introduction to invertebrates chapter 29. introduction to invertebrates 2outline evolution of...

Introduction to Invertebrates

Chapter 29

2Introduction toIntroduction to Invertebrates Invertebrates

OutlineOutline

Evolution of AnimalsEvolution of AnimalsMulticellularityMulticellularity

SpongesSpongesTrue TissuesTrue Tissues

Cnidarians and Comb JelliesCnidarians and Comb Jellies HydraHydra ObeliaObelia

Bilateral SymmetryBilateral Symmetry FlatwormsFlatworms RoundwormsRoundworms

Body CavitiesBody Cavities AcoelomatesAcoelomates PsuedocoelomatesPsuedocoelomates EucoelomatesEucoelomates


Evolution of AnimalsEvolution of Animals

All animals are multicellular All animals are multicellular heterotrophic organisms that must heterotrophic organisms that must take in preformed foodtake in preformed food

Classification CriteriaClassification Criteria

Level of organizationLevel of organization

Cellular, tissue, organ Cellular, tissue, organ

Body PlanBody Plan

Sac, tube-within-a-tubeSac, tube-within-a-tube

SegmentationSegmentation

Segmentation leads to specializationSegmentation leads to specialization


Evolution of AnimalsEvolution of Animals

Classification Criteria, contClassification Criteria, contSymmetrySymmetryRadial - Two identical halvesRadial - Two identical halvesBilateral - Definite right and left halvesBilateral - Definite right and left halves

Type of CoelomType of CoelomPseudocoelomPseudocoelomCoelomCoelom

Early Developmental PatternEarly Developmental PatternProtostome - First embryonic opening Protostome - First embryonic opening becomes the mouth becomes the mouth Dueterostome - Second embryonic Dueterostome - Second embryonic opening becomes the mouthopening becomes the mouth

5Animals:Multicellular, Heterotrophic

Eukaryotes

6 Traditional Phylogenetic Tree of Animals


MulticellularityMulticellularitySpongesSponges

Only level of animal to have cellular Only level of animal to have cellular organizationorganization

Saclike bodies perforated by many poresSaclike bodies perforated by many pores

Beating of flagella produces water Beating of flagella produces water currents that flow through pores into currents that flow through pores into central cavity and out osculumcentral cavity and out osculum

Sessile filter feedersSessile filter feeders

Asexual reproduction by fragmentation or Asexual reproduction by fragmentation or buddingbudding

8 Simple Sponge Anatomy


True Tissue LayersTrue Tissue Layers

Total of three possible germ layersTotal of three possible germ layers

EctodermEctoderm

Endoderm, andEndoderm, and

MesodermMesoderm

phlya Ctenophora and Cnidaria phlya Ctenophora and Cnidaria develop only ectoderm and endodermdevelop only ectoderm and endoderm

DiploblastsDiploblasts

Radially symmetricalRadially symmetrical


Comb JelliesComb Jellies

Small, transparent, and often Small, transparent, and often luminescentluminescent

Most of body composed of mesogleaMost of body composed of mesoglea

Largest animals propelled by beating Largest animals propelled by beating of ciliaof cilia

Capture prey with tentaclesCapture prey with tentacles

11 Comb Jelly Compared to Cnidarian


CnidariansCnidarians

Tubular animals that most often Tubular animals that most often reside in shallow marine watersreside in shallow marine waters

Polyp and medusa body formsPolyp and medusa body forms

Specialized stinging cells (cnidocytes)Specialized stinging cells (cnidocytes)

Fluid-filled capsule, nematocystFluid-filled capsule, nematocyst

Two-layered body sacTwo-layered body sac

Outer layer - Protective epidermisOuter layer - Protective epidermis

Inner layer - Gastrovascular cavityInner layer - Gastrovascular cavity

Nerve net found throughout body Nerve net found throughout body

13 Cnidarian Diversity


HydraHydra

Freshwater cnidarianFreshwater cnidarian

Small tubular poly body about one-Small tubular poly body about one-quarter inch in lengthquarter inch in length

Gastrovascular cavity is central cavityGastrovascular cavity is central cavity

Tentacles can respond to stimuliTentacles can respond to stimuli

Can reproduce sexually and asexuallyCan reproduce sexually and asexually

15 Anatomy of Hydra


ObeliaObelia

A colony of polyps enclosed by a hard, A colony of polyps enclosed by a hard, chitinous coveringchitinous covering

Feeding polypsFeeding polyps

Extend beyond coveringExtend beyond covering

Have nematocyst-bearing tentaclesHave nematocyst-bearing tentacles

Reproductive polypsReproductive polyps

Budding of new polypsBudding of new polyps

Also has sexual reproduction Also has sexual reproduction (medusae) stage(medusae) stage

