The Animal Kingdom: An Introduction to Animal Diversity Chapter 29

The Animal Kingdom:The Animal Kingdom:An Introduction to Animal An Introduction to Animal

DiversityDiversity

Chapter 29Chapter 29

Learning Objective 1Learning Objective 1

• What characters are common to most What characters are common to most animalsanimals??

Kingdom AnimaliaKingdom Animalia

• EukaryoticEukaryotic• MulticellularMulticellular• HeterotrophicHeterotrophic• Cells specialized for specific functionsCells specialized for specific functions

StructureStructure

• Body planBody plan• basic structure and functional design of body basic structure and functional design of body

• Animals have diverse Animals have diverse body plansbody plans

FunctionFunction

• Most animalsMost animals• are capable of are capable of locomotionlocomotion at some time at some time

during life cycleduring life cycle• can can respondrespond adaptively to external stimuli adaptively to external stimuli• can can reproducereproduce sexually sexually

Sexual ReproductionSexual Reproduction

• Sperm and egg unite Sperm and egg unite (zygote)(zygote)

• ZygoteZygote undergoes undergoes cleavagecleavage• cell divisions produce hollow ball of cells cell divisions produce hollow ball of cells

(blastula)(blastula)•

• BlastulaBlastula undergoes undergoes gastrulationgastrulation• forms embryonic tissuesforms embryonic tissues

KEY CONCEPTSKEY CONCEPTS

• Animals are multicellular, eukaryotic Animals are multicellular, eukaryotic heterotrophsheterotrophs

Explore the characteristics of Explore the characteristics of animals by clicking on the animals by clicking on the figures in ThomsonNOW.figures in ThomsonNOW.


• Compare the advantages and Compare the advantages and disadvantages of life in the ocean, in fresh disadvantages of life in the ocean, in fresh water, and on landwater, and on land

Marine EnvironmentsMarine Environments

• Provide Provide • relatively stable temperaturesrelatively stable temperatures• buoyancybuoyancy• readily available food readily available food

• Fluid and salt balanceFluid and salt balance• more easily maintained than in fresh water more easily maintained than in fresh water

• Disadvantages:Disadvantages:• currents and other water movementscurrents and other water movements

Fresh WaterFresh Water

• Provides Provides • less constant environmentless constant environment• less food less food

• Animals must osmoregulate Animals must osmoregulate • fresh water is hypotonic to tissue fluid fresh water is hypotonic to tissue fluid

Terrestrial AnimalsTerrestrial Animals

• Have adaptations thatHave adaptations that• protect them from drying out protect them from drying out • protect them from temperature changesprotect them from temperature changes• protect their gametes and embryosprotect their gametes and embryos

Marine and TerrestrialMarine and Terrestrial Environments Environments


• Use current hypotheses to trace the early Use current hypotheses to trace the early evolution of animalsevolution of animals

HypothesesHypotheses

• Proterozoic eonProterozoic eon • most animal clades diverged over long period most animal clades diverged over long period • based on molecular data based on molecular data

• Cambrian RadiationCambrian Radiation• new body plans rapidly evolved among cladesnew body plans rapidly evolved among clades• first fossils of these animalsfirst fossils of these animals

Hox Hox GenesGenes

• Hox Hox genegene group group• controls early development in animal groupscontrols early development in animal groups

• Cambrian periodCambrian period • many many Hox Hox genes had evolved genes had evolved • mutations could have resulted in rapid mutations could have resulted in rapid

changes in animal body planschanges in animal body plans


• How do biologists use How do biologists use structural structural characterscharacters (variations in (variations in body symmetrybody symmetry, , number of number of tissue layerstissue layers, type of , type of body body cavitycavity) and patterns of ) and patterns of early developmentearly development to infer relationships among animal phyla?to infer relationships among animal phyla?

