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Chapter 24 Introduction to AnimalsSection 1: Animal CharacteristicsSection 2: Animal Body PlansSection 3: Sponges and Cnidarians

24.1 Animal CharacteristicsGeneral Animal FeaturesIntroduction to AnimalsChapter 24The ancestral animals at the beginning of the evolutionary tree are eukaryotic and multicellular.They developed adaptations in structure that enabled them to function in numerous habitats.

Feeding and Digestion Introduction to AnimalsAnimals are heterotrophic.The structure or form of an animals mouth parts determines how its mouth functions.24.1 Animal CharacteristicsChapter 24

SupportIntroduction to AnimalsInvertebratesExoskeletonsHard or tough outer coverings that provide a framework of supportProtect soft body tissuesProvide protection from predators24.1 Animal CharacteristicsChapter 24

SupportIntroduction to AnimalsVertebratesEndoskeletonsProtect internal organsProvide support for the bodyProvide an internal brace for muscles to pull against24.1 Animal CharacteristicsChapter 24

MovementIntroduction to AnimalsThe evolution of nerve and muscle tissues enables animals to move in ways that are more complex and faster than organisms in other kingdoms.24.1 Animal CharacteristicsChapter 24

ReproductionIntroduction to AnimalsFertilization occurs when the sperm penetrates the egg to form a fertilized egg cell called the zygote.Internal fertilizationExternal fertilization24.1 Animal CharacteristicsChapter 24

Introduction to AnimalsAsexual reproduction means that a single parent produces offspring that are genetically identical to itself.BuddingFragmentationRegenerationParthenogenesis24.1 Animal CharacteristicsChapter 24

Early Development Introduction to AnimalsThe zygote undergoes mitosis and a series of cell divisions to form new cells.The cells continue to divide, forming a fluid-filled ball of cells called the blastula.The blastula continues to undergo cell division as some cells move inward to form a gastrula.24.1 Animal CharacteristicsChapter 24

Introduction to Animals24.1 Animal CharacteristicsChapter 24Cell Differentiation in Animal Development

Introduction to AnimalsTissue DevelopmentEndoderminner layer of cells in the gastrulaEctodermouter layer of cells in the gastrulaMesodermlayer of cells between the endoderm and ectoderm24.1 Animal CharacteristicsChapter 24

Introduction to Animals24.1 Animal CharacteristicsChapter 24

24.2 Animal Body PlansIntroduction to AnimalsEvolution of Animal Body Plans Anatomical features in animals body plans mark the branching points on the evolutionary tree.Relationships on this tree are inferred by studying similarities in embryological development and shared anatomical features.Chapter 24

Introduction to Animals24.2 Animal Body PlansChapter 24

Introduction to AnimalsSymmetry Similarity or balance among body structures of organisms Asymmetry Radial symmetry Bilateral symmetry 24.2 Animal Body PlansChapter 24

Introduction to AnimalsCephalizationThe tendency to concentrate nervous tissue and sensory organs at the anterior end of the animal 24.2 Animal Body PlansChapter 24

Introduction to AnimalsBody Cavities Coelomates 24.2 Animal Body PlansChapter 24

Introduction to AnimalsBody Cavities Pseudocoelomates24.2 Animal Body PlansChapter 24

Introduction to AnimalsBody Cavities AcoelomatesHave solid bodies without a fluid-filled body cavity between the gut and the body wall 24.2 Animal Body PlansChapter 24

The mouth develops from the first opening in the gastrula.Introduction to AnimalsDevelopment in Coelomate Animals ProtostomesDeuterostomesThe anus develops from the first opening in the gastrula.24.2 Animal Body PlansChapter 24Visualizing Protostomes and Deuterostomes

Introduction to AnimalsSegmentationSegmented animals can be put together from a succession of similar parts.Can survive damage to one segmentMovement is more effective24.2 Animal Body PlansChapter 24

24.3 Sponges and CnidariansIntroduction to AnimalsSpongesSponges do not develop tissues.Collar cells with flagella line the inside of the sponge and whip back and forth drawing water into the body of the sponge.Water and waste materials are expelled from the sponge through the osculum.Chapter 24

Introduction to Animals24.3 Sponges and CnidariansChapter 24A Sponge

Introduction to AnimalsFilter FeederFood particles cling to the cells.Digestion of nutrients takes place within each cell.24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsArchaeocytes Specialized cells that secrete spicules, which are the support structures of spongesSpicules are small, needlelike structures made of calcium carbonate, silica, or a tough fibrous protein called spongin24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsSponge Diversity DemospongiaeCalcareaHexactinellida24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsReproductionReproduce asexuallyFragmentationBuddingGemmulesReproduce sexuallyEggs remain within a sponge.Sperm are released into the water.24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsCnidariansHave one body opening and two layers of cellsOuter layer functions in protecting the internal bodyInner layer functions mainly in digestion24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsFeeding and DigestionTentacles are armed with stinging cells called cnidocytes.A nematocyst is a capsule that holds a coiled tube containing poison and barbs.Water inside an undischarged nematocyst is under an osmotic pressure of more than 150 atmospheres.24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsAs the osmotic pressure increases, the nematocyst discharges forcefully. A barb is capable of penetrating a crab shell. 24.3 Sponges and CnidariansChapter 24http://en.wikipedia.org/wiki/Cnidocyte

Introduction to AnimalsCells lining the gastrovascular cavity release digestive enzymes over captured prey. Undigested materials are ejected though the mouth. 24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsResponse to Stimuli A nerve net conducts impulses to and from all parts of the body.The impulses cause contractions of musclelike cells in the two cell layers.24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsReproductionTwo body formsPolypMedusa24.3 Sponges and CnidariansChapter 24

Introduction to AnimalsThe two body forms of cnidarians can be observed in the life cycle of jellyfishes.24.3 Sponges and CnidariansChapter 24A Cnidarian

Introduction to AnimalsCnidarian Diversity HydroidsJellyfishesSea anemones and corals24.3 Sponges and CnidariansChapter 24Comparison of Sponges and CnidariansPart 1 Part 2

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