1. VERTEBRATES
Ch. 25 & 26

2. Life
Birds
Mammals

3. What are vertebrates? Animals with a backbone
Examples: fishes, frogs, turtles, snakes, birds, alligators, mammals, etc.
Vetebra comes from the Latin word vertere, meaning “to turn”

4. Phylum Chordata Chordates are named for an embryonic structure
The notochord is a flexible rod that extends through much of the length of the body
Most chordates are vertebrates, but
There are two groups of invertebrates that are chordates (tunicates & lancelets)

5. Vertebrates are Chordates
Vertebrates are animals with a skull and a backbone
An endoskeleton
In vertebrates, only remnants of the notochord remain
Example: the cartilage discs in your backbone
Most vertebrates have paired limbs

7. Other important features
Hinged Jaws
Importance?

9. Vertebrates Hagfish and lampreys
Do not have hinged jaws or paired limbs

10. Vertebrates
Fishes
Have hinged jaws
aquatic

11. Tetrapods: Amphibians, reptiles, birds, mammals
Tetrapods (“four footed”) have 2 sets of paired limbs
This allowed them to??
Snakes are tetrapods!
They evolved to become legless

12. Activities 1) Finish grasshopper dissection & turn in.
2) pHSuccessnet.com
Ch. 25 webquest
Activity 25.1

14. The 1st jawed vertebrates.
FISHES
The 1st jawed vertebrates.
2 Categories:
Cartilaginous fishes – Chondrichthyes
Skeletons are flexible and made entirely of cartilage
Sharks and rays
Bony fishes
Skeletons contain bone hardened by calcium deposits

15. Bony Fishes Stiff skeleton made of calcium
Gills to extract O2 from water
Operculum- flap that covers the gills
- pumps water over the gills
Lateral line system

16. Bony Fishes Stiff scales made of bone
The outer mucus allows fish to glide more easily through the water
Most are carnivores
Some feed upon plankton or algae (seaweed)

17. Bony Fishes Air Sac Heart ---> 2 Chambers
“swim bladder” makes fish more buoyant
Also aids in hearing by transmitting vibrations
Heart ---> 2 Chambers
The ventricle (1) pumps blood to the gills
The atrium (2) receives blood returning from the body

18. 2 Chamber Heart One way circuit Very basic Much slower than
land vertebrates

19. Video
Life Science: Fish and Amphibians

20. Review
1) What is the major difference between cartilaginous and bony fishes?
2) Describe the function of the lateral line system.
3) List the general characteristics of bony fishes.
4) List and contrast the 3 classes of bony fishes.

21. Perch Dissection

22. Perch Dissection

23. The First Tetrapods
Amphibians are descendants of four limbed ancestors that were fully aquatic 400 mya
Limbs and legs evolved in fishes– moved to land (50 million years)
Leg-like limbs allowed for movement through dense marine vegetation

24. The First Tetrapods
Acanthostega have gill structures, but amphibian-like limbs

25. Amphibians Amphibios= “living a double life” in Greek
Many live in their larval stage in water and adult stage on land
Eggs do not have shells so are easily dried out
Water is often necessary for laying eggs
Adults generally:
Have Lungs
Have moist skin without
scales

26. Stage of Development Tadpoles --> the larvae of amphibians
Legless aquatic plant-eaters with:
Gills, lateral line system, long tail
Metamorphosis into adult form leads to:
Lungs in place of gills
Eardrums
No lateral line system
4 legs
***Some amphibians do not have a terrestrial stage, some amphibians do not have an aquatic stage

27. Other characteristics
Moist skin often assists lungs with gas exchange
May also contain poison glands
Amphibians have a 3-chambered heart
Remember fish have 2 chambered heart

28. Allows for 2 pathways of blood flow
One to the lungs and skin for gas exchange
One to the other tissues
Advantage??
The Atria collect blood returning to heart
Ventricle pumps blood out

29. Amphibian Diversity about 8% of vertebrates Frogs Salamanders
insect eaters
Toads are terrestrial frogs
Salamanders
Caecilians
Legless & blind; burrow in soil

30. Video
Life Science: Fish and Amphibians

31. General Characteristics of Amphibians?1) 2) 3) 4) 5)
What if they were forced to live on land and have no access to water?

32. AMNIOTES Amniotes- reptiles, birds, mammals General Characteristics:
Live on land (do not need water)
Amniotic egg
Internal fertilization
Water-tight skin

33. Amniotic Egg Waterproof egg with a shell
Amnion- protects embryo from drying out

34. Water-tight Skin Enriched with keratin Reptiles- scales
Prevents dehydration
Reptiles- scales
Birds- feathers
Mammals- nails, hair, horns

35. Reptiles

36. Reptile Characteristics
Water-tight, scaly skin that molts
Lungs
Lay eggs
Cold-blooded
(ectotherms)

37. Komodo Dragon Hunting a Water Buffalo

38. BIRDS Ancestor- dinosaur Endothermic amniotes Adaptations for flight:
Wing shape
Feathers (also for insulation)
Several weight-reducing features

39. Review of Frog Dissection
Where is the tympanic membrane?
How can you tell a male from a female?
What is the cloaca?
What is the purpose of the fat bodies?
What are 3 differences between reptiles and amphibians?

40. Wing Shape
Airfoil-shaped wings

41. Air-sac System Function with lungs for respiration
Helps supply high level of O2 that supports a high metabolism.
Also reduces density of bird

42. Weight-Reducing Features
Air-sacs
Honey-combed bones
Absence of some internal organs

43. Circulatory System Efficient oxygen delivery 4-chambered heart
Adaptation for active, endothermic lifestyle

44. MAMMALS
Mesozoic era- evolved from mammal-like reptiles, therapsids

45. Mammal Characteristics
Endothermic
Mammary glands- milk
Hair- insulation
Lungs with diaphragm
4-chambered heart
Internal fertilization

46. Mammal Diversity
Monotremes- lay eggs, cloaca

47. Mammal Diversity
Marsupials- “pouched mammals”

48. Mammal Diversity
Placental Mammals- Embryo completes development within the uterus; placenta forms & feeds embryo