Animal Evolution (Learning Objectives)1 Review the characteristics of organisms of the Kingdom Animalia1. Review the characteristics of organisms of the Kingdom Animalia2. Recognize the evolution of animals as diploid multi-cellular aquatic

organisms from a colonial protist. 3 Summarize the highlights of animal evolution and the order of their3. Summarize the highlights of animal evolution and the order of their

appearance. Learn the names of the classification groupings that arose from successive adaptation with examples.

4 Learn the distinguishing features of each of the animal phylla and4. Learn the distinguishing features of each of the animal phylla and identify its representative organisms.

5. Summarize the highlights of evolution of land animals from their aquatic ancestors and the order of their appearanceaquatic ancestors and the order of their appearance.

6. Recognize parasitism as an integral part of animal evolution. Learn the names of parasites causing common diseases and relate them to their classification grouping and is evolutionary featuresclassification grouping and is evolutionary features.

7. Place any of the organisms learned in class or lab into its classification grouping , relate to others, and provide its evolutionary features.

8 O d i di t th d f th i th8. Order organisms according to the order of their appearance on earth.

Evolution of AnimalsEvolution of Animals

Animals are eukaryotic, multi-cellular, heterotrophic organisms that ingest theirheterotrophic organisms that ingest their

food

The ancestor of animals was probably aThe ancestor of animals was probably a colonial, flagellated protist whose cells

gradually became more specialized andgradually became more specialized and layered

Somaticcells

Digestivecavity

Reproductivecellscells

1 Colonial protist,an aggregateof identical cells

2 Hollow sphereof unspecializedcells (shown in

ti )

3 Beginning of cellspecialization(cross section)

4 Infolding(cross section)

5 Gastrula-like“proto-animal”(cross section)

cross section)

Animal DiversityE k ti Ki dEukaryotic Kingdom

Animalia– Body composition

• Multi-cellular evolving from a colonial protist ancestor• Later forms with organ systems, organs, and tissues

– Heterotrophicp• Some free living others parasitic

– Early forms are aquaticEarly forms are aquatic – Evolutionary adaptations led to evolution of land

animalsanimals

Spon

ges

Cni

daria

ns

Flat

wor

ms

Rou

nd w

orm

s

Mol

lusc

s

Ann

elid

s

Art

hrop

ods

Echi

node

rms

Cho

rdat

es

Segmentation

R

Mouth from Mouth from

E

Organ Systems(Coelom)

No Body Cavity Body Cavity

Mouth from First Embryonic

Opening

Mouth from Second Embryonic

Opening

Tube w/in Tube

Radial Symmetry Bilateral Symmetry

y y(No coelom)

y y(Pseudocoelom)

Sac Body Plan

Level of OrganizationMulticellular

Level of Organization

Invertebrates & Vertebrates

ges

ans

rms

ates

orm

s

uscs

elid

s

pods

des

Phylla (by

Spon

g

Cni

daria

Echi

node

r

Cho

rda

Flat

wo

Mol

lu

Ann

e

Art

hrop

Nem

atoPhylla (by

their common names)

Radial symmetryBilaterians

ProtostomesDeuterostomesPhylogenetic Tree of Animals

No true tissues True tissues

Bilateral symmetryRadial symmetry

Eumetazoans

Animals Mostly

invertebratesAncestral

colonial protist

invertebrates

Two major animal body forms: Early o ajo a a body o s a yInvertebrates and later Vertebrates

• Steps of animal evolutionF ti f ti– Formation of tissues

– Body made of three distinct layers of cells– Body symmetry: radial and bilateral– Bilateral organisms:

• Deuterostomes & protostomes

Classification Criteria for Animals

Level of OrganizationTissue organ organ systemsTissue, organ, organ systems

Body SymmetryNone- asymmetricNone asymmetricBilateralRadial

Body PlanSac with one openingT b ithi t b t iTube within a tube-two openings

Segmentation (with and without appendages)

KeyHaploid (n)Diploid (2n) Sperm

2

Meiosis EggZygote(fertilized egg)

1

3(fertilized egg)

Adult Eight-cell stage8

Diploid cells

MetamorphosisBlastula(cross section)

Digestive tract

4

EctodermLarva 5

Early gastrula(cross section)Future

mesodermLater gastrula(cross section)Internal sac

Endoderm6

7

Animal development may include a blastula, gastrula, and larval stage

Animals can be characterized by basicAnimals can be characterized by basic features of their “body plan”. They may vary in symmetrysymmetry.

