Invertebrates: Sponges and Cnidarians

1. Invertebrates: Sponges and Cnidarians

2. Journal 2 • You are an expert taxonomist who has been given an unknown specimen to identify. You suspect that it is an animal. How could you prove your hypothesis? • Open your books to page 664

3. Sponges: • Phylum Porifera means- pore bearer • Simplest of all animals • Assymetrical animals that live in shallow waters • Sessile filter-feeders whose bodies have many pores • Acoelomates-no body cavity • Obtain oxygen by filtering water • Uses: cleaning, bathing, cosmetics • No nervous system or organ systems

4. Sponge Reproduction • Reproduce Asexually by budding: • Buds form from sides of parent sponge, bud break off and grow into new individual • can grow back missing parts (regeneration) • Reproduce sexually: • Hermaphrodites: produce both eggs and sperm • Gametes are released into water

5. Sponge Body Structures: • Osculum: large opening at the top of the sponge • Pore cells: openings to bring in water • Collar cells (choanocytes): line interior, have flagella to help filter water • Spicules: hard, supportive structures found in body of sponge LABEL THE SPONGE ON YOUR LEFT PAGE!!!

6. The Anatomy of a Sponge Section 26-2 Water flow Osculum Central cavity Choanocyte Pores Spicule Pore cell Pore Epidermal cell Archaeocyte

7. Cnidarians: • Phylum Cnidaria: means “stinging cell” • Marine • Radial symmetry • Have tentacles • Predators: capture and poison prey with stinging cells on tentacles (NEMATOCYST) • Acoelomates • Oxygen diffuses into body from water

8. Cnidarian Body Forms • Polyp: body with tentacles hanging upward • Ex: hydra, sea anemone • Medusa: body with tentacles hanging downward • Ex: jellyfish

9. Cnidarian Reproduction: • Asexually reproduce by budding • Sexually reproduce in medusa form only, sperm and eggs are released into water • Thousands of gametes are released at a time

10. Time to Think! Why do sponges and cnidarians release so many gametes into the water? The body plan of an animal relates to its complexity. What does that tell you about sponges and Cnidarians since they are both acoelomates?

11. Cnidarian Structures: • Basal disc: sticky end of polyp form which allows them to stay in one spot • One body opening (mouth) for food to enter and wastes to exit • Gastrovascular cavity: interior cavity where food is digested & nutrients are circulated around the body • Nerve net: net of nerves that allow impulses to travel around the body, senses the environment • Muscles: some muscles are present; allows for some movement Label the hydra on your left page

12. Three groups of cnidarians • Hydrozoans: colonies which appear to be one organism • Ex: portugese-man-of-war • Scyphorozoans: independent medusas • Ex: jellyfish, box jellies • Anthozoans: colonies of polyps • Ex: corals, sea anemones

13. Quiz • Sponges __ animals. a. are b. are not • Sponges can reproduce asexually by ___. a. budding b. regeneration c. both • Hydras have their tentacles pointing upwards. They are __. a. medusas b. nematocysts c. polyps • All cnidarians have ___ symmetry. a. bilateral b. radial c. no symmetry • Cnidarians poison their prey with stinging cells called ___. a. choanocytes b.nematocysts c. osculum