Transcript Vertebrates: Part I

Vertebrates: Part I
Fishes, Reptiles,
& Amphibians
Vertebrates
Animals that have backbones are called
vertebrates
 All vertebrates belong to the phylum
Chordata

– Animals in this phylum are called
chordates
• Fish, amphibians, reptiles, birds, and mammals
Chordate Traits
Presence of gill slits at some stage of
development
 Have a flexible skeletal rod called a
notochord

– In vertebrates, the notochord is present
only in the embryo stage
• It gets replaced by a backbone that surrounds
and protects the spinal cord
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Endoskeleton
Vertebrate Evolution
The first vertebrates appeared on the
earth about 500 million years ago
 They were water-dwelling, fish-like
animals
 Over time they evolved into many
different kinds of fishes
 Gradually some fish developed
adaptations that permitted them to
move from the water onto the land

Section 30-1
Mammals
Birds
Amphibians
Fishes
Nonvertebrate
chordates
Invertebrate ancestor
Reptiles
Fish Characteristics

Live in freshwater or saltwater
 Ectotherms: animals with bodies that receive
heat from the outside
– Body temperature depends on the temperature of
the environment
– Often described as cold-blooded
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Gills for respiration
Have streamlined bodies and use fins for
locomotion
Very good sense of smell
Highly developed nervous systems
Mostly external fertilization
Classes of Fishes
 Agnatha
(Jawless Fish)
–Lampreys
 Chondrichthyes
(Cartilaginous
Fish)
–Sharks, rays
 Osteichthyes
(Bony Fish)
–Most common fish
Jawless Fish
Lampreys and hagfish
 Do not have jaws
 Only vertebrate without a vertebral
column as an adult
 Parasites and scavengers

– Lampreys attach to a host, rip
into their host’s flesh, then feed upon the
blood and body fluids of the host
Cartilaginous Fish
Cartilage is a firm yet flexible
connective tissue that occurs at most
joints of your skeleton and makes up
the skeleton in cartilaginous fishes.
 Includes sharks, rays, and skates
 Unlike the jawless fish, cartilaginous fish
have jaws that evolved from the first
pair of skeletal rods that supported the
gills of jawless fish

Cartilaginous Fish continued

Most cartilaginous sharks are carnivores
– Sharp senses and sharp teeth make them well
adapted for life as predators

Some of the largest sharks are filter feeders
– Whale shark strains water to remove plankton
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More dense than ocean water so they must
keep swimming to float above the sea floor
– For some, swimming is also what makes a current
of water pass over the gills so the fish can get
oxygen
Bony Fishes
Greatest number of fish species are
bony fishes
 Have skeletons made of bone
 Have other adaptations that help them
live in many kinds of water habitats

– Buoyancy control
– Scales
– Gills and lungs
Buoyancy Control

Have an organ called a swim bladder
– Similar to a balloon
– Helps them adjust their depth in the water
by adding or subtracting air
– Allows the fish to maintain a buoyancy
• Buoyancy is the force of fluid pushing an object
up
Gills and Lungs

Most bony fish depend only
upon gills for their gas exchange
– They do not rely on movement to get
oxygen from the water
– They can pump water through the mouth
and into the gill chamber by a movement
by the gill cover
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Some have both gills and lungs such as
the African lungfish
– Go to the surface to gulp air when they
need more oxygen
Scales and Fins
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The outside of a bony fish is covered with a layer
of smooth scales that overlap each other
Scales are also covered with a thin layer of
mucus
These are adaptations that help the fish move
through water with little resistance
Bony fishes have paired and unpaired fins
– The paired pectoral and pelvic fins are used to
steer, brake, back up, and move up and down
– The caudal fin
propels the fish
Fish Structure
Homework due tomorrow
List 3 characteristics of fish that make
them adapted to life in water.
 Why does a cartilaginous fish have to
swim constantly? What adaptations
make it unnecessary for a bony fish to
swim all the time?
 What is an ectotherm?
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Reptile Characteristics

Dry, waterproof body covering made of
scales
– Helps to conserve water while living on land
– Prevents gas exchange through the skin
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Spongy lung with an increased internal
surface area for gas exchange
 3-chambered heart with a partial wall dividing
the chambers to prevent mixing of stale and
fresh blood
 Jacobson’s organ: sense organ on the roof
of reptile’s mouth for smelling
Reptile Temperatures
Ectotherms, but most can regulate their
internal temperature well anyway
 Adaptations that reptiles have to keep
their body temperatures about as warm
as yours for much of the day

– They bask in the sun when the air is too
cool
– Seek shade when it is too hot
Reptile Reproduction
Reproduce entirely on land
 Eggs fertilized internally
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– Eggshell is tough and leathery that keeps
the embryo from drying out
– Special membranes transfer food from the
egg yolk, remove wastes, and take in
oxygen
Lizards and Snakes
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They may look different, but lizards and
snakes are closely related
 Carnivores
 Snakes still have hipbones and remnants of
hind legs even though they don’t have
appendages
 Snakes have limited hearing and poor
eyesight
– Great sense of smell and taste
– Use their tongues to find prey and gather
information about the environment
Turtles and Tortoises
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All have shells
– When in danger, they pull their heads, legs, and
tails into their shells
– Formed from bony plates connected to their ribs
and vertebrae
– Shell covered by a layer of tough material
• Makes the markings and color patterns on the shell
Turtles and Tortoises
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Turtles
– Shells are flat and streamlined
– Live in ponds, lakes, rivers, or the ocean
• Lay eggs on land
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Tortoises
– Dome-shaped shells
– Live on land
Alligators and Crocodiles

