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Invertebrates: Sponges and Cnidarians 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 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 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 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!!! The Anatomy of a Sponge Section 26-2 Osculum Central cavity Pores Water flow Choanocyte Spicule Pore cell Pore Epidermal cell Archaeocyte 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 Cnidarian Body Forms Polyp: body with tentacles hanging upward Ex: hydra, sea anemone Medusa: body with tentacles hanging downward Ex: jellyfish 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 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? Cnidarian Structures: Label the hydra on your left page 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 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 Quiz 1. 2. 3. 4. 5. 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