1. Table of Contents What Is a Vertebrate? Fishes Amphibians Reptiles
Vertebrate History in Rocks

2. Ancient Jawless Fish - What Is a Vertebrate?
Look backward in time, into an ocean 530 million years ago. There you see a strange-looking creature—a jawless fish—that is about as long as your index finger.

3. Chordate Characteristics
Chordates belong to the phylum Chordata
Members of this phylum include vertebrates and invertebrates
3 common characteristics: a notochord, nerve cord, and gill slits
A notochord is a flexible rod that runs down the back
A nerve cord serves as the connection between the brain and the nerves on which messages travel back and forth
All chordates have pharyngeal slits that either disappear before birth or function as gills for their entire lives.

4. Human Embryo

5. Characteristics of Chordates
- What Is a Vertebrate?
Characteristics of Chordates
This lancelet shows the characteristics of a chordate: a notochord, a nerve cord down its back, and gill slits.

6. Characteristics of Vertebrates
Vertebrates have backbones that are part of an internal skeleton (endoskeleton)
Vertebra include any of the bones or segments composing the spinal column, consisting typically of a cylindrical body that allows the spinal cord to pass through it
Vertebrae include all the bones that make up the backbone
Internal skeleton or endoskeleton protects the internal organs of the body, helps give the body shape, and gives muscles a place to attach
*Having an endoskeleton allows vertebrates to grow bigger than animals with exoskeletons

9. What are the four major functions of animals?
Quick Review:
What are the four major functions of animals?
Obtaining food & oxygen
Keeping conditions stable
Movement
Reproduction

10. Keeping Conditions Stable
Major groups of vertebrates control their body temperatures in one of 2 ways:
An ectotherm is an animal that does not produce much internal heat so their body temperature changes depending on the temperature of its environment (fish, amphibians, and reptiles)
An endotherm is an animal that regulates its own temperature by controlling the internal heat it produces (birds and mammals)
Endotherms body temperatures do not change much and this allows them to live in many different environments

11. Building Vocabulary - What Is a Vertebrate?
A definition states the meaning of a word or phrase by telling about its most important feature or function. After you read the section, reread the paragraphs that contain definitions of Key Terms. Use the information you have learned to write a definition of each Key Term in your own words.
Key Terms:
Key Terms:
Examples:
ectotherm
endotherm
Examples:
chordate
An ectotherm is an animal whose body does not produce much internal heat.
All members of this phylum are called chordates.
notochord
The phylum name Chordata comes from the notochord, a flexible rod that supports a chordate’s back.
The beaver is an example of an endotherm—an animal whose body regulates its own temperature by controlling the internal heat it produces.
vertebra
You can see in Figure 2 that the backbone is formed by many similar bones called vertebrae.

12. End of Section: What Is a Vertebrate?

13. FISH

14. What is the name for a person who studies fishes?
Question:
What is the name for a person who studies fishes?
Answer: Ichthyologist

15. Characteristics of Fishes
Fins are thin membranes stretched across a bony support that provides larger surface area for fishes to push against the water
Most fishes have external fertilization where female eggs are released outside the female’s body
In contrast, sharks and some other species have internal fertilization
Nervous/sense organs help fish to find food and avoid predators

16. Characteristics of Fishes
Most fishes obtain oxygen through gills.
What are gills?
A gill is a respiratory organ found in many aquatic organisms that extracts dissolved oxygen from water

17. Fishes have a closed circulatory and 2 chambered heart
Blood moves from the heart to gills and then to the rest of the body

18. Three Major Groups of Fish
Jawless Fish (no hinged jaw)
Cartilaginous Fish (more flexible than bone)
Bony Fish (majority of all fish species)

19. Class Agnatha (Jawless Fish)
Cartilagenous
Simplest and oldest known vertebrates
No Jaw
No scales
Scavengers or parasites
Lamprey & Hagfish

20. Class Chondrichthyes (Cartilaginous Fishes)
Hinged jaw
Paired fins
Scales
Cartilaginous skeleton
Muscles attached to skin, not skeleton
Skates, Rays, and Sharks

21. Class Osteichthyes (Bony Fishes)
Largest group of fishes
Skeleton made of bone and cartilage
Hinged jaws
Paired fins
Hard, protective scales
Covered gills (operculum)

22. - Fishes
Bony Fishes
A bony fish has jaws, scales, a pocket on each side of the head that holds the gills, and a skeleton made of hard bones.

23. Previewing Visuals - Fishes
Before you read, preview Figure 12. Then write two questions that you have about the diagram in a graphic organizer like the one below. As you read, answer your questions.
Structure of a Fish
Q. What is a swim bladder?
A. A swim bladder is an internal, gas-filled sac that helps stabilize the fish at different depths in the water.
Q. What is the function of the tail fin?
A. It helps provide the power for swimming.

24. End of Section: Fishes

25. Aquatic and terrestrial animals! Two major groups: Salimanders
What is an Amphibian?
Vertebrates
Ectotherms
Aquatic and terrestrial animals!
Two major groups:
Salimanders
Frogs and Toads

26. What Is an Amphibian? - Amphibians
During its metamorphosis from tadpole to adult, a frog’s body changes dramatically.

27. Living on Land - Amphibians
Many adult amphibians have lungs, a heart with three chambers, and a double-loop circulatory system.
The two upper chambers of the heart are called atria (atria is plural for atrium).
The ventricle is the lower chamber of the heart where oxygen-rich blood mixes with oxygen-poor blood.