Top Dorsal surface

AnteriorAnteriorend

Posterior end

Ventral surface

Bottom

Animals and digestive cavities

Incomplete gut (sac-like)radial symmetryradial symmetrybilateral symmetry

Complete gut- type 1Complete gut type 1 bodies without shellsbodies with shellsbodies with shellsbodies with segments

with exoskeletonComplete gut- type 2

hydraulic tube feetbodies with notochord

Sac like Sac likeTube: 2 openings Tube 2: openings

ges

ans

rms

ates

orm

s

uscs

elid

s

pods

desAnimal guts

Spon

g

Cni

daria

Echi

node

r

Cho

rda

Flat

wo

Mol

lu

Ann

e

Art

hrop

Nem

ato

Radial symmetryBilaterians

ProtostomesDeuterostomes

No true tissues True tissues

Bilateral symmetryRadial symmetry

Eumetazoans

Ancestralcolonial protist

INVERTEBRATESSponges have a relatively simple, porous body

Sponges are the simplest animals and have no true tissues

S filt f d f th t i th hSponges filter food from the water passing through the porous body

Cnidarians are radial animals with tentacles d ti i ll d t tiand stinging cells and true tissues

They have two body forms - Polyps, such as hydra - Medusae, the jellies

Hydra Jellyfish Sea anemone

Body covering

Tissue-filled region(from mesoderm)

Animal body cavity-coelom

(from ectoderm)

Flat worms- noneDigestive tract(from endoderm)

Flat worms none

Body covering(from ectoderm)

Muscle layer(from mesoderm)Round worms- pseudo Digestive tract(from endoderm)

Pseudocoelom

coelom

Body covering(from ectoderm)

Tissue layer

Coelom

Round worms- coelom ylining coelomand suspendinginternal organs(from mesoderm)Digestive tract

(from endoderm)

Flatworms are the simplest bilateral animalsFlatworms are bilateral animals that have:Flatworms are bilateral animals that have:- no body cavity - a sac-like gut- a simple nervous system- Free living & parasitic forms

G t l N dGastrovascularcavity

Nerve cords

Mouth

Eyespots

Bilateral symmetry

Nervoustissueclusters

Parasitic flatwormsTapeworms Cause diseasesParasitic flatworms

e.g. Flukes and tapeworms

commonly after eating raw or undercooked meat (beef and pork) orp

Flukes diseases

meat (beef and pork) or fish that contains the immature form of the

- sheep and cattle (fascioliasis)

tapeworm

- Human lung fluke disease (endemic

Units withreproductivestructures

0disease (endemic hemoptysis)

Scolex(anteriorend)

HooksSuckerriz

ed S

EM 8

0

)Sucker

Col

or

Parasites form a large proportion of the diversity of life on earthlife on earth-Have a complex lifecomplex life cycles with more thanmore than one host

R d (N d )Round worms (Nematodes)• have a pseudocoelom and a • complete digestive tract and are • covered by a protective cuticle.• usually microscopic and colorless.• some live free in moist soil, water, or in decaying

matter.• Parasitic forms cause diseases of plants and

animals.

Parasitic withFree-living

Parasitic- with complex life-cycle

Trichinella juvenileMuscle tissue

SEM

400

LM 3

50

Col

oriz

ed S

Mouth

Molluscs- have a distinct body plan• bilaterally symmetricalbilaterally symmetrical • a muscular foot, visceral mass, and a mantle which may

secrete a shell• well defined organ systems: circulatory respiratory and• well-defined organ systems: circulatory, respiratory, and

digestive with a rasping radulaVisceral massVisceral mass

Mantle Digestive

ReproductiveorgansHeart

CoelomKidney

Mantle

Radula Radula

Digestive tractShell

gtract

MantlecavityAnus

Mouth

MouthAnus

Gill

Nervecords

Foot

The largest group of molluscs includes the g g psnails and slugs

Another group of molluscs are the bivalves have shells divided into two halves. This includes clams, oysters, mussels, and scallops

Another group are adapted to be agile predators g p p g psuch as squids and octopuses

Annelids (Segmented worms) –S t ti id dd d bilit f i iSegmentation provides added mobility for swimming and burrowingEarthworms eat their way through soil and have aEarthworms eat their way through soil and have a closed circulatory system Segment wall

(partitionbetween

t )Anus Epidermis

Circular segments)

Segmentwall

muscle

LongitudinalExcretoryorganMucus-secreting

organBristles

Bristles

gmuscleDorsalvesselIntestine

Brain

Dorsalvessel

CoelomDigestivetract

Segmentwall

Nerve cordVentral vessel

Bristles Excretoryorgan

GiantAustralianearthworm

Mouth

a

Blood vesselsNerve cord

Pumping segmental vessels

The largest group of segmented wormsThe largest group of segmented worms search for prey on the seafloor or live in tubes and filter food particlesand filter food particles

Arthropods (Jointed legs) – segmented animals – jointed appendagesj pp g– exoskeleton

