Chapter 32 – Animal Diversity

Chapter 32 Animal Diversity

Chapter 32 Animal Diversity32.1 Animals are multicellular, heterotrophic eukaryotes with tissues that develop from embryonic layersAnimals have the following characteristics:Multicellular heterotrophsMost have muscle & nervous tissueMost reproduce sexually, with a flagellated sperm & a large egg which unite to form a diploid ZYGOTEThe diploid stage dominates the life cycle1.3 million living speciesVocabZygoteFertilized eggCleavagesSuccessive mitotic cell divisions without cell growth between cyclesBlastulaHollow ball of cells surrounding a cavity called the blastocoelGastrulaAs the blastula is punched in, the embryonic tissue layers will formEctodermThe outer tissue layerEndoderm The inner tissue layerBlastoporeOpening into the gastrula Becomes the mouth in protosomesBecomes the anus in deuterostomesArchenteronBlind pouch formed by gastrulation

Some animals have larvaeImmature form distinct from the adult stage they will undergo metamorphosisAnimals share HOX GENESUnique family of genes that play important roles in developmentCan produce a wide diversity of animal morphology

32.3 Animals & Their Body PlansSymmetryNone (sponges)RadialBilateralRadial occurs in:JellyfishAny cut through the central axis would produce mirror images

Bilateral occurs in - LobstersHumansHave a right & left sideSingle cut would divide the animal into 2 mirror image halvesDorsal side (back)Ventral side (belly)Anterior (head)Posterior (tail)Cephalization

TissuesAnimal body plans vary according to the organization of the animals tissuesTissues are collections of specialized cells isolated from other tissues by membranous layersDuring development, three germ layers give rise to the tissues and organs of the animal embryo

Ectoderm is the germ layer covering the embryos surfaceEndoderm is the innermost germ layer and lines the developing digestive tube, called the archenteronMesoderm is the middle layerDiploblastic animals have ectoderm and endodermTriploblastic animals also have an intervening mesoderm layer; these include all bilaterians

Body CavitiesMost triploblastic animals possess a body cavity3 types:1) A coelomate possesses a true body cavity Derived from mesodermFilled with fluidSeparates an animals digestive tract from the outer wallEarthworms

2) PseudocoelomateTriploblastic animalsCavity formed from mesoderm & endodermRoundworms

----- Meeting Notes (3/30/12 15:00) -----Mr.Norman joey josephdonaldjoseph 183) AcoelomatesNo cavities between alimentary canal & outer wall of bodyFlatworms

Functions of Body Cavities1) Cushion suspended organs2) Act as a hydrostatic skeleton3) Enable internal organs to grow & move independently Protostome & Deuterostome Development3 major differences:1) Cleavage2) Coelom formation3) Fate of the blastoporeCleavage:P = begins with spiral, determinate cleavageD = radial, indeterminate cleavage

Coelom Formation:Begins in the gastrula stage P = coelom forms from splits in the mesodermD = coelom forms from mesodermal outpocketings of the archenteron

Fate of the Blastospore:P = mouth forms from the blastoporeD = mouth forms from a secondary opening