1. Introduction to animals
Introduction to Animals – Ch. 32

3. The Nature of Animals
Section 32.1

4. Classification: 95-98% of animals are invertebrates
Without a backbone
2-5% of animals are vertebrates
With a backbone

6. Animal Traits

7. Characteristics: Multicellular Eukaryotic Ingestive heterotrophs
All animals are:
Multicellular
Eukaryotic
Ingestive heterotrophs
Lacking in cell walls
Sexually reproductive
Able to move

8. 1. Multicellular Organization
Cell specialization: the evolutionary adaptation of a cell for a particular function
Tissue: group of similar cells that perform a common function
Cell junctions: connections between cells that hold them together as a unit

9. Levels of Organization
Molecule or compound
Atom
Organelle
Levels of Organization
CELL
Life begins
Tissue
Organ
Organ system
Organism

10. 2. Eukaryotic cells

11. 3. Ingestive Heterotrophy
Getting complex organic compounds (carbon) from sources other than the sun
Ingestion: taking in food usually in the form of an other organism
Digestion: the body’s process of extracting organic molecules from food

12. Lions Feeding (Ingestion)

13. 4. Lack of cell walls

14. 5. Sexual Reproduction & Development
Hermaphrodites: producing both eggs and sperm
Examples: worms & sponges
Most do NOT fertilize own eggs
Why not?
Zygote: diploid cell that results from the fusion of two haploid gametes
Undergoes differentiation (cells becoming specialized to perform a specific function)

15. Mating and Mating Behaviors
Female
Beetles Mating
Young
Courtship
Male
Mating and Mating Behaviors

16. Leeches Exchange Sperm During Mating

17. Parthenogenesis:
Females of some animals produce eggs, but the eggs develop without being fertilized!
New offspring will be all female
Example animals: some fishes, several kinds of insects, and a few species of frogs and lizards

18. Parthenogenesis in the Komodo Dragon
Video!

19. 6. Movement Sessile: attached & non-moving Sedentary: move very little
sponges
Sedentary: move very little
clam
Motile: animals that can move
humans
Ability to move depends upon interaction between nervous tissue and muscle tissues
Neurons: cells of nervous tissue

20. SESSILE
SEDENTARY
Chiton
Sponge
MOTILE
Cheetah

21. Video Origin of Animals: Animals came about in the water
Evolved from colonial protists:
Each organism had its own function (for the colony) much like each cell of the animal body has its own function (for the organism)
Video

22. Body Structure:
Symmetry is the arrangement of body parts around a central plane or axis
Asymmetry occurs when the body can’t be divided into similar sections
sponges

23. Radial symmetry when body parts are arranged around a central point
like spokes on a wheel
echinoderms
Most animals are sessile (attached) or sedentary (move very little)

24. Bilateral symmetry
when animals can be divided into equal halves along a single plane
right and left sides that are mirror images of each other
are usually motile
Show cephalization
concentration of sensory organs on the head (anterior) end

25. Body symmetry and cephalization Caption:
Figure: 22.1
Title:
Body symmetry and cephalization
Caption:
(a) A radially symmetrical body. Any plane that passes through the central axis divides the body into mirror-image halves. Animals in these groups lack a well-defined head. (b) Bilateral symmetry. The body can be split into two mirror-image halves only along a particular plane that runs down the midline. Animals with bilateral symmetry have an anterior head end and a posterior tail end. *

26. What type of symmetry is this?

27. Segmentation
When an animal body is composed of a series of repeating similar units
Example: earthworm (annelid)
Segments may look different & have different functions
Example: insects & crustaceans (arthropods)

28. Anatomical Terms: Dorsal: back surface of animal
Ventral: underside of animal
Anterior: front end of animal
Posterior: rear end of animal
Lateral: sides of animal
Medial: along midline of animal
Proximal: near to
Distal: away from

29. Label the parts: