Introduction to Animals

Section 2 – Animal Kingdom

DomainBacteria

DomainArchaea

DomainEukarya

Common ancestor

Introduction to Animals

Section 2 – Animal Kingdom

DomainBacteria

DomainArchaea

DomainEukarya

Common ancestor

Animal Characteristics • Heterotrophs

– must ingest others for nutrients• Multicellular

– complex bodies• No cell walls

– allows active movement• Sexual reproduction

– no alternation of generations– no haploid gametophyte

PoriferaCnidaria

Platyhelminthes

sponges jellyfish flatworms roundworms

NematodaMollusca Arthropoda Chordata

Annelida Echinoderm

mollusks

multicellularity

Ancestral Protist

tissues

bilateral symmetry

body cavity

segmentation

Animal Evolution

coelom

starfish vertebrates

endoskeleton

segmentedworms

insectsspiders

backbone

3 GERM layers ectoderm mesoderm endoderm

Body CavityHow much is the digestive tract separated from the rest of the body?

ectoderm

ectodermmesodermendoderm

ectodermmesoderm

endoderm

mesodermendoderm

acoelomate

pseudocoelomate

coelomate

coelom cavity

pseudocoel

Invertebrate: Porifera• Sponges

– Diploblastic (two germ layers)– no distinct tissues or organs

• do have specialized cells

– no symmetry– sessile (as adults)

food taken into each cell by endocytosis

Invertebrate: Cnidaria• Jellyfish, hydra, sea anemone, coral

– Diploblastic (two germ layers)– tissues, but no organs– radial symmetry– predators

• tentacles surround gut opening

• GASTROVASCULAR cavity• extracellular digestion

– release enzymes into gut cavity

Invertebrate: Platyhelminthes

ectoderm

mesodermendoderm

• Flatworms– Triploblastic (3 germ layers)– Acoelom– Fluke, tapeworm, Planaria– few parasitic– bilaterally symmetrical

• allows high level of specialization within parts of the body

• Most have one opening (GASTROVASCULAR CAVITY)

Invertebrate: Nematoda• Roundworms

– Triploblastic– Pseudocoelom– bilaterally symmetrical– have both mouth & anus

• well-developed digestive system– many are parasitic

• hookworm• pinworm

Invertebrate: Mollusca• Mollusks

– clams, snails, squid– bilaterally symmetrical (with exceptions)

– soft bodies, mostly protected by hard shells– true coelom

Invertebrate: Annelida• Segmented worms

– earthworms, leeches– segments are not specialized– bilaterally symmetrical– true coelom fan worm leech

Invertebrate: Arthropoda• Spiders, insects, crustaceans

– most successful animal phylum– bilaterally symmetrical– segmented

• allows jointed appendages– exoskeleton

• chitin + protein

Arthropod groups

insects6 legs, 3 body parts

crustaceansgills, 2 pairs antennaecrab, lobster, barnacles, shrimp

arachnids8 legs, 2 body partsspiders, ticks, scorpions

Invertebrate: Echinodermata• Starfish, sea urchins, sea cucumber

– Adults - radially symmetrical – spiny exoskeleton– Water vascular system

Invertebrate quick check…

• Which group includes snails, clams, and squid?• Which group is the sponges?• Which are the flatworms?

…segmented worms?…roundworms?

• Which group has jointed appendages & an exoskeleton?

• Which two groups are radially symmetrical?• Which group has no symmetry?

Invertebrates: Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata

• Vertebrates– fish, amphibians, reptiles, birds, mammals– internal bony skeleton

• backbone encasing spinal column

• skull-encased brain

postanaltail notochord

hollow dorsalnerve cord

pharyngealpouches

Chordata

becomes brain & spinal cord

becomes vertebrae

becomes gills or Eustachian tube

becomes tail or tailbone

Vertebrates: Fishsalmon, trout, sharks

• Characteristics – body structure

• bony OR cartilaginous skeleton• jaws & paired appendages (fins)• scales

– body function• gills for gas exchange• two-chambered heart;

single loop blood circulation• ectotherms

– reproduction• external fertilization• external development in

aquatic egg

gills

body

lung

buccalcavity

glottisclosed

Vertebrates: Amphibian• Characteristics

– body structure• legs (tetrapods)• moist skin

– body function• lungs (positive pressure) &

diffusion through skin for gas exchange• three-chambered heart/2 loops • ectotherms

– reproduction• external fertilization• external development in aquatic egg• metamorphosis (tadpole to adult)

frogssalamanders toads

Vertebrates: Reptilesdinosaurs, turtles lizards, snakesalligators, crocodile

embryoleatheryshell

chorion

allantoisyolk sac

amnion

• Characteristics – body structure

• dry skin, scales, armor– body function

• lungs for gas exchange• thoracic breathing; negative pressure• three-chambered heart/2 loops• ectotherms • excrete uric acid

– reproduction• internal fertilization• external development in amniotic egg

Vertebrates: Birds• Characteristics

– body structure• feathers & wings• thin, hollow bone;

flight skeleton– body function

• very efficient lungs & air sacs• four-chambered heart/2 loops• endotherms• excrete uric acid

– reproduction• internal fertilization• external development in amniotic egg

finches, hawk ostrich, turkey

trachea

anteriorair sacs

lung

posteriorair sacs

Vertebrates: Mammals• Characteristics

– body structure• hair• specialized teeth

– body function• lungs, diaphragm; negative pressure• four-chambered heart/2 loops• endotherms

– reproduction• internal fertilization• internal development in uterus

– nourishment through placenta• birth live young• mammary glands make milk

mice, ferret elephants, batswhales, humans

musclescontract

diaphragmcontracts

Vertebrates: Mammals• Sub-groups

– monotremes• egg-laying mammals• duckbilled platypus, echidna

– marsupials• pouched mammals• short-lived placenta• koala, kangaroo, opossum

– placental• true placenta• shrews, bats, whales, humans

Vertebrate quick check…• Which vertebrates lay eggs with shells?• Which vertebrates are covered with scales?• What adaptations do birds have for flying?• What kind of symmetry do all vertebrates have?• Which vertebrates are ectothermic and which are

endothermic• Why must amphibians live near water?• What reproductive adaptations made mammals very

successful?• What characteristics distinguish the 3 sub-groups of

mammals?