Transcript Arthropods
Comparing Invertebrates QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. The First Multicellular Animals QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. • Fossils evidence from Ediacara Hills, Australia show some of the earliest and most primitive animals (575-543 mya). Altough these animals were bilateral and segmented, they were probably simple and with little internal specialization. Beginnings of Invertebrate Diversity (The Cambrian Explosion) QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Burgess Shale fossil evidence shows that animals became more diverse after the Cambrian period (544 mya). Some animals had evolved shells, skeletons, and other hard body parts - which were preserved as fossils. The Cambrian Explosion Video Clip: http://www.pbs.org/wgbh/evolution/library/03/4/l_034_02.html Invertebrate Phylogeny Invertebrate Cladogram Echinoderms Chordates Arthropods Annelids Mollusks Radial Symmetry Roundworms Flatworms Cnidarians Radial Symmetry Sponges Pseudocoelom Coelom Protostome Development Three Germ Layers; Bilateral Symmetry Tissues Multicellularity Single-celled ancestor Deuterostome Development Cladogram (shows evolutionary relationships) Evolutionary Trends • Specialized Cells, Tissues, & Organs simple --> complex • Body Symmetry asymmetrical --> radial --> bilateral • Cephalization no head --> head • Segmentation no body segments --> specialized body segments • Coelom Formation (body cavity) acoelomate --> pseudocoelomate --> true coelom • Embryological Development protostome --> deuterostome Comparing Invertebrates Major Characteristics Sponges Cnidarians Flatworms Roundworms Germ Layers Absent Two Three Three Body Symmetry Absent Radial Bilateral Bilateral Cephalization Absent Absent Present Present Section 29-1 Coelom Absent Absent Absent Pseudocoelom Early Development — — Protostome Protostome Major Characteristics Annelids Mollusks Arthropods Echinoderms Germ Layers Three Three Three Three Body Symmetry Bilateral Bilateral Bilateral Radial (adults) Cephalization Present Present Present Absent (adults) Coelom True coelom True coelom True coelom True coelom Early Development Protostome Protostome Protostome Deuterostome Comparing Invertebrates Chart Invertebrate Digestive Systems simplest animals: intracellullar digestion (inside cells) complex animals: extracellular digestion (digestive tract) Intestine Gizzard Crop Pharynx Mouth Mouth/anus Gastrovascular cavity Anus Gastrovascular cavity Annelid Cnidarian Pharynx Crop Anus Pharynx Mouth Mouth/anus Flatworm Stomach and digestive glands Rectum Intestine Arthropod Invertebrate Respiratory Systems Aquatic invertebrates: diffusion and/or gills Terrestrial invertebrates: book lungs, tracheal tubes, etc. Tracheal tubes Gill Siphons Movement of water Spiracles Insect Mollusk Airflow Spider Book lung Invertebrate Circulatory Systems simplest animals: diffusion through body surface complex animals: heart(s) to pump blood in a circulatory system Heartlike structure Small vessels in tissues Hearts Blood vessels Heart Sinuses and organs Insect Open Circulatory System Blood is partially contained. Blood is pumped into sinuses. Blood comes in direct contact with tissues Blood Heartlike vessels structures Annelid Closed Circulatory System Blood is contained in vessels. More efficient (active animals) Invertebrate Excretory Systems Aquatic invertebrates: diffusion through body tissues. Terrestrial invertebrates: nephridia, malpighian tubules, etc. Excretory Flame cells tubules Flatworm Nephrostome Excretory pore Flame cell Excretory tubule Nephridia Digestive tract Annelid Malpighian tubules Arthropod Invertebrate Nervous Systems (Response) Centralization: nerve cells are more concentrated. Cephalization: ganglia are organized into a brain (controls body) Specialization: special sense organs to detect light, sound, movement, etc. Arthropod Brain Ganglia Ganglia Brain Nerve Cells Flatworm Mollusk Cnidarian Movement and Support Hydrostatic skeleton: fluid filled body cavity that supports muscles. Exoskeleton: hard outer skeleton made of chitin Endoskeleton: internal structural support Type of Skeleton Sponges Cnidarians Hydrostatic X Flatworms X Roundworms X Exoskeleton Endoskeleton Type of Skeleton Hydrostatic Exoskeleton Endoskeleton Simple (spicules or spongin) Annelids X Mollusks Arthropods Echinoderms Some Some (shells) X X Reproduction Asexual: reproduce rapidly in favorable conditions (genetically identical) Sexual: creates genetic diversity with a combination of sperm and egg QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. QuickTime™ and a TIFF (Uncompressed) decompressor are needed to see this picture. Porifera Arthropoda Reproduce asexually (budding) or sexually by releasing sperm which fertilizes and egg. (external fertilization) Reproduce sexually when male deposits sperm inside the female to fertilize eggs. (internal fertilization)