Closest living relative to dinosaurs
 Have large, deep scales
 Unlike most reptiles, alligators and crocodiles
care for their young
– Females guard their eggs
– Both males and females protect their babies
Alligators and Crocodiles
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Alligators
– Broad head with a rounded snout
– Live mostly in North America and Asia
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Crocodiles
– Narrow head with a triangle shaped snout
– Live in tropical areas of America, Africa, Asia, and
Australia
Homework due TOMORROW
Identify the characteristics of reptiles
that make them suited to life on land.
 Explain the similarities and differences
among the three groups of reptiles.
 The largest reptiles all live in areas
where it is warm year-round. Based on
what you know about reptiles, why is
this so?
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Amphibians
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The word amphibian means “double life”
– Most spend part of their live in water and part on
land
• Mud puppies spend their whole live in water
• Tree frogs live entirely on land
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Respiratory gases are exchanged through the
skin as well as in their lungs
 They are ectotherms and are cool to the
touch
 Require moist environment even though they
can live on land
Amphibian Reproduction
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Must reproduce in water
– Female lays eggs in a pond, swamp, or stream
– Fertilized externally by the male
– If water is scarce, some amphibians have
adaptations to make up for it
• Desert toads produce a moist foam to lay their eggs in
Amphibian Metamorphosis
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Many amphibians go through a
metamorphosis where they have a tadpole
stage
– In amphibian species where the adult remains a
water-dweller, the changes from tadpole to adult
are minor
– Frogs and toads change completely as it becomes
an adult
Frog Life Cycle
Groups of Amphibians
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Salamanders and newts
– Amphibians with tails
– Smooth, moist skin
– Habitats
• Some live in relatively dry habitats
• Some in very moist
• Some even live in water their entire lives
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Frogs and toads
– Amphibians without tails
– Most frogs live their lives in and around water
Eat or Be Eaten
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Frogs and toads eat insects, worms, small
crustaceans, and small mollusks
– Eaten by herons, large fish, and snakes
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Most amphibians can defend themselves only
by jumping or swimming away
 Toads have bumps on their bodies which
secrete a bad tasting material so most
animals leave toads alone
Dormant Amphibians
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In cold climates…
– Frogs and salamanders burrow into the
mud at the bottom of lakes or rivers that do
not freeze completely
– Toads and land salamanders burrow deep
into the ground over the cold winter
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Body activities slow down tremendously
– Heart barely beats
– Blood barely flows
– Lungs stop working entirely
Frogs

Well developed hind legs for jumping and swimming
– strong, powerful
 5 toes with webbing for swimming
 Eyes bulging above head
– Can pull against roof of mouth to help hold food in mouth
– Can float just under the water with only their eyes showing
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Tympanic Membrane just behind their eyes – no
external ears
Mouth
–
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–
–
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Insect trap
Extends from ear to ear
Sticky tongue
No teeth on lower jaw
Vomerine teeth to hold prey
Problems with life on land
Drying
out
Respiration
Reproduction
Movement
Temperature Control
Homework due tomorrow
Describe how amphibians hibernate.
 List 3 characteristics of amphibians.
For each, explain whether it is an
adaptation to land or to water.
 How is an adult frog like a tadpole?
How is an adult frog different from a
tadpole?
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AMPHIBIANS
means
Breathes
with
Reproduce in
________
reproduction
____________
fertilization
metamorphosis
___________& ___________
___________& ___________
Ectotherms
Have tails
No tails
______ toes
_____ teeth to
hold prey
________ bulge
& can drop into
mouth to hold
prey
Sticky _________
attached to front of
bottom jaw
Torpor
Secrete bad
tasting mucus as
defense
FISH
Breathes
with
____________
fertilization
Examples
No jaws
No vertebral
column as an adult
Most fish
Whole skeleton
made of cartilage
Skeletons made
of _________
Examples
Have to keep
swimming
For water to move
over _______ for
respiration
_______________
for depth control
Pump water into
gills with _____
________
Paired and unpaired
______
REPTILES
___ chambered heart
with division to prevent
blood mixing
Ectotherms
____________ on
roof of mouth for
smelling
__________ & __________
reproduction
Limited hearing
& eyesight
_________
fertilization
Reproduce on
_________
Great sense of
______ & ______
Use ______ to
gather information
__________ & __________
Closest relatives
to dinosaurs
Unlike other
reptiles, care for
their _________
__________ & __________
Water-dwellers
Shells formed by
bony plates attached
to _____ & _____
Shells ________
& streamlined
Live on land
________-shaped
shell
Tuck into ____
when in danger