SymmetrySymmetry

• Cnidarians and ctenophores are closely Cnidarians and ctenophores are closely relatedrelated• because they share because they share radial symmetryradial symmetry • most other animals exhibit most other animals exhibit bilateral symmetrybilateral symmetry

• CephalizationCephalization (development of head) (development of head)• evolved with bilateral symmetryevolved with bilateral symmetry

Radial and Bilateral SymmetryRadial and Bilateral Symmetry

Fig. 29-3a, p. 623

Radial symmetry (top view)

Fig. 29-3b, p. 623

Radial symmetry (side view)

Fig. 29-3c, p. 623

Dorsal

Frontal section

Caudal

Anterior Posterior

Cephalic

VentralCross (or transverse) section

Bilateral symmetry (lateral view)

Fig. 29-3d, p. 623

Dorsal

Sagittal section

Medial

Frontal section

Lateral

Ventral

Bilateral symmetry (front view)

Insert “Types of body Insert “Types of body symmetry”symmetry”

symmetry.swfsymmetry.swf

Other Structural CharactersOther Structural Characters

• Relationships can be based onRelationships can be based on• level of level of tissue developmenttissue development• type of type of body cavitybody cavity

• Embryonic tissues (Embryonic tissues (germ layersgerm layers))

Coelom FormationCoelom Formation

Fig. 29-6, p. 626

Schizocoely — characteristic of

protostomes

Enterocoely — characteristic of deuterostomes

Ectoderm EctodermDeveloping mesoderm Blastopore

Presumptive mesoderm

Enterocoelic pouchEndoderm

Mesoderm EctodermEndoderm

GutEctoderm

Developing coelom (Schizocoel) Endoderm

Ectoderm

Gut

Mesoderm

Gut Coelom (Enterocoel)

GutMesoderm

Coelom

Endoderm MesenteryEpidermis (ectoderm)Coelom

Peritoneum (mesoderm)

Muscle layer (mesoderm)

Gut

Fig. 29-6, p. 626

Stepped Art

Schizocoely — characteristic of

protostomes

Enterocoely — characteristic of deuterostomes

Ectoderm EctodermDeveloping mesoderm Blastopore

Presumptive mesoderm

Enterocoelic pouchEndoderm

Mesoderm EctodermEndoderm

GutEctoderm

GutMesoderm

Coelom

Epidermis (ectoderm)

Endoderm MesenteryCoelom

Peritoneum (mesoderm)

Muscle layer (mesoderm)

Gut

Developing coelom (Schizocoel)

EndodermEctoderm

Mesoderm

Gut Coelom (Enterocoel)

Germ LayersGerm Layers

• Outer layer Outer layer (ectoderm)(ectoderm)• gives rise to body covering, nervous systemgives rise to body covering, nervous system

• Inner layer Inner layer (endoderm)(endoderm)• lines the gut and other digestive organslines the gut and other digestive organs

• Middle layer Middle layer (mesoderm)(mesoderm)• gives rise to most other body structuresgives rise to most other body structures

Body PlansBody Plans

Fig. 29-4a, p. 624

Epidermis (from ectoderm)

Muscle layer (from mesoderm)

(a) Acoelomate—flatworm (liver fluke).

Mesenchyme (gelatin-like tissue)

Epithelium (from endoderm)

Fig. 29-4b, p. 624

Pseudocoelom




(b) Pseudocoelomate—nematode.

Fig. 29-4c, p. 624

Coelom



Peritoneum (from mesoderm)


Mesentery (from mesoderm) (c) True coelomate—vertebrate.

Insert “Types of body Insert “Types of body cavities”cavities”

coelom.swfcoelom.swf

Bilateral SymmetryBilateral Symmetry

• AcoelomateAcoelomate• no body cavityno body cavity

• PseudocoelomatePseudocoelomate • body cavity not completely lined with body cavity not completely lined with

mesodermmesoderm

• CoelomateCoelomate, (animal with true , (animal with true coelom)coelom)• body cavity completely lined with mesodermbody cavity completely lined with mesoderm

Bilateral AnimalsBilateral Animals

• Two major evolutionary branches:Two major evolutionary branches:

• ProtostomiaProtostomia• mollusks, annelids, arthropods mollusks, annelids, arthropods

• DeuterostomiaDeuterostomia • echinoderms, chordatesechinoderms, chordates

BlastoporeBlastopore

• Opening from embryonic gut to outsideOpening from embryonic gut to outside

• In In protostomesprotostomes• develops into the mouthdevelops into the mouth

• In In deuterostomesdeuterostomes• becomes the anusbecomes the anus

Cleavage 1Cleavage 1

• ProtostomesProtostomes• undergo undergo spiral cleavagespiral cleavage• early cell divisions diagonal to polar axisearly cell divisions diagonal to polar axis