Extremely A t Thorax

Cephalothorax Abdomen

– Extremely diverse

Antennae(sensoryreception)

HeadThorax

SwimmingSwimmingappendages

Walking legs

Mouthparts (feeding)Pincer (defense)

Di th d i l dDiverse arthropods include:

- Millipedes and Centipedes- Horseshoe crabs- Arachnids such as spiders, scorpions,

mites, and ticks- Crustaceans- aquatic. Include crabs,

shrimps, and barnacles- Insects

00

A black widow spider (about1 cm wide) or

ized

SEM

90

A dust mite (about 420 µm long)A scorpion (about 8 cm long)

)

Col

o

Echinoderms have spiny skin, an d k l t d t l tendoskeleton, and a water vascular system

for movement- organisms such as sea stars and sea urchins- radially symmetrical as adults

Tube foot Tube foot

Spine

The water vascular system has suction cup–like tube feet used for respiration and locomotion

Anus

SSpines

Stomach

Tube feet

Canals

Phylum Chordata, is distinguished by four f tfeatures

• A dorsal hollow nerve cordA tiff t h d• A stiff notochord

• Pharyngeal slits• A muscular post-anal tail• A muscular post-anal tail• Includes invertebrates and verebrates

ChordatesCraniates

VertebratesJawed vertebrates

Tetrapodses TetrapodsAmniotes

Milknica

tes

ance

lets

agfis

hes

mpr

eys

arks

, ray

s

inne

d fis

he

obe-

fins

mph

ibia

ns

Rep

tiles

amm

als

Milk

Amniotic egg

Legs

Tu La Ha

La Sha

Ray

-fi Lo

Am R M

a

Lobed fins

Lungs or lung derivatives

Jaws

Vertebral column

Head

Brain

Ch d tInvertebrates

Ancestral chordate Chordates

The simplest chordates are tunicates andThe simplest chordates are tunicates and lancelets

Marine invertebrates with pharyngeal slits for p y gsuspension feeding

Excurrent Post-anal tailExcurrentsiphon

Dorsal, hollownerve cord

Muscle

Head

MouthNotochord

Mouth

Pharyngealslits

segments

Notochord

PharynxPharyngealslitsDigestive tract

Water exit Post-anal

Dorsal,hollownerve cord

Ad ltSegmentalmuscles Anus

tailAdult(about 3 cm high) Larva

Jawless fish- Lampreys are vertebrates thatJawless fish Lampreys are vertebrates that lack hinged jaws and paired fins

Sharks and rays have a flexible skeleton made of ycartilageUncovered gills

Bony Fishes (ray-finned fishes)k l t i f d ith h d t i f- skeleton reinforced with a hard matrix of

calcium phosphate- Operculi that move water over the gillsOperculi that move water over the gills- A buoyant swim bladder

Bony skeleton

Gills

Bony skeletonDorsal fin

Anal finSwim bladder

HeartPectoral finOperculum

Pelvic fin

Rainbow troutRainbow trout,a ray-fin

L b fi fi h h l fiLobe-fins fishes have muscular fins supported by bones

Amphibians are tetrapods—vertebrates with two pairs of limbs allowing movement on land

Bonessupportingsupportinggills

Tetrapodlimbskeleton

Most amphibian reproduce in waterFertilization and embryos and larval development

take place in waterE l f t d dExamples are frogs, toads, and

salamanders

Reptiles are amniotes—tetrapods with a terrestrially adapted eggadapted egg

Terrestrial adaptations of reptiles includeWaterproof scales pInternal fertilizationshelled, amniotic egg

Dinosaurs, the most diverse reptiles to inhabit land– Included some of the largest animals ever to inhabit land– May have been endothermic, producing their own body

heatheat

Birds are feathered reptiles with adaptations for flightflightBirds evolved from a lineage of small, two-legged ectothermic dinosaurs called theropods.ectothermic dinosaurs called theropods.Living reptiles other than birds are ectothermic

Wing clawT th(like dinosaur) Teeth(like dinosaur)

Long tail withFeathers

gmany vertebrae

(like dinosaur)

Birds have wings, feathers, endothermic metabolism and many other adaptations relatedmetabolism, and many other adaptations related to flight

Mammals are endothermic amniotes with- Hair for temperature insulation- Internal fertilizationInternal fertilization- Mammary glands for milk production

Two groups of mammals 1. Marsupials- Kangaroos2. Eutherians, placental mammals

The embryos of marsupials are:nurtured within the uterus- nurtured within the uterus

- leave the uterus before completing development-complete development attached-complete development attached to the mother’s nipple, usually inside a pouchinside a pouch

Eutherians, placental mammals, complete development before birthdevelopment before birth