Chapter22Sum07

Chapter22Sum07 - Major Invertebrate Animal Groups...

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Unformatted text preview: Major Invertebrate Animal Groups Poriferans Cnidarians Flatworms Annelids Mollusks Arthropods -over 1,000,000 existing species Roundworms Echinoderms What does invertebrate mean? 1 2 3 4 5 6 DIPLOID M e i o s i s Sperm Eggs Zygote (fertilized egg) Blastula (cross section) Early gastrula (cross section) Later gastrula (cross section) Outer cell layer (ectoderm) Inner cell layer (endoderm) Opening Larva Digestive tract M e t a m o r p h o s i s Adult 7 HAPLOID Not all animals have larval stage! A middle layer called mesoderm develops later in many animals. Invertebrate Evolution Chapter 22 Cells in these protists gradually became more specialized and layered The animal kingdom probably originated from colonial protists 1 Early colony of protists; aggregate of identical cells 2 Hollow sphere (shown in cross section) 3 Beginning of cell specialization (cross section) 4 Infolding (cross section) 5 Gastrula-like protoanimal (cross section) Digestive cavity Reproductive cells Somatic cells Terminology Coelom body cavity lined with thin layer of tissue from mesoderm Pseudocoelom body cavity not completely derived from mesoderm Acoelomate no body cavity Protostome mouth forms from blastopore in developing embryo Deutorostome anus forms from blastopore Body symmetry Radial symmetry equal halves from any plane through a central axis. (2 embryonic tissue layers) Bilateral symmetry mirror image halves along one particular plane through central axis. (3 embryonic tissue layers) Fig. 22-2a, p.354 radial symmetry Fig. 22-2b, p.354 d o r s a l a n t e r i o r p o s t e r i o r v e n t r a l bilateral symmetry Sponges Sponges No symmetry No tissues No organs Filter feeders Fibers in cell wall help protect Fig. 22-6c, p.357 section through body wall: glasslike structural elements amoeboid cell pore semifluid matrix flattened surface cells collar cell with a central flagellum ringed by microvilli Gemmules Ectoderm Endoderm Digestive cavity Two-layers Mesoderm Cnidarians have true tissues derived from two embryonic layers Derived from: Cnidarians two tissue layers but no internal organs Jellyfish Nematocysts on surface can release toxins or entangle prey Sea wasp contains one of the most toxic of all known venoms Polyp body form: (stationary) Medusa body form: (move freely) The two body plans of the cnidarians Tentacles Mouth Gastrovascular Cavity: 1) Food in/out 2) Serves as a support 3) Circulates materials Polyp Medusa Mouth Tentacles Ectoderm Endoderm Amoeboid jelly cells Fig. 22-7, p.358Fig....
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Chapter22Sum07 - Major Invertebrate Animal Groups...

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