Chapters 25 and 26
 Objectives
 List the characteristics
that all animals share.
 Differentiate between
invertebrates and
chordates.
 Describe some features
of animal body plans.
 Heterotrophic
 Multi-cellular
 Eukaryotic
 No cell walls
 Invertebrates – 95% of animals
 Lack a backbone
 Examples:
Jellyfish
Seastar
Worm
Insect
 Chordates – 5% of animals
 Characteristics:
1. Dorsal, hollow nerve chord
2. Notochord

Long supporting rod running length of body
3. Tail extending past anus
4. Pharyngeal pouches

Paired structures in throat region
 Most are vertebrates (animals with backbones)
 Examples: fish, amphibians, reptiles, birds,
mammals
 List the characteristics all animals have
 Multicellular, heterotrophs, eukaryotes, no cell
walls
 What 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
 Cells
 Tissues
 Organs
 Organ systems
 Organism
 Asymmetry – no symmetry
 Radial symmetry – body parts
extend from central point
 Bilateral symmetry – two sides
(mirror image)
 Anterior – front
 Posterior – back
 Dorsal – upper
 Ventral - lower
 Cells of most animal embryos differentiate
into:
 Endoderm – innermost layer
 Mesoderm – middle layer
 Ectoderm – outermost layer
 Body cavity – fluid filled space between
digestive tract and body wall
 Acoelomate – no body cavity
 Pseudocoelomate – body cavity partially lined
with mesoderm
 Coelomate – body cavity lined with mesoderm
 Zygote – fertilized egg
 Develops into blastula
(hollow ball of cells)
 Blastopore – single
opening to outside
formed as blastula
folds inward
 Protostome –organism in which blastopore
becomes mouth
 Deuterostome –blastopore becomes anus
 List the levels of organization
 Cells  Tissues  Organs  Organ systems
 Organisms
 What type of symmetry do each of the
following have?
Radial
Bilateral
Asymmetry
Radial
Identify the sides of the animal that are labeled:
dorsal
ventral
anterior
posterior
 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
 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
 Objectives
 Describe characteristics of
invertebrate phyla.
 “Pore-bearer”
 Ex. Sponges
 No tissues or organ
systems
 Asymmetrical
 Filter feeders
 “Nettle” or “Stinger”
 Ex. Hydras, Jellyfish,
Sea anemones, Corals
 Cells organized into
tissues
 Radial symmetry
 Feed by stinging prey
with nematocysts,
mouth 
gastrovascular cavity
 Arthropods- “Jointed
foot”
 Ex. Insects,
crustaceans, spiders
 Segmented body,
exoskeleton of chitin,
jointed appendages
 Ex. pinworms
 Bilateral symmetry
 Tissue layers
 Pseudocoelomate
 Digestive system with
mouth and anus
 Molt (shed skin) as
they grow
 Ex. planarians,
flukes, tapeworms
 Bilateral symmetry
 Three tissue layers
 Acoelomate
 Ex. earthworms, leeches,
bristleworms
 Bilateral symmetry
 Tissue layers
 Coelomate
 Digestion- mouth
and anus, pharynx
 Circulation- closed
system (blood
contained in vessels)
 Respiration- some
gills, skin
 Excretion- Nephridia,
anus
 Nervous- brain and
nerve cords
 Reproduction Sexual: (most),
separate sexes,
hermaphrodites
 Mollusks
 Ex. Gastropods




(snails), Bivalves
(clams), Cephalopods
(squid)
Internal or external
shell
Bilateral symmetry
Tissue layers
Coelomate
 Echinoderms- “Spiny




skin”
Ex. Sea Stars, Sea
Urchins, Sand Dollars
Internal skeleton
Water vascular
system (tube feet)
Radial symmetry
 Objectives
 Describe characteristics of chordate phyla.
 Two invertebrate subphyla:
 Cephalochordata:
 Urochordata:
lancelets
tunicates
 No true jaws or teeth
 Lack vertebrae
 Skeleton made of cartilage
 Ex. Lampreys, hagfish
 Skeleton made of cartilage
 Paired fins
 Most have tooth-like scales
 Ex. Sharks, rays, skates
 Skeleton of true bone
 Paired fins, scales, gills
 Swim bladder
 Ex. Perch, bass, flounder
 Means “double life”
 Young: live in water and breathe with
gills
 Adult: live on land and breathe with
lungs and skin
 Undergo metamorphosis
 Dramatic change in body form
 Moist skin with mucous glands
 Lack scales and claws
 Ex. Frogs, toads, newts,
salamanders
 Digestive/Excretory:
 Developed: stomach, intestines, etc.
 Nervous:
 Developed: large eyesgreat sight
 Circulatory:
 Closed circulatory system
 Three chamber heart
 Reproductive:
 Most lay eggs without shells in water
 External Fertilization
 Respiratory:
 Gills when immature, lungs and skin when mature
(skin must stay moist to function)
 Vertebrates with lungs
 Scaly skin
 Leathery shelled amniotic eggs
 Ex. Lizards, snakes, turtles,
crocodiles, dinosaurs
 Warm-blooded
 Feathers
 Strong light-weight bones
 Hard-shelled amniotic eggs
 Two scaly legs and wings as
fore-limbs
 Ex. Hawk, eagle, penguin,
ostrich, hummingbird, robin
 Warm-blooded
 Feed young with milk from




mammary glands
Hair or fur
Breathe air
Four-chamber heart
Many groups of mammals Insect-eating, Water-dwelling,
Hoofed, Gnawing, etc.
 Monotremes
 Egg-laying mammals
 Ex. Platypus
 Marsupials
 Give birth to under-developed young
 Young develop in the pouch of the mother
 Ex. Kangaroo, koalas, possum
 Placental mammals:
 Give birth to young that have developed in
the mother’s body
 Ex. Humans, Dogs, Mice