Introduction to Animal Introduction to Animal DiversityDiversityPacket #76Packet #76Chapter #32Chapter #32

Animal DiversityAnimal Diversity

Biologists have identified 1.3 million living Biologists have identified 1.3 million living species if animals.species if animals.

Estimates put the range much higherEstimates put the range much higher 10 – 200 million10 – 200 million

Evolutionists believe that the Evolutionists believe that the chanoflagellates, a colonial flagellated protist, chanoflagellates, a colonial flagellated protist, was the start of Kingdom Animalia.was the start of Kingdom Animalia.

Characteristics Most Common to Characteristics Most Common to AnimalsAnimals

EukaryoticEukaryotic

MulticellularMulticellular

HeterotrophicHeterotrophic

Animals use enzymes to digest their food Animals use enzymes to digest their food after they have ingested it.after they have ingested it.

Stores energy as fat (long term) or as Stores energy as fat (long term) or as glycogen (short term)glycogen (short term)

Reproduction in AnimalsReproduction in Animals

Reproduction—The Reproduction—The ObviousObvious

Most animals reproduce sexually and have a Most animals reproduce sexually and have a diploid stage that is dominant in the life cycle.diploid stage that is dominant in the life cycle.

Sperm and egg unite to form a zygoteSperm and egg unite to form a zygote Zygote undergoes cleavageZygote undergoes cleavage Multiple cell divisions result in the development Multiple cell divisions result in the development

of a hollow ball of cellsof a hollow ball of cells BlastulaBlastula

Blastula undergoes gastrulation.Blastula undergoes gastrulation. Embryonic tissues are formedEmbryonic tissues are formed Developmental stage is called the gastrula.Developmental stage is called the gastrula.

Reproduction—The Sometimes Reproduction—The Sometimes Not So ObviousNot So Obvious

Some animals develop directly into adultsSome animals develop directly into adults After transient stages of maturationAfter transient stages of maturation

However, life cycle of many animals include However, life cycle of many animals include larval stages.larval stages. LarvaLarva

Sexually immature form of an adultSexually immature form of an adult Morphologically distinctMorphologically distinct Usually eats different foodUsually eats different food Inhabits different areas than the adultInhabits different areas than the adult Must undergo metamorphosis to become an adultMust undergo metamorphosis to become an adult

Developmental Genes Across Developmental Genes Across Kingdom AnimaliaKingdom Animalia

Animals share a unique homeoboxAnimals share a unique homeobox Family of genesFamily of genes

Hox genesHox genes The number of hox genes is correlated with the The number of hox genes is correlated with the

complexity of the animal’s anatomy.complexity of the animal’s anatomy.

Categorizing Kingdom Categorizing Kingdom AnimaliaAnimalia

Animals are classified on major features of Animals are classified on major features of animal body plans.animal body plans. SymmetrySymmetry Tissue ComplexityTissue Complexity CephalizationCephalization Body CavitiesBody Cavities

Body PlansBody PlansSymmetrySymmetry

IntroductionIntroduction

There are two types of There are two types of symmetrysymmetry Radial SymmetryRadial Symmetry Bilateral SymmetryBilateral Symmetry

SymmetrySymmetry

Radial SymmetryRadial Symmetry Describes how the parts Describes how the parts

of an animal radiate of an animal radiate from the center.from the center. Any imaginary slice Any imaginary slice

through the central through the central axis divides the axis divides the animal into mirror animal into mirror images.images.

Sea anemones have a Sea anemones have a top (oral, mouth) side top (oral, mouth) side and a bottom (aboral) and a bottom (aboral) side.side.

Symmetry IISymmetry II

Bilateral SymmetryBilateral Symmetry Describes a two sided Describes a two sided

body plan.body plan. Animal has a left Animal has a left

side and right sideside and right side Imaginary slice can Imaginary slice can

only be placed in one only be placed in one location in order to location in order to divide the animal divide the animal mirror images.mirror images.

Lobster has a dorsal Lobster has a dorsal (top) side, a ventral (top) side, a ventral (bottom) side, a left (bottom) side, a left and right side, an and right side, an anterior (head) with a anterior (head) with a mouth and a posterior mouth and a posterior (tail) end.(tail) end.

Symmetry IIISymmetry III

Animals can be categorized according to the Animals can be categorized according to the symmetry of their bodies or lack of it.symmetry of their bodies or lack of it.

Symmetry Reflects LifestyleSymmetry Reflects Lifestyle Radial animals are sessile or planktonicRadial animals are sessile or planktonic Bilaterial animals more actively from one place Bilaterial animals more actively from one place

to anotherto another The nervous system enables these organisms to The nervous system enables these organisms to

move.move.

TissueTissue

Tissue ITissue I

As a young embryo As a young embryo develops, embryonic develops, embryonic tissue, called germ tissue, called germ layers, are produced via layers, are produced via gastrulationgastrulation..

