1. Introduction to the Animal Kingdom
Biology 20

2. Which of these are animals?

3. Answer:
They ALL are!

4. Characteristics of Animals
Multicellular
Eukaryotic
Heterotrophic
Lack cell walls
Evolved to live in many different habitats

5. Animal Features

6. Feeding
All are heterotrophic and must digest their food (and excrete waste too!)
Very diverse in how they eat, digest, and excrete
Herbivore = eats plants
Carnivore = eats animals
Omnivore = eats plants and animals
Detritivore = feed on decaying organic material
Filter Feeders = aquatic animals that strain food from water
Parasite = lives in or on another organism

7. Respiration and Circulation
All take in oxygen and circulate it to their tissues (and give off carbon dioxide!)
How they do this is very diverse: very small animals rely on diffusion while larger animals have a circulatory system
Simple diffusion
Through skin
Lungs
Gills

8. Movement
Most animals have a body form that can move at some stage in its development
The evolution of nerve and muscle tissue lets animals move faster than organisms in any other kingdom

9. Support Animals support their bodies in different ways
95% of animals are invertebrates (without a backbone)
Many are covered with exoskeleton (tough outer covering that provides support and protects internal tissues)
Some have internal skeletons called endoskeleton
5% of animals are vertebrates (with a backbone)
Have an endoskeleton made of calcium carbonate, cartilage, bone

10. Sexual Reproduction Most animals reproduce sexually
Male animals produce sperm and female animals produce eggs
Hermaphrodites produce both sperm and eggs in the same body

11. Sexual Reproduction
Fertilization occurs when the sperm penetrates the egg to form a fertilized egg called the zygote
Internal fertilization occurs when the sperm and egg combine inside the body
External fertilization occurs when the sperm and egg combine outside the body (i.e. in water)

12. Asexual Reproduction
To increase their populations rapidly, some animals can reproduce asexually
They do so using one or more methods
Budding
Fragmentation
Regeneration (new growth from a lost body part if the body part contains enough genetic information)

13. Early Development Animals begin life as a zygote (fertilized egg)
The cells in the zygote divide to form the blastula - a hollow ball of cells

14. Tissue Development Gastrula
The blastula pinches inward to form three germ layers. This stage forms what is called the gastrula.
Inner layer is the endoderm which develops into the digestive organs and tract
Gastrula

15. Tissue Development
Outer layer is the ectoderm which become the nervous tissue and skin
Middle layer is the mesoderm which develops into muscle tissue and the circulatory, excretory, and respiratory systems

16. Body Plan Asymmetry - no pattern (corals, sponges)
Radial Symmetry - shaped like a wheel (starfish, hydra, jellyfish)
Bilateral Symmetry - right and left sides (humans, insects, cats)

17. Identify the Symmetry

18. Body Plan
Animals with bilateral symmetry also have an anterior (head end) and a posterior (tail end)
This body plan is called cephalization - an anterior concentration of sense organs
The more complex the animal becomes the more pronounced their cephalization

19. Body Plan
Animals with bilateral symmetry also have a dorsal surface (backside) and a ventral surface (underside or belly)

20. Body Cavities
Animals with bilateral symmetry have a gut, which is a sac inside the body or a tube that runs through the body, where food is digested
A sac-like gut has one opening – a mouth – for taking in food and disposing of wastes
A tube-like gut has openings at both ends – mouth and anus – and is a complete digestive system

21. Body Cavities
Between the gut and the outside body wall of most animals is a fluid-filled body cavity.
Two types:
coelom (SEE lum) is a fluid-filled body cavity completely surrounded by mesoderm
psuedocoelom is a fluid-filled cavity between the mesoderm and endoderm
An animal with a solid body that lacks a fluid-filled body cavity is called an acoelomate.

23. Segmentation Advanced animals have body segments
Even humans are segmented (look at the ribs and spine)!

24. Types of Animals & Evolutionary Milestones

25. Phylum Porifera (sponges) - multicellularity
Phylum Cnidaria (sea anemones, jellyfish, hydra) - tissues

26. Phylum Platyhelminthes(flatworms) – bilateral symmetry
Free-living Planarian
Parasitic Tapeworm
Phylum Platyhelminthes(flatworms) – bilateral symmetry

27. Phylum Nematoda (roundworms) - pseudocoelom
Phylum Annelida (segmented worms) - segmentation

28. Phylum Mollusca (clams, squid, snails) - coelom

29. Phylum Arthropoda (crustaceans, insects) – jointed appendages
This is the largest phylum in the animal kingdom and contains the most number of species

30. Phylum Echinodermata (starfish) – mouth and anus

31. Phylum Chordata (vertebrates) – spinal cord