1. Section 2: Animal Body Systems

2. 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?

3. Support Skeleton hydrostatic skeleton exoskeleton
provides framework and support
vital to movement
hydrostatic skeleton
water-filled cavity that is under pressure
soft-bodied invertebrates
jellyfish
exoskeleton
rigid external skeleton that encases the body of an animal.
Insects, clams, and crabs

4. Support, continued endoskeleton
internal skeleton made of bone and cartilage.
Humans and other vertebrates

5. Visual Concept: Comparing Exoskeletons and Endoskeletons

6. Digestive and Excretory Systems
digestive system responsible for
Extracts energy and nutrients from an animal's food
excretory system
removes waste products from the animal's body

7. Digestive and Excretory Systems, continued
Digestive System
A gastrovascular cavity
Only one digestive cavity
no specialized digestive cells.
The hydra has a gastrovascular cavity.
Digestive tracts allow for specialization and more efficient digestion.

8. Digestive and Excretory Systems, continued
Excretion
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. Some convert ammonia to less toxic chemicals before passing them out of the body.

9. Nervous System nervous system
carries information about the environment
coordinates responses and behaviors
Not all animals have a complex nervous system, and some do not have a brain to coordinate the nervous system.

10. Nervous System, continued
Simple Nervous Systems
All animals except sponges have nerve cells.
In the simplest arrangement of nerves, called a nerve net, nerve cells do not coordinate actions efficiently.
Jellyfish and hydras have a nerve net.

11. Hydra Nervous System

12. Nervous System, continued
Simple Nervous Systems, continued
Many animals have clusters of nerve cells called ganglia that can coordinate responses.
Flatworms have large more-complex ganglia, similar to a brain.

13. Flatworm Nervous System

14. Nervous System, continued
Complex Nervous Systems
More-complex invertebrates have a true brain with sensory structures, such as eyes, associated with it.
Vertebrates
relatively large brain
many species have special sensory systems
makes these animals better at catching food
avoiding predators

15. Respiratory and Circulatory Systems
respiratory system
exchanges oxygen and carbon dioxide between the body and the environment
circulatory system
transports gases, nutrients, and other substances within the body

16. Respiratory and Circulatory Systems, continued
Respiratory System
Most animals have specialized respiratory systems.
Aquatic animals respire by using thin projections of tissue called gills.
A variety of respiratory organs, including lungs, have evolved in terrestrial animals.

17. Respiratory and Circulatory Systems, continued
In an 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.
In a closed circulatory system, the blood is pumped through the body within vessels and is never in direct contact with the body's tissues.

18. Open and Closed Circulatory Systems

19. Visual Concept: Comparing Open and Closed Circulatory Systems

20. Reproduction
Asexual reproduction occurs when an individual produces exact copies of itself and does not mix its genes with those of another.
Sea stars and some salamanders and fishes reproduce asexually.

21. Reproduction, continued
In sexual reproduction, a new individual is formed by the union of a male and female gamete.
Some species can reproduce either asexually or sexually.
Coral colonies grow larger through asexual reproduction, but new colonies are formed through sexual reproduction.

22. Summary
An animal's skeleton provides a framework that supports its body and is vital to animal movement.
The digestive system extracts energy and nutrients from an animal's food, while the excretory system removes waste products from the animal's body.
The nervous system carries information about the environment through the body and coordinates responses and behaviors.

23. Summary, continued
The respiratory system is responsible for exchanging oxygen and carbon dioxide between the body and the environment. The circulatory system transports gases, nutrients, and other substances within the body.
The two types of reproduction in animals are asexual and sexual.