Transcript Animals
Animals: The Invertebrates Chapter 23 Key Concepts: All animals are multicelled, aerobic heterotrophs Animals originated about 900 million years ago Comparisons of body plans of existing animals with fossil records reveal that there were several trends in the evolutions of certain lineages Key Concepts: Divergences gave rise to two major lineages: those of the mollusks, annelids, and arthropods and the other one to the echinoderms and chordates The arthropods, especially the insects, have been the most successful animal groups Evolutionary Tree Diagram Overview of the Animal Kingdom Animals Multicellular Heterotrophs Oxygen is required Sexual reproduction (some asexual) Motile - in part of life cycle Embryonic development Mitotic cell divisions in embryo Tissue layers • Ectoderm, Endoderm, Mesoderm Diversity in Body Plans Vertebrates Mammals birds, reptiles, amphibians, fishes Invertebrates No backbones Body symmetry & Cephalization ( sense in the head) Gut Body cavity Segmentation Examples of Body Symmetry Radial Live in water Bilateral Mirror image Type of Body Cavity in Animals Gut, body cavities, segmentation Type of Body Cavity in Animals Lined body cavity Sponges Success in Simplicity No symmetry, tissues, or organs Sponges Success in Simplicity A basket sponge releasing a cloud of sperm Tissues in a Jellyfish The sea nettle, a jellyfish (Chrysaora) Stages in Cnidarian Life Cycles Both polyp and medussa body forms Physalia Portuguese Man-of-War Flatworms: Turbellarians, Flukes & Tapeworms Nervous system in a Planarian Reproductive system in a Planarian Tapeworms Parasitic Scolex Proglottids Hermaphroditic Roundworms Most abundant multicelled animal Bilateral symmetry Cylindrical body Cuticle Complete digestive system Male and female Flukes Parasitic Sexual or asexual phases Two hosts Snail Human Life Cycle of Schistosoma japonicum A Sampling of Mollusks Mollusk Soft body Shell Mantle Fleshy foot Gastropods-snails Chitons Bivalves-clams Cephalopods-squid Evolutionary Experiments with Body Plans Radula is used to scrape food into the mouth Evolutionary Experiments with Body Plans Body Plan of a clam Evolutionary Experiments with Body Plans Body Plan of a cuttlefish, a cephalopod Annelids: Segments Galore Bilateral Segmented Earthworms Leeches Polychaetes Earthworm Body Plan Coelomic chambers A nephridium Earthworm Body Plan Portion of the closed circulatory system Part of the digestive system Earthworm Body Plan Part of the nervous system Arthropods: The Most Successful Organisms on Earth-Arthropods Over one million species Trilobites (extinct) Chelicerates Spiders Crustaceans Barnacles and crabs Uniramians Centipedes, millipedes, insects Adaptations of Insects and Other Arthropods Hardened exoskeleton Jointed appendages Fused and modified segments Respiratory structures Specialized Sensory Structures Division of labor A Look at Spiders Organization of a Spider Body A Look at Crustaceans Shrimps, lobsters, crabs, barnacles A Copepod A Lobster Life Cycle of a Crab Continuous molting A Look at Insect Diversity Head, thorax, abdomen Sensory antennae Mouthparts 3 pairs of legs 2 pairs of wings Malphigian tubules Waste disposal Life cycles A Look at Insect Diversity Examples of Appendages Grasshopper Fly Butterfly Mosquito Examples of Post-Embryonic Development Silverfish True bugs Fruit flies The Puzzling Echinoderms Echinoderms Sea star Body walls Spines, spicules Sea urchin Radial symmetry Sea cucumber Decentralized nervous system Brittle stars Water-vascular system The Puzzling Echinoderms Sea urchin Key Aspects of the Radial Body Plan of a Sea Star In Conclusion Animals are multicellular, aerobic heterotrophs that ingest or parasitize other organisms Animals range from structurally simple placozoans and sponges to vertebrates In Conclusion Almost all animals more complex than cnidarians show bilateral symmetry, form tissues, organs, and organ systems All mollusks have a fleshy soft body, and a mantle In Conclusion The annelids, have a segmented body, complex organs, and coelomic chambers Arthropods are the most successful of all groups in terms of diversity, numbers, distribution, defenses, and capacity to exploit food resources Echinoderms have spines, spicules, or plates in their body wall developed by M. Roig