1. Chapter 25 Biology Auburn High School p. 692 – 711
What is an Animal?
Chapter 25
Biology
Auburn High School
p. 692 – 711

2. Main Ideas of the Chapter
Animals are heterotrophs, digest their food inside the body, typically have a type of locomotion, and are multicellular
Animals have no cell wall
Embryonic development form a fertilized egg is similar in many animal phyla.

3. Main Ideas of the Chapter
Animals have a variety of body plans and types of symmetry that are adaptations
Animals may be asymmetrical, radially symmetrical, or bilaterally symmetrical
A coelom is a fluid-filled body cavity that supports internal organs
Flatworms and other acoelomate animals have flattened, solid bodies with no body cavities

4. Main Ideas of the Chapter
Animals such as roundworms have a pseudocoelom, a body cavity that develops between the endoderm and mesoderm.
Coelomate animals such as humans and insects have internal organs suspended in a body cavity that is completely surrounded by mesoderm
Exoskeletons provide a framework of support on the outside of the body, whereas endoskeletons provide internal support.
Animals probably evolved from colonial protists in the Cambrian period

5. 25.1: Typical Animal Characteristics

6. Characteristics of Animals
All animals are:
Eukaryotic, multicellular organisms
heterotrophic
have tissues that form organs
glycogen is form of starch storage
Must have a methods for obtaining food
Sessile – animals that don’t move from place to place

7. Characteristics of Animals
Must digest food in order to obtain its nutrients
Some animals digest their food in individual cells
Other animals digest their food in an internal cavity
Animal cells are adapted for specific functions
Example: blood cells, nerve cells and muscle cells

8. Development of Animals
Most develop from single, fertilized egg called a zygote

9. 25.2: Body Plans and Adaptations

10. What is Symmetry?
Symmetry refers to a balance in proportions of an object or organism.
Types:
Asymmetry –
animal that is irregular in shape
Most are sessile
Example is a sponge

11. What is Symmetry? Radial symmetry
Can be divided along any plane, through a central axis, into roughly equal halves
Adaptation of hydra

12. What is Symmetry? Bilateral symmetry
Can be divided down its length into similar right and left halves
Terms: anterior (head end); posterior (the tail end); dorsal (back surface); ventral (belly surface)
Example is a crawfish

13. Body Cavities in Animals
Acoelomate
Animals that have 3 cell layers but no body cavities
Example- flatworm
There is no space between the gut and epidermis in the acoelomate body plan.

14. Body Cavities in Animals
Pseudocoelom
A fluid-filled body cavity partly lined with mesoderm
Example: roundworm
There is space between the gut and epidermis in the pseudocoelomate body plan.
The body cavity is not lined with a membrane.

15. Body Cavities in Animals
Coelomate
A fluid-filled space that is completely surrounded by mesoderm
Example: segmented worm
There is space between the gut and epidermis in the coelomate body plan.
The body cavity is lined with a membrane that attaches to organs.

16. Animal Protection and Support
Exoskeleton
A hard, waxy covering on the outside of the body that provides a framework for support
Also provides protection
Prevents water loss

17. Animal Protection and Support
Endoskeleton
An internal skeleton that provides support inside an animal’s body
Protects internal organs
Provides a surface for muscles to pull against

18. Animal Protection and Support
Invertebrate
An animal that does not have a backbone
Examples: crabs, spiders, grasshoppers, and echinoderms

19. Animal Protection and Support
Veterbrate
An animal with a backbone.
All are bilaterally symmetrical, with endoskeletons
Examples: snakes, humans, fish, birds, reptiles