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Ch 26- Sponges and Cnidarians

Ch 26- Sponges and Cnidarians. What characteristics do all animals share? Members of kingdom Animalia , multicellular , eukaryotic heterotrophs , lack cell walls Invertebrates- animals that do not have a backbone 95% of all animal species Range in size from dust mites to giant squids

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Ch 26- Sponges and Cnidarians

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  1. Ch 26- Sponges and Cnidarians • What characteristics do all animals share? • Members of kingdom Animalia, multicellular, eukaryotic heterotrophs, lack cell walls • Invertebrates- animals that do not have a backbone • 95% of all animal species • Range in size from dust mites to giant squids • Vertebrates- animals that have a backbone • Fish, amphibians, reptiles, birds, mammals

  2. What essential functions do animals carry out? • Feeding, respiration, circulation, response, movement, and reproduction • What are the important trends in animal evolution? • High levels of cell specialization and internal body organization in complex animals • Bilateral body symmetry • Front end or head with sense organs • Body cavity

  3. Sponges • Why are sponges classified as animals? • Multicellular, heterotrophic, no cell walls, contain a few specialized cells • Phylum Porifera • Are sessile and filter feeders • Body plan • Asymmetrical, forms wall around large central cavity • Choanocytes- specialized cells that use flagella to move steady current of water through sponge • Osculum- large hole at top of sponge • Spicule- spike shaped structrure made of chalklike calcium carbonate • Archaeocytes- specialized cells that move around within the walls of sponge

  4. How do sponges carry out essential functions? • Movement of water throughout sponge • Characteristics of sponges • No true tissues or organs • Food digested by collar cells and nutrients are passed to rest of body • Produce toxins • Feed on bacteria, protozoans, unicellular algae • May reproduce either sexually or asexually • Internal fertilization • Gemmules- groups of archaeocytes surrounded by tough layer of spicules • Play an important role in the primary productivity of coral reefs

  5. Cnidarians • What is a cnidarian? • Soft-bodied, carnivorous animals with stinging tentacles arranged in circles around their mouths • Simplest animals to have body symmetry and specialized tissues • Cnidocyte- stinging cells, located along tentacles • Nematocyst- poison-filled, stinging structure that contains tightly coiled dart

  6. Form and Function in Cnidarians • Polyp-sessile and vase shaped-cylindrical • Medusa-swimming and bell shaped • Radially symmetrical • Most cnidarians reproduce both sexually and asexually

  7. Groups of Cnidarians • Jellfishes, hydras, sea anemones, corals • Scyphozoa-means cup animals • Sexual reproduction • Medusa dominant form of life cycle • Nematocysts-poison • Common jellyfish • Hydrozoa • Hydras are most common freshwater, lack a medusa stage • Sexual or asexually • Portuguese man-of-war • Anthozoa • Sea anemones • Sessile, only polyps • Coastal areas • Tentacles and feed on fish • Corals • Polyps in colonies • Calcium carbonate • Warm clear water • Coral reefs

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