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Chapter 18: From Sponges to Invertebrate Chordates

Difficulty Level: At Grade Created by: CK-12
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(Opening image copyright Mikhail Melnikov, 2010. Used under license from Shutterstock.com.)

From Sponges to Invertebrate Chordates


Lesson 18.1: Sponges, Cnidarians, Flatworms, and Roundworms

18.1.1 Sponges

  • Structure and Function of Sponges
  • Sponge Reproduction
  • Ecology of Sponges

18.1.2 Cnidarians

  • Structure and Function of Cnidarians
  • Cnidarian Reproduction
  • Ecology of Cnidarians
  • KQED: Amazing Jellies

18.1.3 Flatworms

  • Structure and Function of Flatworms
  • Flatworm Reproduction
  • Ecology of Flatworms

18.1.4 Roundworms

  • Structure and Function of Roundworms
  • Roundworm Reproduction
  • Ecology of Roundworms

Lesson 18.2: Mollusks and Annelids

18.2.1 Mollusks

  • Structure and Function of Mollusks
  • Mollusk Reproduction
  • Ecology of Mollusks
  • KQED: Cool Critters: Dwarf Cuttlefish
  • KQED: The Fierce Humboldt Squid
  • Where's the Octopus?

18.2.2 Annelids

  • Structure and Function of Annelids
  • Annelid Reproduction
  • Ecology of Annelids

Lesson 18.3: Arthropods and Insects

18.3.1 Arthropods

  • Structure and Function of Arthropods
    • Underwater Spiders
  • Arthropod Reproduction
  • Evolution of Arthropods
  • Classification of Arthropods

18.3.2 Insects

  • Structure and Function of Insects
  • Insect Flight
  • Insect Reproduction
  • Insect Behavior
  • KQED: Ants: The Invisible Majority
  • KQED: Landbugs: A Population of Millions
  • Insects and Humans
  • KQED: Better Bees: Super Bee and Wild Bee

Lesson 18.4: Echinoderms and Invertebrate Chordates

18.4.1 Echinoderms

  • Structure and Function of Echinoderms
  • Echinoderm Reproduction
  • Echinoderm Classification

18.4.2 Introduction to Chordates

  • Characteristics of Chordates
  • Classification of Chordates

18.4.3 Invertebrate Chordates

  • Tunicates
  • Lancelets

Pacing the Lessons

Use the Class Periods per Lesson table below as a guide for the time required to teach the lessons of this chapter.

Lesson Number of Class Periods
18.1 Sponges, Cnidarians, Flatworms, and Roundworms 2.0
18.2 Mollusks and Annelids 2.0
18.3 Arthropods and Insects 2.5
18.4 Echinoderms and Invertebrate Chordates 1.5
  • Class periods are assumed to be 60 minutes long.

Online Resources

See the following Web sites for appropriate laboratory activities:

1. Students can investigate whether different parts of planaria have the same ability to regenerate. (Lesson 18.1)

2. In this lab, students will observe and measure the physical traits and behaviors of freshwater snails. (Lesson 18.2)

3. This AP lab involves dissection of annelids. (Lesson 18.2)

4. This lab introduces students to variation in arthropod form and function. (Lesson 18.3)

5. In this lab, students will dissect a preserved grasshopper and examine its internal and external anatomy. (Lesson 18.3)

6. Students can examine the external anatomy of a preserved sea star and then dissect it and examine its internal anatomy. A dissecting microscope is required. (Lesson 18.4)

7. Students can observe prepared slides of tunicate larvae to identify the four defining chordate features. (Lesson 18.4)

These Web sites may also be helpful:

1. See the URL below for PowerPoint slide sets of invertebrates, including sponges, cnidarians, flatworms, and roundworms.

2. This is a PBS series with three episodes on simple invertebrates (“Origins,” “Life on the Move,” and “The First Hunter”). The Web site also has photos, articles, activities, and scientist profiles.

3. This University of Michigan Web site can be searched for photos of and articles about sponges, cnidarians, flatworms, and roundworms.

4. This 12-page PDF document provides a detailed summary of mollusks and annelids. It has excellent illustrations.

5. See these online biology chapters for more information on invertebrates.

6. At the URL below, you can find a concise compilation of useful information about the arthropod phylum. Materials include excellent labeled diagrams of arthropod body plans.

7. This brief echinoderm tutorial includes brilliant images of a variety of echinoderms.

Chapter Outline

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