Chapter 32 Friday April 1 2016 1 50 PM Chapter 32 Overview of Animal Diversity Features of Kingdom Animalia Animal Structure and Function o Multicellular eukaryotes Most with differentiated cells tissues organs organ systems Epithelial nerve muscle tissue cells o Cells with no cell walls o Cells joined together by Protein rich extracellular matrix ECM With collagen unique to animals Protein junctions Tight junctions prevent acids from leaking out into the rest of the body Desmosomes secure connections that hold cells together especially ones that are close in movement o Most have nerve cells neurons and muscle cells Unique to animals Allows motor response to stimulus Producing movement Neurons transmit signals Electrically along their membranes And chemically at synapses with other cells REC Synapses are the primate site of control and processing signals Muscle cells contract shorten due to bundles of sliding filaments of actin and myosin proteins o Most with interacting organ systems Exchange chemicals with external environment Maintain internal homeostasis steady state through feedback mechanisms Some have circulatory systems that transport nutrients throughout the body Interstitial fluid o Almost all are ingestive heterotrophs But some parasites are absorptive Animal Life Cycle o Sexual reproduction in almost all Most separate sexes but sex may change Some hermaphoditic M F in one individual o Asexual reproduction in some Fragmentation and regeneration Budding Rare parthenogenesis virgin females produce eggs that develop into offspring o o o Diploid life except sperm and egg Except some all males are haploid With embryonic development Most animals have similar genes that control development including Hox genes Zygote go through series of division called cleavage blastula stage Then gastrulation forms the gastrula cells moving around and pulling other cells and reorganizing other cells that set the stage for the body plan for the animal With blastopore opening into the archenteron and archenteron inner chamber Creates germ layers origins of tissues Protostome blastopore becomes mouth Deuterostomes blastopore becomes anus Most have larval stage before adulthood Larva differs in form function and often habitat from adult Goes through metamorphosis to adult form Animal without a larval stage is juvenile adult is sexually mature Animal Origin and Fossil History One Common Ancestor of Animals o Choanoflagellates are closest protist group to animals First animals were sponge like 710 mya Able to trap little bits of food Proterozoic Pre Cambrian Animals o Ediacaran biota 566 mya Earliest known animal fossils many extinct Soft bodied sponges jellyfish like worm like Paleozoic Era Animals o Cambrian explosion 535 million years ago Dramatic animal diversification Almost all major phyla others extinct First mineralized skeletons shells o Later Paleozoic Era Vertebrate fishes dominate seas Arthropods invade land Later vertebrates invade land amphibians Finally fist reptile like amniotes animals that were able to lay eggs and reproduce on land Mesozoic Era Animals o Dinosaurs pterosaurs aquatic reptiles o Origin of birds and mammals early ancestors of modern birds o End cretaceous extinctions asteroid hit basin in Mexico leading to cascade of extinctions Cenozoic Era Animals o Diversification of modern groups Animal Body Plans Most Animals are Symmetric o Radial symmetry Meets world at 360 degrees Important for sessile animals that are attached to something helping it respond to the world Usually sessile attached or planktonic drifting life Oral side up aboral side down o Bilateral symmetry Meets world at one end left and right side Usually with head concentration of sensory organs at anterior cephalization active lifestyle Active lifestyle Anterior front Posterior end of body Dorsal backbone on dorsal side away from substrate Ventral closest to gravity Most Animals Have 2 or 3 Tissue Layers o Diploblastic With two germ layers form in gastrula stage Ectoderm outer covering and nerves Endoderm digestive tract internal organs In higher animals also internal organs o Triploblastic With all 3 germ layers Mesoderm muscles and endoskeleton important and associated with true muscles Develops between ectoderm and endoderm Most Animals Have a Body Cavity o fluid filled space between body wall and gut digestive tract o Functions Cushions internal organs Allows independent movement and expansion of gut The fluid can act as a hydrostatic skeleton Something for muscles to push against o Most body cavities are true coeloms Completely lined with mesoderm Gut is supported and has muscles Tissue layer lining coelom and suspending internal organs from mesoderm o Some body cavities are pseudocoeloms No mesoderm between cavity and gut Fake coelom Ex Nematodes o o o o o o Acoelomates have no body cavity a without Ex Platyhelminthes No space between endoderm and mesoderm Developmental Patterns Protostome development Annelids Mollusks Blastopore of gastrula becomes adult mouth Protostome cleavage is determinate Cells as they divide become very specialized Early embryonic cells fated to become certain body parts Lose any early cell defect or death Deuterostome development Echinoderms Chordates second mouth Blastopore of gastrula becomes adult anus second opening becomes mouth Deuterostome cleavage is indeterminate Any early cell can become complete organism Explains why deuterostomes can have identical twins Removing one cell does not injure the emm Animal Phylogeny Edysozoa shedding skin Add Onychophora and Tardigrada