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Chapter 32 Notes

by: Anna Shulpina

Chapter 32 Notes BIOL 1442 - 003

Anna Shulpina
Austin Community College
GPA 3.03
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About this Document

Notes from textbook and professor's powerpoints Simplified, more like review notes Covers all major topics
Walter Schargel
Class Notes
Biology, BiologyChapter32





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This 6 page Class Notes was uploaded by Anna Shulpina on Tuesday January 26, 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 10 views. For similar materials see EVOLUTION AND ECOLOGY in Biology at University of Texas at Arlington.


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Date Created: 01/26/16
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 Zygoterapid 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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