• DeuterostomesDeuterostomes• undergo undergo radial cleavageradial cleavage • early cell divisions either parallel or at right early cell divisions either parallel or at right

angles to polar axisangles to polar axis• cells lie directly above or below one anothercells lie directly above or below one another

Spiral and Radial CleavageSpiral and Radial Cleavage

Fig. 29-5a, p. 625

Polar axisTop view

Spiral cleavage

Fig. 29-5b, p. 625

Top viewPolar axis

Radial cleavage

Cleavage 2Cleavage 2

• ProtostomesProtostomes• undergo undergo determinate cleavagedeterminate cleavage • fate of each embryonic cell is fixed very early fate of each embryonic cell is fixed very early

• DeuterostomesDeuterostomes• undergo undergo indeterminate cleavageindeterminate cleavage• fate of each embryonic cell is more flexiblefate of each embryonic cell is more flexible

Relationships Based on StructureRelationships Based on Structure

Fig. 29-7, p. 627

Parazoa EumetazoaRadiata Bilateria

Acoelomates Pseudocoelomates Coelomates

Protostomia Deuterostomia

Ch

oan

ofl

agel

late

s

Po

rife

ra

Cn

ida

ria

Cte

no

ph

ora

Pla

tyh

elm

inth

es

Nem

erte

a

Nem

ato

da

Ro

tife

ra

Tar

dig

rad

a

On

ych

op

ho

ra

Art

hro

po

da

An

nel

ida

Mo

llu

sca

Ech

ino

de

rmat

a

Hem

ich

ord

ata

Ch

ord

ata

SegmentationSegmentation

Deuterostome developmentPseudocoelom

True coelom

Radial symmetry

Protostome development

Tissues (ectoderm and endoderm)Multicellularity

Choanoflagellate ancestor

Three tissue layers (mesoderm)Bilateral symmetry


• Biologists classify animals based on their Biologists classify animals based on their body plan and features of their early body plan and features of their early developmentdevelopment


• What are three major contributions to What are three major contributions to animal phylogeny made by animal phylogeny made by molecular molecular systematicssystematics? ?

• Identify the three major clades of Identify the three major clades of bilateral bilateral animalsanimals

Molecular Systematics 1Molecular Systematics 1

• Confirmed much of animal phylogeny Confirmed much of animal phylogeny based on structural charactersbased on structural characters• including axiom that animal body plans including axiom that animal body plans

usually evolved from simple to complexusually evolved from simple to complex


• Provided evidence for exceptions to Provided evidence for exceptions to “simple-to-complex” rule “simple-to-complex” rule

• ExampleExample• molecular data indicate flatworms and ribbon molecular data indicate flatworms and ribbon

worms evolved from more complex animals, worms evolved from more complex animals, became simpler over timebecame simpler over time


• Molecular data suggest pseudocoelomate Molecular data suggest pseudocoelomate animals do not form natural groupanimals do not form natural group• probably evolved from coelomate ancestorsprobably evolved from coelomate ancestors

ProtostomesProtostomes

• 2 clades based on molecular data:2 clades based on molecular data:

• LophotrochozoaLophotrochozoa • flatworms, ribbon worms, mollusks, annelids, flatworms, ribbon worms, mollusks, annelids,

lophophorate phyla, rotifers lophophorate phyla, rotifers

• Ecdysozoa Ecdysozoa ((animals that molt)animals that molt)• nematodes and arthropodsnematodes and arthropods

