Table of Contents

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

2. Section 1 Porifera Chapter 33 Body Plan of Sponges • 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.

3. Section 1 Porifera Chapter 33 Sponges Click below to watch the Visual Concept. Visual Concept

4. Section 1 Porifera Chapter 33 Structure of a Sponge

5. Section 1 Porifera Chapter 33 Parts of a Sponge Click below to watch the Visual Concept. Visual Concept

6. Section 1 Porifera Chapter 33 Collar Cells Click below to watch the Visual Concept. Visual Concept

7. 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.

8. Section 1 Porifera Chapter 33 Feeding Habits of Sponges Click below to watch the Visual Concept. Visual Concept

9. 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.

10. Section 1 Porifera Chapter 33 Sexual Reproduction in Sponges

11. Section 1 Porifera Chapter 33 Reproduction in Sponges Click below to watch the Visual Concept. Visual Concept

12. Section 1 Porifera Chapter 33 Gemmules Click below to watch the Visual Concept. Visual Concept

13. Section 2 Cnidaria and Ctenophora Chapter 33 • Section 33.2 Cnidarian and Ctenophora

14. 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.

15. 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.

16. Section 2 Cnidaria and Ctenophora Chapter 33 Cnidocyte Click below to watch the Visual Concept. Visual Concept

17. Section 2 Cnidaria and Ctenophora Chapter 33 Characteristics of Cnidarians Click below to watch the Visual Concept. Visual Concept

18. 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.

19. Section 2 Cnidaria and Ctenophora Chapter 33 Types of Cnidarians Click below to watch the Visual Concept. Visual Concept

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

21. Section 2 Cnidaria and Ctenophora Chapter 33 Movement of Hydra Click below to watch the Visual Concept. Visual Concept

22. Section 2 Cnidaria and Ctenophora Chapter 33 Reproduction in Hydras Click below to watch the Visual Concept. Visual Concept

23. Section 2 Cnidaria and Ctenophora Chapter 33 Reproduction in Aurelia

24. Section 2 Cnidaria and Ctenophora Chapter 33 Reproduction in Jellyfish Click below to watch the Visual Concept. Visual Concept

25. Section 2 Cnidaria and Ctenophora Chapter 33 Comparing Medusa and Polyp Bodies Click below to watch the Visual Concept. Visual Concept

26. Section 2 Cnidaria and Ctenophora Chapter 33 Coral Reefs

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

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

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

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

31. 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.