CH 26: Introduction to Animals

1. CH 26: Introduction to Animals Sec 1 and Sec 2

2. General Features of Animals • Animals are multicellular, heterotrophic organisms with cells that lack cell walls. • Humans depend on other animals for food, companionship, and to pollinate crops. • Most animals move to get food. But filter eaters, such as sponges and corals, catch particles of food that drift by in the water.

3. Kinds of Animals • Animals are often grouped as invertebrates or vertebrates. • Vertebrates make up only a subgroup of one phylum—Chordata. • Most animals are invertebrates.

4. Kinds of Animals, continued Vertebrates • Vertebrates have a cranium and an internal skeleton composed of bone or cartilage. • Vertebrates are chordates that have a backbone. • The backbone supports and protects a dorsal nerve cord and provides a site for muscle attachment. • Pg 625

5. CH26 Sec 2: Animal Body Systems

6. Key Ideas • Why is an animal's skeleton important? • What are the functions of the digestive and excretory systems? • What is the function of the nervous system? • Why are the respiratory and circulatory systems important? • What are two reproductive strategies of animals?

7. Support • An animal's skeleton provides support for the animal's body and location for muscle attachment. • Many soft-bodied invertebrates, such as jellyfish, have a hydrostatic skeleton • which is a water-filled cavity that is under pressure. • An exoskeleton is a rigid external skeleton that encases the body of an animal. • An endoskeleton is an internal skeleton made of bone and cartilage.

8. Digestive and Excretory Systems • The digestive system is responsible for extracting energy and nutrients from an animal's food. • The excretory system removes waste products from the animal's body.

9. Digestive System • A gastrovascular cavity is a digestive cavity with only one cavity. • The hydra has a gastrovascular cavity.

10. Digestive System, continued • In a digestive tract, food moves from one opening, the mouth, to a second, the anus. • Digestive tracts allow for specialization and more efficient digestion.

11. Digestive and Excretory Systems, continued Excretory System • The removal of wastes produced by cellular metabolism. • Simple aquatic invertebrates and some fishes excrete ammonia through their skin or gills. • Terrestrial animals need to minimize water loss.

12. Nervous System • Carries information about the environment through the body and coordinates responses and behaviors. • Nerve net • Ganglia • Brain

13. Hydra Nervous System

14. Flatworm Nervous System

15. Grasshopper Nervous System

16. Respiratory and Circulatory Systems • The respiratory system is responsible for exchanging oxygen and carbon dioxide between the body and the environment. • Gills • Lungs • The circulatory system transports gases, nutrients, and other substances within the body.

17. Circulatory System • Open circulatory system • a heart pumps fluid containing oxygen and nutrients through vessels into the body cavity. • The fluid provides oxygen and nutrients as it washes across the tissues. • Closed circulatory system • the blood is pumped through the body within vessels • is never in direct contact with the body's tissues.

18. Open and Closed Circulatory Systems

19. Reproduction • Asexual reproduction occurs when an individual produces exact copies of itself and gametes are not exchanged. • Budding • Parthenogenesis • Fragmentation • Sexual reproduction, a new individual is formed by the union of a male and female gametes. • Some species can reproduce either asexually or sexually.