Fishes, Amphibians, and Reptiles
Table of Contents
What Is a Vertebrate?
Fishes
Amphibians
Reptiles
Vertebrate History in Rocks
Fishes, Amphibians, and Reptiles - What Is a Vertebrate?
Ancient Jawless Fish
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.
Fishes, Amphibians, and Reptiles
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.
Fishes, Amphibians, and Reptiles
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.
Fishes, Amphibians, and Reptiles
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
Fishes, Amphibians, and Reptiles
Fishes, Amphibians, and Reptiles
Fishes, Amphibians, and Reptiles
Quick Review:
What are the four major functions of animals?
1.
2.
3.
4.
Obtaining food & oxygen
Keeping conditions stable
Movement
Reproduction
Fishes, Amphibians, and Reptiles
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
Fishes, Amphibians, and Reptiles - What Is a Vertebrate?
Building Vocabulary
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:
chordate
ectotherm
notochord
endotherm
vertebra
Examples:
An members
All
ectothermofisthis
an phylum
animal whose
are called
body
chordates.
does not
produce much internal heat.
The phylum name Chordata comes from the
notochord,
a an
flexible
rod that
supports
a chordate’s
The
beaver is
example
of an
endotherm—an
back. whose body regulates its own temperature by
animal
controlling the internal heat it produces.
You can see in Figure 2 that the backbone is formed
by many similar bones called vertebrae.
Fishes, Amphibians, and Reptiles
End of Section:
What Is a
Vertebrate?
Fishes, Amphibians, and Reptiles
FISH
Fishes, Amphibians, and Reptiles
Question:
What is the name for a person
who studies fishes?
Answer: Ichthyologist
Fishes, Amphibians, and Reptiles
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, Amphibians, and Reptiles
•Fishes have a closed
circulatory and 2 chambered
heart
•Blood moves from the heart
to gills and then to the rest of
the body
Fishes, Amphibians, and Reptiles
Three Major Groups of Fish
•Jawless Fish (no hinged jaw)
•Cartilaginous Fish (more flexible than bone)
•Bony Fish (majority of all fish species)
Fishes, Amphibians, and Reptiles
Class Agnatha (Jawless Fish)
•Cartilagenous
•Simplest and oldest
known vertebrates
•No Jaw
•No scales
•Scavengers or
parasites
•Lamprey & Hagfish
Fishes, Amphibians, and Reptiles
Class Chondrichthyes (Cartilaginous Fishes)
•Hinged jaw
•Paired fins
•Scales
•Cartilaginous skeleton
•Muscles attached to skin, not skeleton
•Skates, Rays, and Sharks
Fishes, Amphibians, and Reptiles
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 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.
Fishes, Amphibians, and Reptiles - Fishes
Previewing Visuals
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.
Fishes, Amphibians, and Reptiles
End of Section:
Fishes
Fishes, Amphibians, and Reptiles
What is an Amphibian?
•Vertebrates
•Ectotherms
•Both aquatic and terrestrial animals!
•Two major groups:
1. Salamanders
2. 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 Land
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.
Fishes, Amphibians, and Reptiles - Amphibians
Sequencing
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.
Fishes, Amphibians, and Reptiles
End of Section:
Amphibians
Fishes, Amphibians, and Reptiles
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.
Fishes, Amphibians, and Reptiles - Reptiles
Adaptations for Life on Land
The membranes and shell of an amniotic egg protect the
developing embryo.
Fishes, Amphibians, and Reptiles - Reptiles
Characteristics of a Lizard
This lizard, a Jackson’s
chameleon, has many
adaptations that help
it survive in its
environment.
Fishes, Amphibians, and Reptiles - 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.)
Fishes, Amphibians, and Reptiles - Reptiles
The Sex Ratio of Newly Hatched Alligators
Reading Graphs:
At which temperature(s) did
only females hatch?
29.4ºC
Fishes, Amphibians, and Reptiles - 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.
Fishes, Amphibians, and Reptiles - 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.
Fishes, Amphibians, and Reptiles - Reptiles
Extinct Reptiles–The Dinosaurs
Dinosaurs were the earliest vertebrates
that had legs positioned directly beneath
their bodies.
Fishes, Amphibians, and Reptiles
Fishes, Amphibians, and Reptiles - 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
Reptiles have a
thick, scaly skin
that prevents water
loss.
Detail
Reptile eggs have
a shell and
membranes that
keep them from
drying out.
Detail
A reptile’s kidneys
concentrate wastes
before excreting
them so that little
water is lost.
Fishes, Amphibians, and Reptiles
Interpretation of Fossils
The pattern of vertebrate evolution is branching.
Fishes, Amphibians, and Reptiles
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.
Fishes, Amphibians, and Reptiles
End of Section:
Graphic Organizer