Introduction to Animal Diversity
Introduction to Animal Diversity BSC 116
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This 4 page Class Notes was uploaded by Paola Araque on Tuesday February 23, 2016. The Class Notes belongs to BSC 116 at University of Alabama - Tuscaloosa taught by Dr. Cherry in Spring 2016. Since its upload, it has received 21 views. For similar materials see Principles Biology II in Art at University of Alabama - Tuscaloosa.
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Date Created: 02/23/16
Introduction to Animal Diversity and Early Animal Evolution ❖ NonTerrestrial Arthropod Invertebrates ➢ Crustacea and other arthropods ➢ Mollusca ➢ Platyhelminthes ➢ Nematoda ➢ Annelida ➢ Cnidaria ➢ +27 more phyla ❖ What is an animal? ➢ multicellular eukaryotic heterotrophs ➢ don’t have a cell wall, their supportcollagen ➢ animals ingest their food and use enzymes to digest it ➢ have muscle and nerve tissue ❖ Characteristic early development of animals ➢ Sexual Reproduction: diploid adults→haploid gametes ➢ small flagellated sperm, and large eggs ➢ After Fertilization: ■ zygote→blastula→gastrula ■ zygote undergoes 3 rounds of division→8 cell embryo ■ hollow balls of cell surrounding the blastocoel cavity ■ invagination of embryo→endoderm, ectoderm, and archenteron “pouch” with the blastopore ❖ Different Developmental Patterns ➢ direct development: offspring looks like a smaller version of the parent ■ mammals and some insects ➢ indirect development: the young offspring (larvae) is different than the adults ■ butterflies, mollusks, some insects ❖ Where did animals come from? ➢ Closest relative: colonial choanoflagellate protists ❖ Paleozoic: began about 542 MYA ➢ Permian (ends with Permian extinction) ➢ Carboniferous (land invasion by vertebrates 360 MYA b/w carb. and devonian) ➢ Devonian ➢ Silurian ➢ Ordovician (1st land invasion [plants] 460 MYA) ➢ Cambrian (mostly marine) ■ rapid increase in extant animal phyla ■ decline in Edicarans ❖ Proterozoic Eon ➢ Edicaran ❖ Archean Eon ❖ Cenozoic: began about 65 MYA; diversification of large mammals (humans). ➢ Quaternary ➢ Neogene ➢ Paleogene ❖ Mesozoic: began 542 MYA; animals “bounce back” after Permian extinction.Ends with Cretaceous Extinction (end of dinosaurs) ➢ Cretaceous ➢ Jurassic ➢ Triassic ❖ Animals have Conserved “Body Plans” ➢ BROAD Patterns of Development ➢ Hox genes control animal development for all but the simplest animals ■ Regulate transcription of other genes ■ Conserved across animal taxa ■ Underwent series of duplications ■ Flexible enough to permit diversity ❖ Symmetry: more advanced animals bilaterally symmetrical ➢ Asymmetry (sponges) ➢ Radial Symmetry (sea anemone, jellyfish) ➢ Bilateral Symmetry (most animals) ❖ Gastrulation leads to embryonic tissues ➢ Asymmetrical animals (sponges) lack tissues; cells can dedifferentiate into other cell types ➢ Radial and bilateral animals undergo gastrulation: ■ Archenteron: embryonic gut ■ Endoderm: tissue lining gut ■ Ectoderm: outer layers of cells, nervous system ■ Radial Diploblaststwo tissues (endo and ectoderm) ■ Bilateral Triploblastthree tissues (+ mesoderm) ❖ Body Cavities of triploblasanimals: ➢ consider the coelom (fluidfilled body cavity) ➢ coelomates: lined with mesoderm ■ has a tissue layer lining the coleum and suspending internal organs (from mesoderm) ➢ psuedocoelomates: not completely lined with mesoderm; includes tissue derived from endoderm ■ has a muscle layer (from mesoderm) ➢ acoelomates: lack a body cavity ■ has a wall of digestive cavity (from endoderm) ■ has tissue filled region (from mesoderm) ❖ Coelomates c an be protostomes or deuterostomes ➢ Cleavage: ■ inprotostome development the eight cell stagspiral and determinate, and the cell fate is set early in development ■ indeuterostome development the eight cell stagradial and intermediate, the cell fate is NOT set early; each cell can develop into a complete embryo ➢ Coelom Formation: ■ inprotostome development the eight cell stage solid masses of mesoderm split and form coelom ■ indeuterostome development the eight cell stage folds of archenteron from coleum ➢ Fate of the Blastopore: ■ inprotostome development the eight cell stagemouth develops from blastopore ■ indeuterostome the eight cell stage anus develops from blastopore ❖ Animal Relationships: shaped by new morphological and molecular data ➢ All animals share a common ancestor ➢ sponges are a basal animal ➢ eumetazoa is a clade of animals with true tissues ➢ most animals belong to the Bilateria clade ➢ 3 major clades of Bilateria: ■ deuterstomia ■ lophotrochozoa ■ ecdysozoa ❖ Major Animal Groups: ➢ 5 Major Groups of animal phyla ■ porifera: sponges → no tissues or symmetry ■ cnidaria: jellyfish, sea anemone, coral ■ →diploblastic, radial symmetry ■ lophotrochozoa: flatworms, mollusks, segmented worms ■ → triploblastic, bilateral symmetry ■ ecdysozoa: arthropods, nematodes → “ “ ■ deuterostomia: echinoderms, chordate→ “ “ ❖ Phylum Porifera: Sponges ➢ body: water flows in through holes (ostia) and ouosculum ■ filter feeders ➢ inner and outer layer of cells separated by gelatimesohyl ➢ skeleton of firmspongin, or hard calcium carbonate or silica ➢ most are hermaphrodites ➢ cross fertilization when gametes released to water column ❖ Developmental biology and animal body plans ➢ asymmetry, radial, bilateral ➢ endo, ecto, mesoderm ➢ coelomates, psuedocoelomates, acoelomates