1. Chapter 33 Table of Contents Section 1 Porifera
Sponges, Cnidarians, and Ctenophores
Chapter 33
Table of Contents
Section 1 Porifera
Section 2 Cnidaria and Ctenophora

2. Chapter 33 Objectives Describe the basic body plan of a sponge.
Section 1 Porifera
Chapter 33
Objectives
Describe the basic body plan of a sponge.
Describe the process of filter feeding in sponges.
Contrast the processes of sexual and asexual reproduction in sponges.

3. Chapter 33 Body Plan of Sponges Section 1 Porifera
The phylum Porifera is made up of sponges.
Sponges are sessile invertebrates that have no true tissues or organs. The simplest sponges are shaped like hollow cylinders.
The body wall of a sponge is composed of two layers of cells that are separated by a jellylike substance called mesohyl.
Choanocytes in the interior layer draw water through the ostia that penetrate the body wall. The water leaves through the osculum.
The body is supported by a skeleton made of spongin, spicules, or both.

4. Chapter 33 Sponges Section 1 Porifera
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5. Section 1 Porifera
Chapter 33
Structure of a Sponge

6. Chapter 33 Parts of a Sponge Section 1 Porifera
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7. Chapter 33 Collar Cells Section 1 Porifera
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8. Feeding and Digestion in Sponges
Section 1 Porifera
Chapter 33
Feeding and Digestion in Sponges
Sponges feed by filtering small organisms and organic matter out of the water that passes through their body. This is called filter feeding.
Nutrients are distributed through the body by amoebocytes, cells which crawl about within the body wall.

9. Feeding Habits of Sponges
Section 1 Porifera
Chapter 33
Feeding Habits of Sponges
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10. Reproduction in Sponges
Section 1 Porifera
Chapter 33
Reproduction in Sponges
Sponges can reproduce both asexually and sexually.
They reproduce asexually through:
producing buds or gemmules
regeneration of missing parts
They reproduce sexually through the joining of egg and sperm.
Most sponges are hermaphrodites, which can produce both eggs and sperm.

11. Sexual Reproduction in Sponges
Section 1 Porifera
Chapter 33
Sexual Reproduction in Sponges

12. Reproduction in Sponges
Section 1 Porifera
Chapter 33
Reproduction in Sponges
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13. Chapter 33 Gemmules Section 1 Porifera
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14. Chapter 33 Objectives Describe the basic body plan of a cnidarian.
Section 2 Cnidaria and Ctenophora
Chapter 33
Objectives
Describe the basic body plan of a cnidarian.
Summarize how cnidarians feed.
Describe the nervous system of cnidarians.
Identify and give examples of the four classes of cnidarians.
Describe the common characteristics of ctenophores.

15. Body Plan of Cnidarians
Section 2 Cnidaria and Ctenophora
Chapter 33
Body Plan of Cnidarians
Animals in the phylum Cnidaria are radially symmetrical aquatic invertebrates that are more complex than the sponges. They have tissues and a few simple organs.
The cnidairan body is either a sessile polyp or a swimming medusa. Some cnidarians alternate between both types during their life cycles.
The body of a cnidarian consists of two cell layers:
an outer epidermis
an inner gastrodermis
The layers are separated by the mesoglea.
The gastrovascular cavity has a single opening (the mouth) surrounded by tentacles.

16. Feeding and Defense in Cnidarians
Section 2 Cnidaria and Ctenophora
Chapter 33
Feeding and Defense in Cnidarians
Cnidarians have cells called cnidocytes.
Each cnidocyte contains a nematocyst.
When a cnidocyte is stimulated, its nematocyst ejects a filament that can paralyze or ensnare prey.
Nervous System in Cnidarians
The cnidarian nervous system is a diffuse web of interconnected nerve cells called a nerve net.

17. Classification of Cnidarians
Section 2 Cnidaria and Ctenophora
Chapter 33
Classification of Cnidarians
The four classes of cnidarians are:
Class Hydrozoa
This class includes Obelia, man-o-war, and the hydra.
Hydrozoans may live as polyps, medusae, or mixed colonies.
Class Cubozoa
This class includes box jellies.
Cubozoans spend most of their lives as medusae.
Class Scyphozoa
This class includes jellyfish.
Scyphozoans spend most of their lives as medusae.
Class Anthozoa
This class includes sea anemones and corals.
Anthozoans live only as polyps.

18. Reproduction in Obelia
Section 2 Cnidaria and Ctenophora
Chapter 33
Reproduction in Obelia

19. Chapter 33 Movement of Hydra Section 2 Cnidaria and Ctenophora
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20. Reproduction in Hydras
Section 2 Cnidaria and Ctenophora
Chapter 33
Reproduction in Hydras
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21. Reproduction in Aurelia
Section 2 Cnidaria and Ctenophora
Chapter 33
Reproduction in Aurelia

22. Reproduction in Jellyfish
Section 2 Cnidaria and Ctenophora
Chapter 33
Reproduction in Jellyfish
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23. Comparing Medusa and Polyp Bodies
Section 2 Cnidaria and Ctenophora
Chapter 33
Comparing Medusa and Polyp Bodies
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24. Section 2 Cnidaria and Ctenophora
Chapter 33
Coral Reefs

25. Chapter 33 Phylum Ctenophora
Section 2 Cnidaria and Ctenophora
Chapter 33
Phylum Ctenophora
Animals in the phylum Ctenophora are known as ctenophores and often called comb jellies.
Ctenophores move through the water by beating the cilia that occur in eight rows on the outside of their body.
Ctenophores capture prey with a sticky substance secreted by their colloblasts.
An apical organ at one end of the body enables ctenophores to sense their orientation in the water.
Most ctenophores are hermaphroditic.
Many ctenophores have bioluminescence.

26. Two Cnidarian Body Forms
Section 2 Cnidaria and Ctenophora
Chapter 33
Two Cnidarian Body Forms

27. Section 2 Cnidaria and Ctenophora
Chapter 33
Cnidarian Body Plan

28. Exploration of a Cnidarian
Section 2 Cnidaria and Ctenophora
Chapter 33
Exploration of a Cnidarian

29. Development of Cnidarian Embryo
Section 2 Cnidaria and Ctenophora
Chapter 33
Development of Cnidarian Embryo

30. Characteristics of Cnidarians
Section 2 Cnidaria and Ctenophora
Chapter 33
Characteristics of Cnidarians
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31. Chapter 33 Cnidocyte Section 2 Cnidaria and Ctenophora
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32. Chapter 33 Types of Cnidarians Section 2 Cnidaria and Ctenophora
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