3 Clades of Bilateral Animals3 Clades of Bilateral Animals

• LophotrochozoaLophotrochozoa

• EcdysozoaEcdysozoa

• DeuterostomiaDeuterostomia

Relationships Relationships Based on Based on

Molecular DataMolecular Data

Fig. 29-8a, p. 629

Parazoa EumetazoaRadiata Bilateria

Protostomia Deuterostomia

Lophotrochozoa Ecdysozoa

Ch

oan

ofl

agel

late

s

Po

rife

ra

Cn

ida

ria

Cte

no

ph

ora

Pla

tyh

elm

inth

es

Nem

erte

a

Mo

llu

sca

An

nel

ida

Lo

ph

op

ho

rate

ph

yla

Ro

tife

ra

Nem

ato

da

Tar

dig

rad

a

On

ych

op

ho

ra

Art

hro

po

da

Ech

ino

de

rmat

a

Hem

ich

ord

ata

Ch

ord

ata

Segmentation

Segmentation

Segmentation

Deuterostome pattern of development

Protostome pattern of development

Radial symmetry

Bilateral symmetry, three tissue layers, body cavity

TissuesMulticellularity


Fig. 29-8b, p. 629

Par

azo

a

Rad

iata

Ecd

yso

zoa

Lo

ph

otr

och

ozo

a

Deu

tero

sto

mia



• Molecular data indicate that bilateral Molecular data indicate that bilateral animals split into three major clades: animals split into three major clades: • two protostome groups—Lophotrochozoa two protostome groups—Lophotrochozoa

(such as flatworms, mollusks, and annelids) (such as flatworms, mollusks, and annelids) and Ecdysozoa (such as nematodes and and Ecdysozoa (such as nematodes and arthropods)—and deuterostomes arthropods)—and deuterostomes (echinoderms and chordates)(echinoderms and chordates)


• What are the distinguishing characteristics What are the distinguishing characteristics of phylum of phylum PoriferaPorifera??

PhylumPhylum PoriferaPorifera

• SpongesSponges• animals characterized by flagellate animals characterized by flagellate collar cells collar cells

(choanocytes)(choanocytes)

• The only members of the The only members of the ParazoaParazoa• sister group of sister group of EumetazoaEumetazoa

Sponge StructureSponge Structure

• Sponge bodySponge body• sac with tiny openings for water to entersac with tiny openings for water to enter• central cavity (central cavity (spongocoel)spongocoel)• open end (open end (osculumosculum) for water to exit) for water to exit

• Sponge cellsSponge cells• loosely associatedloosely associated• do not form true tissuesdo not form true tissues

Sponge StructureSponge Structure


Fig. 29-9a, p. 630

Parazoa

Po

rife

ra

Rad

iata

Lo

ph

otr

och

ozo

a

Ecd

yso

zoa

Deu

tero

sto

mia

Fig. 29-9b, p. 630

Osculum

SpongocoelIncurrent pores

Wat

er m

ove

men

t

Epidermal cell

Porocyte

Spicule

Microvillus

Flagellum

Amoeboid cell in mesohyl

Nucleus Collar cell

Collar


• Sponges (phylum Porifera) are Sponges (phylum Porifera) are characterized by collar cells and by loosely characterized by collar cells and by loosely associated cells that do not form true associated cells that do not form true tissuestissues

Insert “Body plan of a Insert “Body plan of a sponge”sponge”

sponge_body.swfsponge_body.swf

Learn more about sponge Learn more about sponge structure by clicking on the structure by clicking on the

figure in ThomsonNOW.figure in ThomsonNOW.


• What are the distinguishing characteristics What are the distinguishing characteristics of phylum of phylum CnidariaCnidaria??

• Describe four classes of this phylumDescribe four classes of this phylum

• Give examples of animals that belong to Give examples of animals that belong to each classeach class

PhylumPhylum Cnidaria 1Cnidaria 1

• Characterized byCharacterized by• radial symmetryradial symmetry• two tissue layerstwo tissue layers• cnidocytescnidocytes (cells containing (cells containing nematocystsnematocysts))

NematocystsNematocysts

Fig. 29-11b, p. 634

Cnidocyte

Nucleus

Thread

Capsule

Nematocyst (not discharged)

Cnidocil (trigger)

Thread

Nematocyst (discharged)

Insert “Nematocyst Insert “Nematocyst action”action”

nematocyst_v2.swfnematocyst_v2.swf

PhylumPhylum Cnidaria 2Cnidaria 2

• Gastrovascular cavityGastrovascular cavity • with single opening for mouth and anus with single opening for mouth and anus

• Nerve cellsNerve cells form irregular, nondirectional form irregular, nondirectional nerve netsnerve nets • connect sensory cells with contractile and connect sensory cells with contractile and

gland cellsgland cells

Cnidarian StructureCnidarian Structure

• HydraHydra

Fig. 29-12, p. 634

Tentacles

Cnidocytes (stinging cells)