There are three germ There are three germ layerslayers EctodermEctoderm EndodermEndoderm MesodermMesoderm

Tissue IITissue II

EctodermEctoderm Outer layerOuter layer Gives rise to the body Gives rise to the body

covering and the covering and the nervous systemnervous system

EndodermEndoderm Inner layerInner layer Gives rise to the lining Gives rise to the lining

of the gut (archenteron) of the gut (archenteron) and other digestive and other digestive organsorgans

MesodermMesoderm Middle layerMiddle layer Gives rise to most other Gives rise to most other

body structures.body structures. Including muscleIncluding muscle

Diploblastic vs. Diploblastic vs. TriploblasticTriploblastic

DiploblasticDiploblastic Animals with only two Animals with only two

layerslayers Ectoderm and Ectoderm and

EndodermEndoderm JelliesJellies CoralsCorals Comb jelliesComb jellies

TriploblasticTriploblastic Animals with all three Animals with all three

layerslayers Include all bilaterally Include all bilaterally

symmetric animals.symmetric animals.

Triploblastic Animals & Triploblastic Animals & Body CavitiesBody Cavities

Functions of Body Functions of Body CavitiesCavities

Provides protection to internal organsProvides protection to internal organs

Allow organs to grow and move Allow organs to grow and move independently of the outer body wall.independently of the outer body wall.

Body Cavity IBody Cavity I

TriploblasticTriploblastic animals have animals have traditionally been classified astraditionally been classified as Acoelomates Acoelomates [ey-see-luh-[ey-see-luh-

meyt]meyt] No body cavityNo body cavity Lack a coelom. Lack a coelom. [see-luhm][see-luhm]

Pseudocoelomate Pseudocoelomate [soo-doh-[soo-doh-see-luh-meyt, -si-loh-mit]see-luh-meyt, -si-loh-mit] Body cavity not completely Body cavity not completely

lined with mesodermlined with mesoderm Body cavity formed from Body cavity formed from

the the blastocoel.blastocoel. CoelomateCoelomate

True coelomTrue coelom Body cavity completely Body cavity completely

lined with mesoderm.lined with mesoderm. Cushions the internal Cushions the internal

organs and protects them.organs and protects them.

Formation of the Formation of the Coelom [see-luhm]Coelom [see-luhm]

Coeloms can be divided Coeloms can be divided into two categories based into two categories based on how it is developed.on how it is developed.

During gastrulation, During gastrulation, developing digestive tube developing digestive tube forms the archenteron.forms the archenteron.

ProtostomesProtostomes Development of the Development of the

coelom forms from splits coelom forms from splits in the mesodermin the mesoderm Schizocoelous Schizocoelous

DevelopmentDevelopment

DeuterostomesDeuterostomes Development of the Development of the

coelom forms from coelom forms from outpocketing of the outpocketing of the mesodermal tissue of the mesodermal tissue of the archenteron.archenteron. Enterocoelous Enterocoelous

DevelopmentDevelopment

The CoelomatesThe Coelomates

Introduction IIntroduction I

ProtostomiaProtostomia MollusksMollusks AnnelidsAnnelids ArthropodsArthropods

DeuterostomiaDeuterostomia EnchinodermsEnchinoderms ChordatesChordates

ProtostomesProtostomes

Blastopore develops into Blastopore develops into the mouththe mouth

Undergo spiral and Undergo spiral and determinate cleavagedeterminate cleavage Spiral cleavageSpiral cleavage

Describes how the Describes how the planes of cell division planes of cell division are diagonal to the are diagonal to the vertical axis of the vertical axis of the embryo.embryo. Smaller cells lie in the Smaller cells lie in the

grooves between larger, grooves between larger, underlying cellsunderlying cells

Determinate cleavageDeterminate cleavage Indicates that the Indicates that the

developmental fate of developmental fate of each embryonic cell is each embryonic cell is determined at determined at fertilization.fertilization. If cell is isolated it will If cell is isolated it will

form an inviable embryo.form an inviable embryo.

DeuterostomesDeuterostomes

Blastopore typically Blastopore typically becomes the anus.becomes the anus.

Undergo radial and Undergo radial and indeterminate cleavage.indeterminate cleavage. Radial cleavageRadial cleavage

Cleavage planes are Cleavage planes are either parallel or either parallel or perpendicular to the perpendicular to the vertical axis of the eggvertical axis of the egg

Indeterminate cleavageIndeterminate cleavage Each cell produced by Each cell produced by

early cleavage divisions early cleavage divisions has the capacity to has the capacity to develop into a complete develop into a complete embryo.embryo.

Protostomes vs. Protostomes vs. DeuterostomesDeuterostomes

ReviewReview

SymmetrySymmetry

TissueTissue

Germ Layers Germ Layers Body Body CavityCavity

Body CavityBody Cavity