
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.

http://en.wikipedia.org/wiki/Human_pharynx


Human Embryo

Fishes, Amphibians, and Reptiles - 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.


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


Quick Review:

What are the four major functions of animals?

1. Obtaining food & oxygen2. Keeping conditions stable3. Movement4. Reproduction


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


Building VocabularyA 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: Examples:

- What Is a Vertebrate?

chordate 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.

vertebra You can see in Figure 2 that the backbone is formed by many similar bones called vertebrae.

Key Terms: Examples:ectotherm

endotherm

An ectotherm is an animal whose body does not produce much internal heat.

The beaver is an example of an endotherm—an animal whose body regulates its own temperature by controlling the internal heat it produces.


End of Section:What Is a

Vertebrate?


FISH


Question:

What is the name for a person who studies fishes?

Answer: Ichthyologist


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

Fishes, Amphibians, and Reptiles - Fishes

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


• Fishes have a closed circulatory and 2 chambered heart

• Blood moves from the heart to gills and then to the rest of the body


Three Major Groups of Fish

• Jawless Fish (no hinged jaw)

• Cartilaginous Fish (more flexible than bone)

• Bony Fish (majority of all fish species)


Class Agnatha (Jawless Fish)

• Cartilagenous• Simplest and oldest

known vertebrates• No Jaw• No scales• Scavengers or

parasites• Lamprey & Hagfish


Class Chondrichthyes (Cartilaginous Fishes)

• Hinged jaw

• Paired fins

• Scales

• Cartilaginous skeleton

• Muscles attached to skin, not skeleton

• Skates, Rays, and Sharks


Class Osteichthyes (Bony Fishes)

• Largest group of fishes

• Skeleton made of bone and cartilage

• Hinged jaws

• Paired fins

• Hard, protective scales

• Covered gills (operculum)

Fishes, Amphibians, and Reptiles - Fishes

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

http://en.wikipedia.org/wiki/Diversity_of_fish

http://library.thinkquest.org/05aug/00548/DissectionGame.html


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.

Previewing Visuals

Structure of a FishQ. 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.

- Fishes


End of Section:Fishes


What is an Amphibian?• Vertebrates

• Ectotherms

• Aquatic and terrestrial animals!

• Two major groups: 1. Salimanders2. Frogs and Toads

Fishes, Amphibians, and Reptiles - Amphibians

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

Fishes, Amphibians, and Reptiles - Amphibians

Living on LandMany 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.


Respiration and Circulation Activity

Click the Active Art button to open a browser window and access Active Art about respiration and circulation.

- Amphibians


SequencingMake 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

Fertilized egg

Tadpole hatches.

Hind legs develop.

Front legs develop.

Tail is absorbed.

- Amphibians


More on The Frog Life Cycle

Click the PHSchool.com button for an activity aboutthe frog life cycle.

- Amphibians

http://phschool.com/webcodes10/index.cfm?fuseaction=home.gotoWebCode&wcprefix=ced&wcsuffix=2033


End of Section:Amphibians


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.

http://www.sandiegozoo.org/animalbytes/t-snake.html

http://www.sandiegozoo.org/animalbytes/t-lizard.html

http://www.sandiegozoo.org/animalbytes/t-crocodile.html

Fishes, Amphibians, and Reptiles - Reptiles

Adaptations for Life on LandThe membranes and shell of an amniotic egg protect the developing embryo.


Characteristics of a LizardThis lizard, a Jackson’s chameleon, has many adaptations that help it survive in itsenvironment.


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.)

- Reptiles



29.4ºC

Reading Graphs:

At which temperature(s) did only females hatch?

- Reptiles



The warmer the incubation temperature, the greater the proportion of males.

Drawing Conclusions:

What effect does the temperature of developing eggs have on the sex of the baby alligators?

- Reptiles



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.

Calculating:

If 100 eggs developed at 31.7ºC, about how many of the young would be male?

- Reptiles


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

http://science.nationalgeographic.com/science/prehistoric-world/dinosaur-extinction/


Main Idea

Detail Detail Detail

Identifying Main IdeasAs 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.

Reptiles are adapted to conserve water.

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.

- Reptiles


More on Reptiles

Click the PHSchool.com button for an activity about reptiles.

- Reptiles

http://phschool.com/webcodes10/index.cfm?fuseaction=home.gotoWebCode&wcprefix=ced&wcsuffix=2034


End of Section:Reptiles

Fishes, Amphibians, and Reptiles - Vertebrate History in Rocks

Interpretation of FossilsFossils are the preserved remains of remains or traces of animals, plants, and other organisms from the remote past.

http://www.classzone.com/books/earth_science/terc/content/investigations/es2903/es2903page01.cfm

Fossils most often form in layers of sedimentary rock which is made of hardened clay, sand, mud, or silt.




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

http://www.enchantedlearning.com/subjects/dinosaurs/dinofossils/Fossiltypes.html

http://en.wikipedia.org/wiki/Lucy_(Australopithecus)

http://news.nationalgeographic.com/news/2009/10/091001-oldest-human-skeleton-ardi-missing-link-chimps-ardipithecus-ramidus.html

http://www.enchantedlearning.com/subjects/dinosaurs/dinos/Megalosaurus.shtml

Fishes, Amphibians, and Reptiles - Vertebrate History in Rocks

Interpretation of FossilsThe pattern of vertebrate evolution is branching.


Oldest Living Things On Our Planet


Asking QuestionsBefore 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.

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.

Questions Answers

- Vertebrate History in Rocks


Links on Fossils

Click the SciLinks button for links on fossils.


http://www.scilinks.org/fromoutside.asp?sciLINKSNumber=scn-0235&type=student


Interpreting Fossils

Click the Video button to watch a movie aboutinterpreting fossils.



End of Section:Vertebrate

History in Rocks


Graphic Organizer

The larvae of amphibians are adapted for life in water, and adult amphibians are adapted for life on land.

Larvae have tails for swimming; adults have

legs for walking.

Detail Detail Detail

Main Idea

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.


End of Section:Graphic Organizer

table of contents

Documents

reptiles fishes

internal heat

body shape

cylindrical body

body temperature changes

exoskeletons fishes

internal organs

nerve cord