1. ANIMALS
Chapters 25 and 26

2. Chapter 25.1 and 25.2 Objectives
List the characteristics that all animals share.
Differentiate between invertebrates and chordates.
Describe some features of animal body plans.

3. Characteristics of Animals
Heterotrophic
Multi-cellular
Eukaryotic
No cell walls
Heterotrophic – obtain nutrients and energy by eating other organisms
Eukaryotic – cells have a nucleus and membrane-bound organelles

4. Types of Animals Invertebrates – 95% of animals Lack a backbone
Examples:
Jellyfish
Seastar
Worm
Insect

5. Types of Animals Chordates – 5% of animals Characteristics:
Dorsal, hollow nerve chord
Notochord
Long supporting rod running length of body
Tail extending past anus
Pharyngeal pouches
Paired structures in throat region
Most are vertebrates (animals with backbones)
Examples: fish, amphibians, reptiles, birds, mammals
All chordates exhibit four characteristics at some point in their lives:
1. hollow nerve cord that runs along the dorsal (back) part of the body; nerves branch from this nerve cord
2. notochord – long supporting rod that runs length of body just under nerve cord; most chordates have a notochord only when they are embryos
3. postanal tail – tail that extends past anus (at some point in life)
4. pharyngeal pouches – paired structures in throat region (aka pharynx) – in fish, slits develop that connect the pouches to the outside of the body (may develop into gills for gas exchange)
Most chordates are vertebrates (except for few odd aquatic animals known an invertebrate chordates)

6. Check-in 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

7. Levels of Organization
Cells
Tissues
Organs
Organ systems
Organism
Next 5 slides describe some features of animal body plans: levels of organization, body symmetry, differentiation of germ layers, formation of body cavities, and patterns of embryological development.

8. Types of Body Symmetry 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
Three types of symmetry that animals can have

9. Differentiation of Germ Layers
Cells of most animal embryos differentiate into:
Endoderm – innermost layer
Mesoderm – middle layer
Ectoderm – outermost layer
Endoderm – linings of digestive tract and much of respiratory system
Mesoderm – muscles; much of circulatory, respiratory, and excretory systems
Ectoderm – sense organs, nerves, outer layer of skin

10. Formation of a Body Cavity
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
Body cavity provides space in which internal organs can be suspended, and room for these organs to grow
ex. Your stomach and digestive organs are suspended in your body cavity

11. Embryological Development
Zygote – fertilized egg
Develops into blastula (hollow ball of cells)
Blastopore – single opening to outside formed as blastula folds inward
As zygote develops, becomes a blastula (hollow ball of cells like inflated balloon)
As blastula develops, it folds in on itself (like holding balloon and pushing thumbs in toward center)
Blatula becomes elongated structure with tube running in center (becomes digestive tract)
Digestive tract has only one opening at first (blastopore)
Efficient digestive sys needs two openings (mouth and anus)
Protostome –organism in which blastopore becomes mouth
Deuterostome –blastopore becomes anus

12. Check-in 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

13. Check-in Identify the sides of the animal that are labeled: dorsal
ventral
posterior
anterior

14. Check-in 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

15. 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

16. Chapter 26.1
Objectives
Describe characteristics of invertebrate phyla.

17. Cladogram of Nonchordate Invertebrates
Cladogram – shows evolutionary relationships between organisms
Nodes (red circles) – show where important traits evolved in the course of evolution

18. Phylum Porifera “Pore-bearer” Ex. Sponges No tissues or organ systems
Asymmetrical
Filter feeders
Simplest animals

19. Phylum Cnidaria “Nettle” or “Stinger”
Ex. Hydras, Jellyfish, Sea anemones, Corals
Cells organized into tissues
Radial symmetry
Feed by stinging prey with nematocysts, mouth  gastrovascular cavity
Aquatic, soft bodied, carnivorous, radial symmetrical animals with stinging tentacles arranged in circles around their mouths
Simplest animals to have body symmetry and cells organized into tissues

20. Phylum Arthropoda Arthropods- “Jointed foot”
Ex. Insects, crustaceans, spiders
Segmented body, exoskeleton of chitin, jointed appendages
Segmented body – head and thorax or head/thorax/abdomen
Exoskeleton that is shed as they grow (molting)
A million species have been identified – more than 3x the number of all other animal species combined!

