Ch 22: Introduction to Invertebrates

About This Chapter

Watch video lessons and learn about the unique features of invertebrates, such as the ones that might be living in or around your house! These easy-to-follow lessons are just a portion of our online study guide and video collection.

Introduction to Vertebrates - Chapter Summary and Learning Objectives

In this high school biology course, you'll learn how to identify and characterize invertebrates, one of the two major groups found in the animal kingdom. Invertebrates represent a diverse assortment of species, and you've probably noticed them at the beach, around the house or in your garden, including starfish, spiders and worms.

What sets these multi-cellular creatures apart from vertebrates is the absence of a backbone. Invertebrates also lack cell walls and are unable to make their own food. Through the videos in this chapter, you'll be introduced to some common types of invertebrates and find out how they are classified.

When you've finished watching the lessons and taking the online self-assessments, you should be able to identify and describe the following:

  • Parazoa or animals without tissues and organs, such as sponges
  • Radiata or radially symmetric animals, like jellyfish and sea stars
  • Protostomes, such as earthworms and squid
  • Deuterostomes, like sea cucumbers and sea urchins

Parazoa: Definition and CharacteristicsDefine and discuss the properties of parazoa.
Radiata: Definition and CharacteristicsDefine and discuss the properties of radiata.
Protostomes: Definition and CharacteristicsDefine and discuss the properties of protostomes.
Deuterostomes: Definition and CharacteristicsDefine and discuss the properties of deuterostomes.

5 Lessons in Chapter 22: Introduction to Invertebrates
Test your knowledge with a 30-question chapter practice test
Animal Body Plans: Classifications and Features

1. Animal Body Plans: Classifications and Features

The Animal Kingdom is diverse and complex. How do we make sense of it all? Scientists use body plans to classify and organize the animals of Earth, making it much easier to differentiate between them.

Parazoa: Definition and Characteristics

2. Parazoa: Definition and Characteristics

The sub-kingdom Parazoa is a special group of animals that are unlike any other. In this video lesson, you'll learn about the characteristics of Parazoans and identify what makes them a unique section of the Animal Kingdom.

Radiata: Definition and Characteristics

3. Radiata: Definition and Characteristics

The super-phylum Radiata describes a unique and interesting group of animals. In this video lesson you'll identify various animals that belong in this classification as well as describe the characteristics that make them so identifiable.

Protostomes: Definition and Characteristics

4. Protostomes: Definition and Characteristics

Though you may not be able to tell just by looking at them, protostomes are an evolutionarily related group based on shared characteristics of their body plans. In this lesson, you will identify these characteristics, as well as see examples of the variety of animals this group encompasses.

Deuterostomes: Definition and Characteristics

5. Deuterostomes: Definition and Characteristics

Deuterostomes, like tunicates and urchins, are amazing creatures that are classified together because they share aspects of their evolutionary pasts. In this lesson, you'll identify these characteristics and see what makes this group of animals unique.

Chapter Practice Exam
Test your knowledge of this chapter with a 30 question practice chapter exam.
Not Taken
Practice Final Exam
Test your knowledge of the entire course with a 50 question practice final exam.
Not Taken

Earning College Credit

Did you know… We have over 200 college courses that prepare you to earn credit by exam that is accepted by over 1,500 colleges and universities. You can test out of the first two years of college and save thousands off your degree. Anyone can earn credit-by-exam regardless of age or education level.

To learn more, visit our Earning Credit Page

Transferring credit to the school of your choice

Not sure what college you want to attend yet? has thousands of articles about every imaginable degree, area of study and career path that can help you find the school that's right for you.