Biology Test 3
Chapter 23 Animals 1: Major Invertebrate Groups
23.1 old genes new drugs * Vertebrates – an animal that has a back bone * Mammals, birds, reptiles, amphibians, and fish * Invertebrates – an animal that does not have a back bone * More than 97% * Cone snails (genus Conus) found in warn nearshore waters of South Pacific, patterned shells, they are predators and produce venom. * Produce a pain killing drug call ziconotide (prialt), unlike morphine it is non addictive.
23.2 animal traits and trends * Animals – multicelled heterotrophy with unwalled cells. Most ingest food and are motile during at least part of the life cycle. * Evolution of Animal Body Plans * All animals are descended from a common multicelled ancestor * Ectoderm – outermost tissue layer of an animal embryo. * Endoderm – innermost tissue layer of an animal embryo. * Mesoderm – middle tissue layer of a three – layered animal embryo. * Most animal groups have organs derived from mesoderm * Radial symmetry – having parts arranged around a central axis, like spokes around a wheel * Radial animals have no front or back end. They attach to an underwater surface or drift along. Their food can arrive from any direction. * Bilateral symmetry – having paired structures so the right and left halves are mirror images * Bilateral animals typically have cephalization. * Move through the world head first and use their sensory structures on the head to seek out food and detect threats * Head ends have an opening for taking in food. * Cephalization – having a concentration of nerve and sensory cells at the head end. * Protostomes – lineage of bilateral animals in which the first opening on the embryo surface develops into a mouth * Deuterostomes – lineage of bilateral animals in which the second opening on the embryo surface develops into a mouth. * Pseudiciekin – unlined body cavity * Tape worm * Coelom – body cavity lined with tissue derived from mesoderm. * Segmentation – a division of a body into similar units repeated one after the other along main axis.
23.3 animal origins and early radiations * The colonial theory of animal’s origins says that the first animals evolved from a colonial protest. * Choanoflagellate – member of the protest group most closely related to animals * Placozoan – the simplest modern animal with an asymmetrical flat body, four types of cells, and a small genome. *
