P10-Lecture 21 - Animals I- March 31

P10-Lecture 21 - Animals I- March 31 - Announcements s Exam...

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Unformatted text preview: Announcements s Exam 2 Friday - April 9 s Exam review - Wednesday April 7 x HJP 0226 6 -7 pm s Exam Review posted this Friday s Sample Lab Practical questions are under Lab Information tab on elmsModule 2. s Three Groups for us Eukaryote Diversity (In Brief) x 1) Most basal lineage of eukaryotes x 2)"Photosynthetic" - E.g. Plants x 3) "Non-Photosynthetic" - E.g. Fungi, Animals 1 See Fig. 29.8 2 3 Three Origins of Multicellularity s Plants s Fungi s Animals x Fungi more closely related to us than to plants. 3 Molecular 3 Chitin 3 Store evidence (proteins & rRNA similar) 31.8 glycogen x Animals and fungi independently multicellular What is the largest living organism on the planet? Chpt. 32: Animals On the move & Land Ho What are animals (= Metazoans)? s Eukaryotes s Multicellular x x x x Nervous & muscle tissue Structural proteins 3 Ex: Collagen Motile (at least part of life cycle) Sexual reproducers (some asexual) s Heterotrophic s Embryonic development s Hox genes with specific DNA sequences only in animals Animal relationships Metazoa = Animalia Eumetazoa Bilateria Porifera (sponges) Radiata Cnidaria Themes: 1) Mobility 2) Land (again) Kingdom Animalia Multicellular, eukaryotic, and heterotrophic Metazoa - From where? s Animals have their origins among the "protists" s Multicellularity independent of plants, fungi s In particular, Choanoflagellates x Colonial tendency x Feeding similarity x Very similar to choanocytes of sponges! 32.11a Porifera- Examples of early animals s No true tissues s Only 2 cell types x Choanocytes x Amoebocytes x Some totipotent s Hermaphrodites x Asexual regeneration x Larvae swim Porifera s Adults sessile s Skeletal fibers in middle layer s Filter feeders x Full of holes x Create current with choanocytes flagella 32.11b Animal relationships Metazoa = Animalia Eumetazoa Bilateria Porifera (sponges) Radiata Cnidaria Kingdom Animalia Multicellular, eukaryotic, and heterotrophic Eumetazoa s Diploblastic s Two tissue layers x Endoderm (inside) x Ectoderm (outside) s E.g. Cnidarians x Jellyfish, anemones, corals Eumetazoa s Diploblastic s Two tissue layers x Endoderm (inside) x Ectoderm (outside) s E.g. Cnidarians x Jellyfish, anemones, corals 32.3a Early Embryonic Development in Animals Gastrulation Zygote Cleavage blastula gastrula See Fig. 32.8b Cnidarians- Diploblastic s Two phases in the life cycle (usually) x Polyp x Medusa s Reproduce x Sexual x Asexual 3 budding See Fig. 32.27 Cnidarians 32.5b Cnidarians s Nematocysts (in cnidocytes) x Stinging organelles x Nerve net Animal relationships Metazoa = Animalia Eumetazoa Bilateria "Porifera" (sponges) "Radiata" Cnidaria Eumetazoa Gastrulation Nervous system, synpases Radial Symmetry Animal relationships Ctenophores s Beautiful (comb jellies) s Superficially like Cnidarians- radial s Quite complicated, in some ways like Bilaterians s Have been a problem phylogenetically for a long time! s See Fig. 32.10 Metazoa = Animalia Eumetazoa Bilateria "Porifera" Cnidaria "Radiata" (sponges) ctenophores Eumetazoa Gastrulation Nervous system, synpases Radial Symmetry Animal origins and diversification s At least 700 mya- 1st seen s Apparently very rapid diversification ~540 mya x Cambrian Explosion x Earlier fossils are jellyfish, mollusks, or tracks & burrows x Most other modern phyla appear within 40 million years of this time i.e. Burgess Shale Burgess Shale- British Columbia, Canada What sets the Bilaterians apart? Metazoa = Animalia Eumetazoa Bilateria "Porifera" (sponges) "Radiata" Cnidaria Eumetazoa Gastrulation Nervous system, synpases Radial Symmetry Bilateral symmetry and Cephalization s Cephalization x Development of head x Sense organs in front Bilateral animals s Bilateral symmetry xEqually divided into 2 Fig. 32.5c planes xanterior