17 Obelia Life Cycle


Bilateral SymmetryBilateral Symmetry

Ribbon worms (phylum Nemertea)Ribbon worms (phylum Nemertea)

Have distinctive proboscisHave distinctive proboscis

Flatworms (phylum Platyhelminthes)Flatworms (phylum Platyhelminthes)

Majority are parasiticMajority are parasitic

Organ-level organizationOrgan-level organization

No specialized circulatory or respiratory No specialized circulatory or respiratory structuresstructures

Have undergone cephalizationHave undergone cephalization

Ladder-type nervous systemLadder-type nervous system

19 Ribbon Worm, Lineus


Free-living FlatwormsFree-living Flatworms

Planarians (genus Dugesia)Planarians (genus Dugesia)

Live in freshwater habitatsLive in freshwater habitats

Head is bluntly arrow shapedHead is bluntly arrow shaped

Auricles function as sense organsAuricles function as sense organs

Two light-sensitive eye spotsTwo light-sensitive eye spots

Three kinds of muscle layers:Three kinds of muscle layers:

Outer circular layerOuter circular layer

Inner longitudinal layerInner longitudinal layer

Diagonal layerDiagonal layer

21Planarian Anatomy


PlanariansPlanarians

Planarians, cont.Planarians, cont.

Excretory organ functions in osmotic Excretory organ functions in osmotic regulation and water excretionregulation and water excretion

Can reproduce asexuallyCan reproduce asexually

HermaphroditicHermaphroditic

Practice cross-fertilizationPractice cross-fertilization


Parasitic FlatwormsParasitic Flatworms

Parasitic flatworms are flukes Parasitic flatworms are flukes (trematodes) and tapeworms (trematodes) and tapeworms (cestodes)(cestodes)

Well-developed nerves and Well-developed nerves and gastrovascular cavity are unnecessarygastrovascular cavity are unnecessary

FlukesFlukes

Reproductive system well developedReproductive system well developed

Usually hermaphroditicUsually hermaphroditic

24Life Cycle of Schistosomiasis


Parasitic FlatwormsParasitic Flatworms

TapewormsTapeworms

Have anterior region with Have anterior region with modifications for attachment to modifications for attachment to intestinal wall of hostintestinal wall of host

Behind head region, scolex, a long Behind head region, scolex, a long series of proglottids are foundseries of proglottids are found

Segments each containing a full set of Segments each containing a full set of both male and female sex organsboth male and female sex organs

Complicated life cyclesComplicated life cycles

26Life Cycle of a Tapeworm, Taenia


PseudocoelomPseudocoelomPseudocoelom:Pseudocoelom:

A “false” body cavity that is A “false” body cavity that is incompletely lined by mesodermincompletely lined by mesoderm

Provides a space for internal organs Provides a space for internal organs and can serve as hydrostatic skeletonand can serve as hydrostatic skeleton

Roundworms (phylum Nematoda)Roundworms (phylum Nematoda)

Non-segmented, generally colorless Non-segmented, generally colorless wormsworms

Several parasitic roundworms infect Several parasitic roundworms infect humanshumans

28Roundworm Anatomy


Parasitic RoundwormsParasitic Roundworms

Ascaris Ascaris – Intestinal roundworm– Intestinal roundworm

Trachinella Trachinella - Trichinosis- Trichinosis

Dirofilaria Dirofilaria - Heartworms- Heartworms

Wuchereria Wuchereria - Elephantiasis- Elephantiasis

30Filarial Worm


RotifersRotifers

Rotifers (phylum Rotifera)Rotifers (phylum Rotifera)

Named for crown of cilia resembling a Named for crown of cilia resembling a rotating wheelrotating wheel

Serves as both as an organ of Serves as both as an organ of locomotion and aids direction of food locomotion and aids direction of food to mouthto mouth

32Rotifer


ReviewReview

Evolution of AnimalsEvolution of AnimalsMulticellularityMulticellularity

SpongesSpongesTrue TissuesTrue Tissues

Cnidarians and Comb JelliesCnidarians and Comb Jellies HydraHydra ObeliaObelia

Bilateral SymmetryBilateral Symmetry FlatwormsFlatworms RoundwormsRoundworms

Body CavitiesBody Cavities AcoelomatesAcoelomates PsuedocoelomatesPsuedocoelomates EucoelomatesEucoelomates

Introduction to Invertebrates

Ending Slide Chapter 29

introduction to invertebrates chapter 29. introduction to invertebrates 2outline evolution of...

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