body parts
Make up the greatest # of animal species

12. Chordates Phylum Chordata
All chordates have 4 features at some time during their development:
Notochord – a firm, flexible rod of tissue in the dorsal part of the body
Turns into backbone in vertebrate species
Dorsal nerve cord – hollow tube above the notochord
Turns into the brain + spinal cord
Pharyngeal pouches – small outpockets of anterior part of digestive tract
Turns into respiratory system (gills, lungs)
Postanal tail – muscle tissue behind the posterior opening of the digestive tract

13. A picture of a chordate…

14. Body Structure Symmetry
Body arrangement in which parts that lie on opposite sides of an axis are identical
Types of symmetry:
Asymmetry – no pattern
Example - Sponge

15. Body Structure - Patterns
Radial
Parts are organized in a circle around an axis
Examples: sea anemones, jellyfish, and hydra

16. Body Structure - Patterns
Bilateral
Two similar halves on either side of a central plane
Words used to describe bilateral animals:
Dorsal – back side
Ventral – belly side
Anterior – towards head
Posterior – towards tail
Cephalization – concentration of sensory + brain structures in anterior end of animal

17. Body Structure Germ Layers
Fundamental tissue layers found in the embryos of all animals
No tissues – sponges
2 germ layers – cnidarians + ctenophores
DIPLOBLASTS
3 germ layers – all other animals
TRIPLOBLASTS

18. Body Structure Body Cavities
Fluid-filled space that forms between the digestive tract and outer wall of body during development (known as a coelom)
No body cavity – flatworms
Having a body cavity allows organisms to move:
Muscles can contract
Does not allow internal organs to move
Reservoir and medium for nutrient/waste transport

19. Body Structure + Relatedness
Similarities in body plans and patterns of development allows organisms to be classified
Use of phylogenetic trees + cladograms
The branches on the tree represents phylogeny
The more closely related organisms are to each other, the closer the branches (recent common ancestor)
The further apart organisms are on the tree, the more distantly related they are thought to be