xposterior xDirection in movement VS. Origin of Bilateria s Cephalization s Bilateral symmetry s Triploblasty! xA third tissue layer xMesoderm 3Forms more muscle 3Supports organs 32.6a Metazoa = Animalia Animal relationships Eumetazoa Bilateria Porifera (sponges) Radiata Cnidaria Bilateria Bilateral symmetry Triploblastic body= mesoderm Eumetazoa Cephalization Diploblastic body = endoderm and ectoderm Kingdom Animalia Multicellular, eukaryotic, and heterotrophic Two Great Branches of the Bilaterian Tree s Protostomes x Lophotrochozoa 3 E.g. 3 E.g. Annelids Arthropods x Ecdysozoa s Deuterostomes x E.g. Chordates See 34.3 Protostomes vs. Deuterostomes s Protostomes x Blastopore -> mouth s Deuterostomes x Blastopore -> anus 32.8b Bilaterial animals and the Coelom s Coelom = fluid-filled body cavity s Three types x Acoelom (no cavity) x Pseudocoelom x True coelom 3 Evolved multiple times See 32.6 The Coelom Primitive Primitive absence absence 2* Loss 2* Loss Convergence Convergence Fig 32.9 modified Fig 33.6 modified Coelom is NOT a reliable guide to phylogeny. Flatworms: Acoelomates s Flatworms- simplest bilateral animals s Many are parasites x Tapeworms x Flukes s Free living x E.g. planaria Flatworms-Flukes Human liver fluke Flatworms-Tapeworms Pseudocoelom advantages (vs. none) s Hydrostatic skeleton x More effective locomotion See 32.7b vs. s Easier internal transport s Storage of materials s Gamete maturation site s Enlargement of organs s Phylum Nematoda x Pseudocoelomate x Often parasitic 3 Ex: Roundworms pinworm, hookworm, heartworm 3 Trichinella spiralis x Extremely abundant x Decomposers C. elegans in soil Trichinella infection Pinworm Advantages of a true coelom (vs. pseudo) s Same as pseudocoelom, plus: x Better interaction of mesoderm, endoderm x Better support of organs x Better digestion Protostomes: Annelida s Segmentation x Can operate segments independently 3 Coelom x Redundancy See 46.18 Protostomes: Arthropoda s Extremely diverse x Aquatic and terrestrial s Segmentation x Jointed Skeleton 3 External = Exoskeleton 3 Jointed skeleton convergent with vertebrates x Redundancy and Serial Homology! 3 And extreme specialization! Comments on Segmentation s Evolved multiple times x Annelids x Arthropods x Chordates 32.10 Modified s Associated with diversity s Mollusks Phylum Mollusca x Radula- feeding organ is unique to group x Similar body plan: 3 Muscular foot, mantle, visceral mass Phylum Mollusca s 4 example classes: x 1. Chitons- 8 plates in shell x 2. Bivalves- 2 sided shells Phylum Mollusca x 3. s 4 example classes: Gastropods- snails & slugs 3 Torsion x 4. Cephalopods- squid, octopus, cuttlefish, chambered nautilus 3 Closed circulatory system 3 Well-developed sense organs in squid & octopus Phylum Annelida s Segmented worms s Coelom highly developed s Hermaphrodites Annelids s 3 groups: x 1. Earthworms x 2. Polychaetes 3 aquatic worms 3 largest group x 3. Leeches s Jointed appendages Arthropods s Regional segmentation s Exoskeleton (chitin) x molting s Open circulatory system Phylum Arthropoda s Most successful of all animal phylas 5 major groups: s 1. Trilobites (all extinct) Arthropods s 2. Chelicerates Arachnids: spiders, mites, ticks, scorpions x Horseshoe crabs; Arthropods s 3. Millipedes & Centipedes x Millipedes- 2 pair legs/ body segment x Centipedes- 1 pair legs/body segment 3 Pair of poison claws Arthropods s 4. Crustaceans Crabs, lobsters, shrimp, isopods, copepods ... x Ex: -specialized appendages -2 pair of antennae s 5. Insects *most numerous and diverse of all animal species *metamorphosis during development 3-part body Adapted mouthparts 3 pair legs 1 or 2 pair wings Success of insects comes from their ability to fly wings! ...
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This note was uploaded on 05/11/2010 for the course BIOLOGY 105 taught by Professor Richard during the Spring '10 term at George Mason.

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