Chapter 32 Biology notes
Chapter 32 Biology notes BIOL 1442 - 003
Austin Community College
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This 6 page Class Notes was uploaded by Anna Shulpina on Thursday March 31, 2016. The Class Notes belongs to BIOL 1442 - 003 at University of Texas at Arlington taught by Walter Schargel in Spring 2016. Since its upload, it has received 9 views. For similar materials see EVOLUTION AND ECOLOGY in Biology at University of Texas at Arlington.
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Date Created: 03/31/16
Biology Chapter 32 (An Overview of Animal Diversity) notes Concept 32. 1: Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layers. Nutritional mode: Animals are heterotrophs that INGEST their food and use ENZYMES to digest it. Cell Structure and Specialization: NO cell walls. Use the STRUCTURAL PROTEIN collagen (on outside of cell membrane) for structural support Most have Nervous and muscle tissues: important characteristic, move the body and conduct nerve impulses. Reproduction and Development: most: Sexual reproduction; DIPLOID=DOMINANT Haploid stage: Meiotic division= sperm + egg cells production Small, flagellated sperm+ Large, nonmoving egg= diploid zygote Zygoterapid cell division (cleavage) blastula forms (hollow ball) Blastula- gastrulation gastrula with different layers of embryonic tissues Most animals have a life cycle with one LARVAL STAGE Larva (sexually immature, morphologically different from adult, eats different food, may even have different habitat) metamorphosis- juvenile (looks like an adult, but not yet sexually mature) Regulatory genes have homeoboxes Hox genes( developmental genes) regulate the development of body form SPONGES= NO HOX GENES; but have HOMEOBOXES that affect their shape Concept 32.2: The history of animals spans more than half a billion years. 1.3 million + species have been named but more exist. Common ancestor of ALL living animals: 700~770 million years ago Group of protists called choanoflagellates: closest living relatives to animals Neoproterozoic Era (1 Billion – 542 Million years ago) - Ediacarn biota (comes from Ediacara Hills of Australia): early members of animal fossil record - some sponges, others related to cnidarians, others difficult to classify - rocks: remains of early animals - ~560 million years ago Paleozoic Era (542-251 Million years ago) - Cambrian Explosion (535 to 525 million years ago): earliest fossil appearance of major groups of living animals - Found oldest fossils of first arthropods, chordates, echinoderms: look different from living animals - Cambrian explosion: mostly bilaterians (bilaterally symmetric form, complete digestive tract, one-way digestive system) - Hypotheses about decline of Ediacaran biota and cause of Cambrian explosion: 1) new predator-prey relationships: predators could find prey easier because of new adaptations; prey acquired better defenses (protective shells)natural selection some groups arise, others decline: 2) a rise in atmospheric oxygen: preceded Cambrian explosion: oxygen increase in metabolic rates, larger body sizes easier to survive, others dying. 3) the evolution of Hox gene complex: new body forms emerge - After Cambrian explosion: Ordovician, Silurian, Devonian periods: animal diversity increases, with mass extinctions - Fish top predators of marine food web - Animals start to make impact 450 million years ago - Arthropods adapt to land (centipedes and millipedes) - Vertebrates move to land 365 million years ago - Today’s survivors: amphibians + amniotes Mesozoic Era (251- 65.5 million years ago) - Emergence of Coral reefs - Some reptiles return to water - Land: origin of wings + flight - Dominant terrestrial vertebrates: Dinosaurs - The first mammals (tiny insect-eaters) came about - Diversification of flowering plants and insects Cenozoic Era (65.5 Million years ago to the Present) - After mass extinctions of terrestrial+ marine animals (large, nonflying dinosaurs and marine reptiles)= Cenozoic era occurs - Mammals growing larger and inhabit ecological niches. - Climate cools primates adapted to open woodlands & savannas (our ancestors) Concept 32.3. Animals can be categorized by “body plans” Symmetry Body plan: Morphological and Developmental traits that make a whole Key step in molecular control of gastrulation: didn’t change for 500 million years + Two symmetries: RADIAL and BILATERAL SPONGES= NO SYMMETRY Radial symmetry Bilateral symmetry No front and back/left and right Two-sided symmetry Dorsal (top); ventral (bottom); right & left side; anterior (front); posterior (back) Arthropods+ mammals: Central nervous system (brain) at anterior end: called CEPHALIZATION Sessile or planktonic Move from place to place: central nervous system allows to crawl, burrow, fly, or swim Tissues Body plans vary depending on tissue organization In development: THREE germ layers give rise to tissues and organs Ectoderm (OUTER): layer that covers embryo’s surface (rise to central nervous system in some); Endoderm (INNER): lines the developing digestive tube (archenteron) (rise to the lining of digestive tract, liver, lungs) Sponges: NO TRUE TISSUES Embryo becomes layered by GASTRULATION Diploblastic animals have ONLY ectoderm and endoderm (cnidarians (jellies+corals) and few others) Triploblastic animals: also have a mesoderm (between endoderm and ectoderm) (forms muscles, other organs) (all bilaterians (flatworms, arthropods, vertebrates, others)) Body Cavities Triploblastic animals have a BODY CAVITY: fluid filled space between digestive tract & outer body wall True body Cavity= Coelom (animals with coelom=coelomates), comes from MESODERM Pseudocoelom (animals with pseudocoelom= pseudocoelomates): comes from MESODERM + ENDODERM Triploblastic animals with NO BODY CAVITY= ACOELOMATES Functions of body cavity: 1) Fluid holds organs 2) Fluid acts like skeleton in earthworms 3) Allows organs to grow & move (heart beat+ intestines ripple) Protostome and Deuterostome Development Protostome Deuterostome Cleavage spiral + determinate Cleavage radial+indeterminate -indeterminate: each cell in cleavage can form into a complete embryo Splitting of solid masses of mesoderm forms Mesoderm buds from wall of archenteron to form COELOM COELOM Blastopore: forms during gastrulation connects Blastopore: forms during gastrulating connects archenteron to outside of gastrula archenteron to outside of gastrula Blastospore=MOUTH Blastopore=ANUS Concept 32.4: New views of animal phylogeny are emerging from molecular data THREE DOZEN animal phyla Porifera (basal) Ctenophora Cnidaria True tissues Acoela Deuterostomia Bilateral symmetry; three germ layers Lophotrochozoa Ecdysozoa Five important points: 1. All animals share a common ancestor: animals are monophyletic, clade Metazoa 2. Sponges are basal animals: base of both animal trees 3. Eumetazoa (“true animals”) is a clade of animals with true tissues: true tissues evolved in common ancestor; Ctenohora (comb jellies)+ cnidarian: diploblastic, radial symmetry 4. Most animal phyla belong to the clade Bilateria: bilateral symmetry+ three germ layers: shared derived characters. 5. Chordates and some other phyla belong to the clade Deuterostomia Bilaterians: THREE CLADES : 1) Deuterostomia, 2) Ecdysozoa, 3) Lophotrrochozoa 1) DEUTEROSTOMIA: hemichordates (acorn worms), echinoderms (sea stars and relatives), chordates 2) Ecdysozoa : ECDYSIS (shedding of exoskeleton by invertebrates) 3) Lophotrochozoa: SOME: LOPHOPHORE (feeding structure); OTHERS: TROCHOPHORE LARVA (development stage)
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