*Chapter 32Friday, April 1, 20161:50 PM Chapter 32 - Overview of Animal Diversity Features of Kingdom Animalia-Animal Structure and FunctionoMulticellular eukaryotes-Most with differentiated cells, tissues, organs, organ systems-(Epithelial, nerve, muscle tissue cells)oCells with no cell wallsoCells 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 movementoMost 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 proteinsoMost 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 fluidoAlmost all are ingestive heterotrophs-But some parasites are absorptive-Animal Life CycleoSexual reproduction in almost all-Most: separate sexes (but sex may change)-Some: hermaphoditic = M/F in one individualoAsexual reproduction in some-Fragmentation and regeneration-Budding-Rare: parthenogenesis = virgin females produce eggs that develop into offspringoDiploid life, except sperm and egg-Except some: all males are haploidoWith 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 anusoMost 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 AnimalsoChoanoflagellates are closest protist group to animals-First animals were sponge-like (710 mya)-Able to trap little bits of food-Proterozoic (Pre-Cambrian) AnimalsoEdiacaran biota ~566 mya-Earliest known animal fossils; many extinct-Soft-bodied: sponges; jellyfish-like; worm-like-Paleozoic Era Animalso"Cambrian explosion" ~535 million years ago-Dramatic animal diversification-Almost all major phyla (+others, extinct)-First mineralized skeletons, shellsoLater 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 AnimalsoDinosaurs, pterosaurs, aquatic reptilesoOrigin of birds and mammals (early ancestors of modern birds))oEnd: cretaceous extinctions (asteroid hit basin in Mexico, leading to cascade of extinctions)-Cenozoic Era AnimalsoDiversification of modern groupsAnimal Body Plans-Most Animals are SymmetricoRadial symmetry-Meets world at 360 degrees-Important for sessile animals, that are attached to something, helping it respondto the world-Usually sessile (attached) or planktonic (drifting) lifeOral side up, aboral side downoBilateral 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 LayersoDiploblastic-With two germ layers (form in gastrula stage):Ectoderm - outer covering and nervesEndoderm - digestive tract; internal organs-In higher animals, also internal organsoTriploblastic-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 Cavityo= fluid-filled space between body wall and gut (digestive tract)oFunctions:-Cushions internal organs-Allows independent movement and expansion of gut-The fluid can act as a hydrostatic skeletonSomething for muscles to push againstoMost 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)oSome body cavities are pseudocoeloms-No mesoderm between cavity and gut-"Fake" coelom-Ex. NematodesoAcoelomates have no body cavity-"a-" = "without"-Ex. Platyhelminthes-No space between endoderm and mesodermoDevelopmental PatternsoProtostome 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 deathoDeuterostome 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 emmoAnimal PhylogenyoEdysozoa (shedding skin)-Add: Onychophora and