Ch 33: Campbell Biology Chapter 33: An Introduction to Invertebrates
About This Chapter
How It Works:
- Identify the lessons in the Campbell Biology Introduction to Invertebrates chapter with which you need help.
- Find the corresponding video lessons with this companion course chapter.
- Watch fun videos that cover the invertebrates topics you need to learn or review.
- Complete the quizzes to test your understanding.
- If you need additional help, rewatch the videos until you've mastered the material or submit a question for one of our instructors.
Students will learn:
- Traits of Parazoans
- Types of Cnidarians
- Kinds of flatworms and roundworms
- Types of mollusks
- Traits of annelids
- Behaviors and characteristics of insects
- Characteristics of echinoderms
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1. Parazoa: Definition and Characteristics
Parazoans are sponges of various sizes, shapes, and colors that lack specialized tissue and are classified as animals. Learn about the definition, characteristics, and overall composition of parazoa.

2. Cnidarians: Types & Examples
Cnidarians are a group of invertebrate animals like jellyfish, corals, and sea anemones. Discover Cnidarian's body structure, Cnidarians types, examples of Cnidarians like anthozoa, hydrozoa, scyphozoa, and cubozoa.

3. Flatworms: Types & Structure
Flatworms are mostly parasitic organisms that cause harm to their hosts through sickness and disease. Explore the types, body structure, and systems of flatworms, and learn about Phylum Platyhelminthes, flukes, tapeworms, and planarians.

4. What are Roundworms? - Types, Examples & Characteristics
A roundworm, also known as a nematode, is a very small worm that lives in the intestines of people, pigs, and other animals. Discover the physical characteristics and taxonomic classification of roundworms as well as examples of roundworms that infect humans and how these infections are treated.

5. Mollusks: Characteristics & Types
Mollusks are invertebrates that have soft and flexible bodies and are usually encased in shells. Discover the definition and characteristics of mollusks, and explore the three main types: gastropods, bivalves, and cephalopods.

6. Annelids: Types & Structure
Annelids are worms with segmented bodies. Annelids are divided into three main classes. A brief description and example of each class will be provided in this lesson.

7. Echinoderms: Traits, Types & Roles
Echinoderms are marine invertebrates that have spiny skin and usually have a star, spherical, or elongated shape. Learn about the definition and examples of echinoderms, and explore their traits, types, and roles.
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Other Chapters
Other chapters within the Campbell Biology: Online Textbook Help course
- Campbell Biology Chapter 1: The Themes of Biology, and Scientific Inquiry
- Campbell Biology Chapter 2: The Chemical Context of Life
- Campbell Biology Chapter 3: Water and Life
- Campbell Biology Chapter 4: Carbon and the Molecular Diversity of Life
- Campbell Biology Chapter 5: The Structure and Function of Large Biological Molecules
- Campbell Biology Chapter 6: A Tour of the Cell
- Campbell Biology Chapter 7: Membrane Structure and Function
- Campbell Biology Chapter 8: An Introduction to Metabolism
- Campbell Biology Chapter 9: Cellular Respiration and Fermentation
- Campbell Biology Chapter 10: Photosynthesis
- Campbell Biology Chapter 11: Cell Communication
- Campbell Biology Chapter 12: The Cell Cycle
- Campbell Biology Chapter 13: Meiosis and Sexual Life Cycles
- Campbell Biology Chapter 14: Mendel and the Gene Idea
- Campbell Biology Chapter 15: The Chromosomal Basis of Inheritance
- Campbell Biology Chapter 16: The Molecular Basis of Inheritance
- Campbell Biology Chapter 17: Gene Expression: From Gene to Protein
- Campbell Biology Chapter 18: Regulation of Gene Expression
- Campbell Biology Chapter 19: Viruses
- Campbell Biology Chapter 20: DNA Tools and Biotechnology
- Campbell Biology Chapter 21: Genomes and Their Evolution
- Campbell Biology Chapter 22: Descent With Modification: A Darwinian View of Life
- Campbell Biology Chapter 23: The Evolution of Populations
- Campbell Biology Chapter 24: The Origin of Species
- Campbell Biology Chapter 25: The History of Life on Earth
- Campbell Biology Chapter 26: Phylogeny and the Tree of Life
- Campbell Biology Chapter 27: Bacteria and Archaea
- Campbell Biology Chapter 28: Protists
- Campbell Biology Chapter 29: Plant Diversity I
- Campbell Biology Chapter 30: Plant Diversity II
- Campbell Biology Chapter 31: Fungi
- Campbell Biology Chapter 32: An Overview of Animal Diversity
- Campbell Biology Chapter 34: The Origin of Evolution of Vertebrates
- Campbell Biology Chapter 35: Plant Structure, Growth, and Development
- Campbell Biology Chapter 36: Resource Acquisition and Transport in Vascular Plants
- Campbell Biology Chapter 37: Soil and Plant Nutrition
- Campbell Biology Chapter 38: Angiosperm Reproduction and Biotechnology
- Campbell Biology Chapter 39: Plant Responses to Internal and External Signals
- Campbell Biology Chapter 40: Basic Principles of Animal Form and Function
- Campbell Biology Chapter 41: Animal Nutrition
- Campbell Biology Chapter 42: Circulation and Gas Exchange
- Campbell Biology Chapter 43: The Immune System
- Campbell Biology Chapter 44: Osmoregulation and Excretion
- Campbell Biology Chapter 45: Hormones and the Endocrine System
- Campbell Biology Chapter 46: Animal Reproduction
- Campbell Biology Chapter 47: Animal Development
- Campbell Biology Chapter 48: Neurons, Synapses, and Signaling
- Campbell Biology Chapter 49: Nervous Systems
- Campbell Biology Chapter 50: Sensory and Motor Mechanisms
- Campbell Biology Chapter 51: Animal Behavior
- Campbell Biology Chapter 52: An Introduction to the Ecology of the Biosphere
- Campbell Biology Chapter 53: Population Ecology
- Campbell Biology Chapter 54: Community Ecology
- Campbell Biology Chapter 55: Ecosystems and Restoration Ecology
- Campbell Biology Chapter 56: Conservation Biology and Global Change