28. Respiration and Circulation Activity
- Amphibians
Respiration and Circulation Activity
Click the Active Art button to open a browser window and access Active Art about respiration and circulation.

29. Sequencing - Amphibians
Make a cycle diagram like the one below that shows the different stages of a frog’s metamorphosis during its life cycle. Write each step of the process in a separate circle.
Frog Metamorphosis
Adult frog
Tail is absorbed.
Fertilized egg
Front legs develop.
Tadpole hatches.
Hind legs develop.

30. More on The Frog Life Cycle
- Amphibians
More on The Frog Life Cycle
Click the PHSchool.com button for an activity about the frog life cycle.

31. End of Section: Amphibians

32. What is a Reptile?
A reptile is an ectothermic vertebrate with lungs and scaly skin
Reptiles include turtles, snakes, lizards, alligators & crocodiles
Ancestors of modern reptiles were first vertebrates to live completely outside of an aquatic environment
Land animals must be able to conserve water and the skin, kidneys, and eggs of reptiles have these adaptations
Kidneys are organs that filter wastes from the blood and excreted through urine.
Reptiles have internal fertilization and lay their eggs on land
An egg with a shell and internal membranes that keep the embryo moist is called an amniotic egg.

33. Adaptations for Life on Land
- Reptiles
Adaptations for Life on Land
The membranes and shell of an amniotic egg protect the developing embryo.

34. Characteristics of a Lizard
- Reptiles
Characteristics of a Lizard
This lizard, a Jackson’s chameleon, has many adaptations that help
it survive in its
environment.

35. The Sex Ratio of Newly Hatched Alligators
- Reptiles
The Sex Ratio of Newly Hatched Alligators
The temperature of the developing eggs of the American alligator affects the sex ratio of the young. (Sex ratio is the number of females compared with the number of males.)

36. The Sex Ratio of Newly Hatched Alligators
- Reptiles
The Sex Ratio of Newly Hatched Alligators
Reading Graphs:
At which temperature(s) did only females hatch?
29.4ºC

37. The Sex Ratio of Newly Hatched Alligators
- Reptiles
The Sex Ratio of Newly Hatched Alligators
Drawing Conclusions:
What effect does the temperature of developing eggs have on the sex of the baby alligators?
The warmer the incubation temperature, the greater the proportion of males.

38. The Sex Ratio of Newly Hatched Alligators
- Reptiles
The Sex Ratio of Newly Hatched Alligators
Calculating:
If 100 eggs developed at 31.7ºC, about how many of the young would be male?
According to the graph, out of the 50 alligators that were incubated at 31.7ºC, about 40 (or 80%) were males. So 80% of 100 eggs (80) could be expected to hatch as males.

39. Extinct Reptiles–The Dinosaurs
Dinosaurs were the earliest vertebrates that had legs positioned directly beneath their bodies.

41. Identifying Main Ideas
- Reptiles
Identifying Main Ideas
As you read the information under the heading “Adaptations for Life on Land,” write the main idea in a graphic organizer like the one below. Then write three supporting details that further explain the main idea.
Main Idea
Reptiles are adapted to conserve water.
Detail
Detail
Detail
Reptiles have a thick, scaly skin that prevents water loss.
Reptile eggs have a shell and membranes that keep them from drying out.
A reptile’s kidneys concentrate wastes before excreting them so that little water is lost.

42. Click the PHSchool.com button for an activity about reptiles.
More on Reptiles
Click the PHSchool.com button for an activity about reptiles.

43. End of Section: Reptiles

44. Interpretation of Fossils
- Vertebrate History in Rocks
Interpretation of Fossils
Fossils are the preserved remains of remains or traces of animals, plants, and other organisms from the remote past.
Fossils most often form in layers of sedimentary rock which is made of hardened clay, sand, mud, or silt.

45. A paleontologist is a scientist who studies paleontology, learning about the forms of life that existed in former geologic periods, chiefly by studying fossils. Types of fossil preservation: Cold or Warm/Dry environments favor the fossilization process because lack of decomposing bacteria Famous Fossil Discoveries
Lucy
Ardi
Megalosaurus

46. Interpretation of Fossils
- Vertebrate History in Rocks
Interpretation of Fossils
The pattern of vertebrate evolution is branching.

47. Oldest Living Things On Our Planet

48. Asking Questions - Vertebrate History in Rocks
Before you read, preview the red headings. In a graphic organizer like the one below, ask a what or how question for each heading. As you read, write answers to your questions.
Questions
Answers
How do fossils form?
Fossils form from imprints or the remains of organisms.
How are fossils interpreted?
Scientists examine fossil structure and make comparisons to present-day organisms.

49. Click the SciLinks button for links on fossils.
- Vertebrate History in Rocks
Links on Fossils
Click the SciLinks button for links on fossils.

50. Click the Video button to watch a movie about interpreting fossils.
- Vertebrate History in Rocks
Interpreting Fossils
Click the Video button to watch a movie about interpreting fossils.

51. End of Section: Vertebrate History in Rocks

52. Graphic Organizer Main Idea
The larvae of amphibians are adapted for life in water, and adult amphibians are adapted for life on land.
Detail
Detail
Detail
Larvae have tails for swimming; adults have legs for walking.
Larvae have gills; adults have lungs.
Larvae have one-loop circulatory systems and two-chambered hearts; adults have two-loop circulatory systems and three-chambered hearts.

53. End of Section: Graphic Organizer