Chapters 25 and 26

ANIMALS

ObjectivesList the

characteristics that all animals share.

Differentiate between invertebrates and chordates.

Describe some features of animal body plans.

Chapter 25.1 and 25.2

Heterotrophic

Multi-cellular

Eukaryotic

No cell walls

Characteristics of Animals

Invertebrates – 95% of animalsLack a backboneExamples:

Types of Animals

Seastar Worm

Jellyfish

Insect

Chordates – 5% of animalsCharacteristics:

1. Dorsal, hollow nerve chord2. Notochord

Long supporting rod running length of body3. Tail extending past anus4. Pharyngeal pouches

Paired structures in throat regionMost are vertebrates (animals with

backbones)Examples: fish, amphibians, reptiles, birds,

mammals

Types of Animals

List the characteristics all animals haveMulticellular, heterotrophs, eukaryotes,

no cell wallsWhat characteristic do all invertebrates

share?No backbone

What characteristics do all chordates have sometime in their life cycle?Hollow nerve cord, notochord, postanal

tail, pharyngeal pouches

Check-in

Cells

Tissues

Organs

Organ systems

Organism

Levels of Organization

Asymmetry – no symmetryRadial symmetry – body parts

extend from central pointBilateral symmetry – two

sides (mirror image)Anterior – frontPosterior – backDorsal – upperVentral - lower

Types of Body Symmetry

Cells of most animal embryos differentiate into:Endoderm – innermost layerMesoderm – middle layerEctoderm – outermost layer

Differentiation of Germ Layers

Body cavity – fluid filled space between digestive tract and body wallAcoelomate – no body cavityPseudocoelomate – body cavity partially

lined with mesodermCoelomate – body cavity lined with

mesoderm

Formation of a Body Cavity

Zygote – fertilized egg

Develops into blastula (hollow ball of cells)

Blastopore – single opening to outside formed as blastula folds inward

Embryological Development

Protostome –organism in which blastopore becomes mouth

Deuterostome –blastopore becomes anus

List the levels of organizationCells Tissues Organs Organ

systems OrganismsWhat type of symmetry do each of

the following have?

Check-in

Radial Bilateral Asymmetry Radial

Check-inIdentify the sides of the animal that are

labeled:

posterior

ventral

anterior

dorsal

What germ layer is the outermost layer?Ectoderm

What germ layer makes up the linings of the digestive tract and respiratory system?Endoderm

If an organism has a body cavity partially lined with mesoderm, what is it called?Pseudocoelomate

Check-in

What is a fertilized egg called?Zygote

Organism in which blastopore becomes anus:Deuterostome

What is an organism with a body cavity partially lined with mesoderm called?Pseudocoelomate

Check-in

ObjectivesDescribe characteristics

of invertebrate phyla.

Chapter 26.1

Cladogram of Nonchordate Invertebrates

Phylum Porifera“Pore-bearer”Ex. SpongesNo tissues or

organ systemsAsymmetricalFilter feeders

Phylum Cnidaria“Nettle” or “Stinger”Ex. Hydras, Jellyfish,

Sea anemones, Corals

Cells organized into tissues

Radial symmetryFeed by stinging prey

with nematocysts, mouth gastrovascular cavity

Phylum ArthropodaArthropods-

“Jointed foot”Ex. Insects,

crustaceans, spiders

Segmented body, exoskeleton of chitin, jointed appendages

Nematoda - RoundwormsEx. pinwormsBilateral

symmetryTissue layersPseudocoelomateDigestive system

with mouth and anus

Molt (shed skin) as they grow

Platyhelminthes - FlatwormsEx. planarians,

flukes, tapewormsBilateral

symmetryThree tissue

layersAcoelomate

Annelida – Segmented wormsEx. earthworms,

leeches, bristleworms

Bilateral symmetryTissue layersCoelomate

Annelida SystemsDigestion- mouth

and anus, pharynxCirculation-

closed system (blood contained in vessels)

Respiration- some gills, skin

Excretion- Nephridia, anus

Nervous- brain and nerve cords

Reproduction-Sexual: (most),

separate sexes, hermaphrodites

Phylum MolluscaMollusksEx. Gastropods

(snails), Bivalves (clams), Cephalopods (squid)

Internal or external shell

Bilateral symmetryTissue layersCoelomate

Phylum EchinodermataEchinoderms-

“Spiny skin”Ex. Sea Stars, Sea

Urchins, Sand Dollars

Internal skeletonWater vascular

system (tube feet)Radial symmetry

ObjectivesDescribe characteristics of chordate

phyla.

Chapter 26.2

Cladogram of Chordates

Nonvertebrate ChordatesTwo

invertebrateUrochordata:

tunicates

Cephalochordata: lancelets

subphyla:

No true jaws or teethLack vertebraeSkeleton made of cartilageEx. Lampreys, hagfish

Jawless Fishes

Skeleton made of cartilagePaired finsMost have tooth-like scalesEx. Sharks, rays, skates

Cartilaginous Fish

Skeleton of true bonePaired fins, scales, gillsSwim bladderEx. Perch, bass, flounder

Bony Fish

Means “double life”Young: live in water and breathe

with gillsAdult: live on land and breathe

with lungs and skinUndergo metamorphosis

Dramatic change in body formMoist skin with mucous glandsLack scales and clawsEx. Frogs, toads, newts,

salamanders

Amphibians

Digestive/Excretory:Developed: stomach, intestines, etc.

Nervous:Developed: large eyesgreat sight

Circulatory:Closed circulatory systemThree chamber heart

Reproductive:Most lay eggs without shells in waterExternal Fertilization

Respiratory:Gills when immature, lungs and skin when

mature (skin must stay moist to function)

Amphibian Systems

Vertebrates with lungsScaly skinLeathery shelled amniotic

eggsEx. Lizards, snakes,

turtles, crocodiles, dinosaurs

Reptiles

Warm-bloodedFeathersStrong light-weight bonesHard-shelled amniotic

eggsTwo scaly legs and wings

as fore-limbsEx. Hawk, eagle, penguin,

ostrich, hummingbird, robin

Birds

Warm-bloodedFeed young with milk from

mammary glandsHair or furBreathe airFour-chamber heartMany groups of mammals-

Insect-eating, Water-dwelling, Hoofed, Gnawing, etc.

Mammals

MonotremesEgg-laying mammalsEx. Platypus

MarsupialsGive birth to under-developed youngYoung develop in the pouch of the

motherEx. Kangaroo, koalas, possum

Placental mammals:Give birth to young that have

developed in the mother’s bodyEx. Humans, Dogs, Mice

Groups of Mammals