21. Nematoda - Roundworms Ex. pinworms Bilateral symmetry Tissue layers
Pseudocoelomate
Digestive system with mouth and anus
Molt (shed skin) as they grow
Simplest organisms to have one-way gut (mouth and anus)
Because they molt – they are considered to be more closely related to arthropods than other worms

22. Platyhelminthes - Flatworms
Ex. planarians, flukes, tapeworms
Bilateral symmetry
Three tissue layers
Acoelomate
Soft, unsegmented, flattened worms that have tissues and internal organ systems
Simplest animals to have three germ layers, bilateral symmetry, and heads

23. Annelida – Segmented worms
Ex. earthworms, leeches, bristleworms
Bilateral symmetry
Tissue layers
Coelomate

24. Annelida Systems 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

25. Phylum Mollusca Mollusks
Ex. Gastropods (snails), Bivalves (clams), Cephalopods (squid)
Internal or external shell
Bilateral symmetry
Tissue layers
Coelomate
Soft-bodied animals with internal or external shells
Complex organ systems

26. Phylum Echinodermata Echinoderms- “Spiny skin”
Ex. Sea Stars, Sea Urchins, Sand Dollars
Internal skeleton
Water vascular system (tube feet)
Radial symmetry
Skin is stretched over an internal skeleton of calcium carbonate plates
Water-vascular system – network of water-filled tubes that include suction-cuplike structures called tube feet (used for walking and gripping prey)
Most adult echinoderms exhibit five part radial symmetry
Deuterostomes – makes them more closely related to chordates than to other invertebrates (even though they have radial symmetry)

27. Chapter 26.2
Objectives
Describe characteristics of chordate phyla.

28. Cladogram of Chordates
Evolutionary relationships of chordates
Circles represent evolution of some important chordate adaptations

29. Nonvertebrate Chordates
Two invertebrate
Urochordata: tunicates
subphyla:
Cephalochordata: lancelets
Adult tunicates look like sponges and are filter feeders
no body symmetry
most display chordate features and bilateral symmetry only during larval stages
Lancelets are fishlike animals with bilateral symmetry that live in salt water.

30. Jawless Fishes No true jaws or teeth Lack vertebrae
Skeleton made of cartilage
Ex. Lampreys, hagfish
Do have part of skull (why they are considered vertebrates)
Have notochord as an adult
Lampreys – top picture
filter feeders as larvae; parasites as adults
adults typically attach themselves to fish, scrap away skin with rasping tongue, and then such host’s tissues and body fluids
called the “vampires of the sea”
Hagfish
pinkish grey wormlike body
secrete lots of slime
can tie their bodies into knots
no image forming eyes – just light detecting sensors on their bodies
feed on dead or dying animals using rasping tongue

31. Cartilaginous Fish Skeleton made of cartilage Paired fins
Most have tooth-like scales
Ex. Sharks, rays, skates
Paired fins allowed for greater control of body movement
Tail fins and powerful muscles gave greater thrust
Toothlike scales cover their bodies

32. Bony Fish Skeleton of true bone Paired fins, scales, gills
Swim bladder
Ex. Perch, bass, flounder

33. Amphibians Means “double life” Undergo metamorphosis
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

34. Amphibian Systems Digestive/Excretory: Nervous: Circulatory:
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)

35. Reptiles Vertebrates with lungs Scaly skin
Leathery shelled amniotic eggs
Ex. Lizards, snakes, turtles, crocodiles, dinosaurs
Developed adaptations that allow them to live out of the water (do not rely on water for part of life cycle)
well-developed lungs
scaly skin to protect it from water loss
amniotic eggs with leathery shell that allow them lay them on land (rather than in water)

36. Birds 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 reptiles (endothermic) – able to regulate own body temperature (only birds and mammals can do this – all other animals are cold-blooded (ectothermic)
Descended from Archaeopteryx (dinosaur with feathers)
Have strong but light-weight hollow bones to allow them to fly
Also have air sacs in addition to lungs to allow for constant air-flow (great need for oxygen when flying)

37. Mammals 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.

38. Groups of Mammals Monotremes Marsupials Placental mammals:
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