1 mm Mouth

Egg (ovum)Bud

Gastrovascular cavity Ovary

EpidermisMesoglea

Gastrodermis

Cnidaria Life CycleCnidaria Life Cycle

• Sessile Sessile polyp polyp stagestage• form with dorsal mouth surrounded by form with dorsal mouth surrounded by

tentaclestentacles

• Free-swimming Free-swimming medusa medusa (jellyfish) stage(jellyfish) stage

Cnidaria Life CycleCnidaria Life Cycle

• ObeliaObelia

Fig. 29-13b, p. 635

1 Reproductive polyps produce medusae by budding asexually

Mouth MedusaeTentacle

Feeding polyp

2 Free-swimming medusae reproduce sexually.Medusa bud

Egg SpermReproductive polyp

Gastrovascular cavity

3 Zygote develops into ciliated planula larva.Planula

larva

Polyp colony4 Larva develops into

polyp that forms new colony.

5 Colony grows as new polyps bud and remain attached. Young

polyp colony

(b) Life cycle of Obelia.

4 Classes of4 Classes of Phylum CnidariaPhylum Cnidaria

1. Class1. Class Hydrozoa Hydrozoa (hydras, hydroids, (hydras, hydroids, Portuguese man-of-war)Portuguese man-of-war)• typically polypstypically polyps• may be solitary or colonial may be solitary or colonial

2. Class2. Class Scyphozoa Scyphozoa (jellyfish) (jellyfish)• generally medusaegenerally medusae

4 Classes of4 Classes of Phylum CnidariaPhylum Cnidaria

3. Class 3. Class CubozoaCubozoa (“box jellyfish”) (“box jellyfish”)• have complex eyes that form blurred imageshave complex eyes that form blurred images

4. Class 4. Class AnthozoaAnthozoa (sea anemones, corals) (sea anemones, corals)• polypspolyps• may be solitary or colonial may be solitary or colonial • differ from hydrozoans in organization of differ from hydrozoans in organization of

gastrovascular cavitygastrovascular cavity

CnidariansCnidarians

Fig. 29-10 (1), p. 633

Radiata

Par

azo

a

Cn

idar

ia

Cte

no

ph

ora

Lo

ph

otr

och

ozo

a

Ecd

yso

zoa

Deu

tero

sto

mia


Fig. 29-10a, p. 633

Mouth

Epidermis

Mesoglea

Gastrodermis


Class Hydrozoa (polyp)

Fig. 29-10b, p. 633

Mouth Mesoglea

GastrodermisEpidermis


Class Scyphozoa (medusa)

Fig. 29-10c, p. 633

Mouth

Epidermis

Mesoglea

Gastrodermis


Class Anthozoa (polyp)

Insert “Cnidarian body Insert “Cnidarian body plans”plans”

cnidarian_bodies.swfcnidarian_bodies.swf


• Members of phylum Cnidaria (hydras, Members of phylum Cnidaria (hydras, jellyfish, sea anemones) are characterized jellyfish, sea anemones) are characterized by radial symmetry, two tissue layers, and by radial symmetry, two tissue layers, and cnidocytes, cells that contain stinging cnidocytes, cells that contain stinging organellesorganelles

Insert “Cnidarian life Insert “Cnidarian life cycle”cycle”

obelia_life_cycle.swfobelia_life_cycle.swf

Learn more about cnidarian body Learn more about cnidarian body forms, nematocysts, and life forms, nematocysts, and life

cycles by clicking on the figures cycles by clicking on the figures in ThomsonNOW.in ThomsonNOW.


• What are the distinguishing characteristics What are the distinguishing characteristics of phylum of phylum CtenophoraCtenophora??

PhylumPhylum CtenophoraCtenophora

• Comb jelliesComb jellies• fragile, luminescent marine predatorsfragile, luminescent marine predators• biradial symmetrybiradial symmetry• eight rows of cilia that resemble combseight rows of cilia that resemble combs• tentacles with adhesive glue cellstentacles with adhesive glue cells

Comb JellyComb Jelly


• Members of phylum Ctenophora (comb Members of phylum Ctenophora (comb jellies) have biradial symmetry, two tissue jellies) have biradial symmetry, two tissue layers, eight rows of cilia, and tentacles layers, eight rows of cilia, and tentacles with adhesive glue cellswith adhesive glue cells

Documents

The Animal Kingdom: An Introduction to Animal Diversity Chapter 29