Chapter 32 & 33 Kingdom Animilia Over 1.5 million species Estimated 73 million 35 Phylums Over half are insects More similarities within animal genomes than other kingdoms Characteristics  Multicellular Lack of cell wall Sexual reproduction mobile sperm larger non-motile egg Nervous Tissue Complexity Responsiveness Hox Genes Special clusters of genes associated with the planning of the body Metazoans All animals Multicellular animals Paratoans Sponges Eumetazoans "true" multicellular animals Classification/Systematics Old Morphology Embryonic Development Recent Molecular genetics Body Plans Morphological and Developmental Features Body Symmetry Number of tissue Layers Patterns of Embryonic development  Symmetry Eumetazoa Divided by symmetry Radiata Radial symmetry Often Circular or tubular Bilateria Bilateral symmetry Dorsal Back Ventral Front Anterior Posterior cephalization enlarged head Tissues Metazoa all animals divided on weather or not they have specialized tissues Parazoa Porfera sponges may have distinct cell types Enmetazoa more than one type of tissue organs all other animals Germ Layers Radial 2 layers Diploblastic endoderm ectoderm Bilateral 3 layers Triploblastic endoderm ectoderm mesoderm Embryonic Development Protostome Blastopore becomes mouth cleavage is determinate fate of embryonic cells are determined early Deuterostome (second opening) Blastopore becomes anus cleavage is indeterminate each cell produced by early cleavage can develop into a complete embryo  Other Morphological Characteristics Used in classification Presence or absence or coelom Body segmentation Molecular data suggest these features are unreliable in terms of understanding evolutionary history Body Cavity Coelom a fluid-filled body cavity Coelomate or eucolemate true coelom coelom completely lined with mesoderm Pseudocoelom coelom only partially lined with mesoderm rotifers and roundworms Acoelomate lack of a body cavity and instead have mesenchyme flatworms Flatworm has no mesoderm Functions of the Coelom Cushions internal organs Enables movements and growth of internal organs independent of the body wall Fluid acts as a simple circulatory system Segmentation Body may be divided into regions called segments occurs in annelid worms, arthropods, and chordates allows specialization of body region DO NOT worry about the number of species Molecular views of Animal Diversity Scientist now use molecular techniques to classify animals Compare similarities in DNA, rRNA, and Amino Acids Closely related organisms have fewer differences than those more distantly related Advantages over morphological data in that genetic sequences are easier to quantify and compare Example: A,T,G, and C in DNA Genes used in Molecular Systematics Studies often focus on ribosomal RNA (rRNA) Universal in all organisms changes slowly over time Hox genes also studied often Found in all animals duplications in these genes may have led to evolution of body form Phylogenies constructed using rRNA and Hox genes are similar and often agree with those based on morphology Invertebrates "without backbone" +95% of all species Phylum Porifera Sponges lack tissues (organs) multicellular pores filter H2O and food Invertebrates Phylum Cnidaria Jelly fish, corals, anemones  Diploblastic development Two tissue layers Mesoclea gelatinous covering Nerve net interconnected nerve cells  no brain One opening with gastrovascular cavity Protostomes Invertebrates Radial symmetry Salt and fresh water Stingers Phylum Ctenophora Comb jellies Same characteristics as Cnidaria Strictly salt water No Stingers Phylum Platyhelminthes Flatworms, tapeworms, flukes Triploblastic Organs and organ systems Enhanced nerve net 2 cerebral ganglia One opening with gastrovascular cavity Protostomes invertebrates bilateral symmetry Acoelomate Phylum Rotifera rotifers pseudocoelomate Triploblastic Two openings complete gut tract alimentary canal Protostomes  Corona simple brain invertebrates Phylum Mollusea Snails, slugs, oysters, octopus, squid, clams, muscles Triploblastic Eucoelomate Complete gut tract Protostomes Invertebrates Three part Body Foot Visceral mass Mantle Many have outer shells Phylum Annelida Segmented ring worms Triploblastic Eucoelomate Complete gut tract Protostomes Enhanced nervous system Invertebrates Phylum Nematoda Roundworms Triploblastic Pseudocoelomate Complete gut tract Protostomes Invertebrates Phylum Anthropoda Insects, crustaceans, spiders, ticks Highest diversity of animals >1.5 million species Hardened Exoskeleton Protostomes Invertebrates Eucoelomate Triploblastic Complete gut tract Enhanced nervous system Insects, in particular, have an enhanced brain segmented appendages Phylum Echinodermata sea stars, urchins, sea cucumbers, sand dollars Triploblastic Eucoelomate Complete gut tract Deuterostomes Simple nervous system Endoskeleton series of plates Phylum Chordata Deuterstomes Complete gut tract Endoskeleton Few invertebrates Mostly vertebrates Eucloemates Triploblastic Four Critical Innovations of Chordate Body Design Notochord Dorsal, hollow nerve cord Pharyngeal gill pouches Post-anal tail These four features are exhibited at some point of life history/development Only some Fishes exhibit all four Notochord Cartilaginous supporting rod along the dorsal axis Replaced by jointed "backbone" Vertebral column of hardened cartilage or bone Dorsal, hollow nerve cord Expanded at the anterior end Brian Enclosed/supported/protected by the Notochord Pharyngeal gill pouches Gill slits pharynx back of mouth cavity Post-anal Tail Tail extends posterior of the anus Humans Notochord replaced by vertebrae only pieces left are the inter-vertebral discs between vertebrae  Nerve cord Dorsal, hollow with largest brain capacity (compared to body size) Pharyngeal Pouches Embryonic Development 1 pair retained as Eustachian tubes Post-anal Tail One vertebra as a tail bone (coccyx) Subphylum Urochordata tunicates invertebrates ~3000 species Marine Filter feeders   Subphylum Cephalochordata Lancelets Invertebrates 25 species marine Filter feeders