The Animal Kingdom
Chapters 3 and 4: Vertebrates
Phylum Chordata
• All chordates have the following three
characteristics at some time in their lives:
1. Notochord: soft, flexible rod of cartilage.
It develops into the vertebrae in most
chordates.
2. Nerve cord: develops into the brain and
spinal cord.
3. Gill slits: paired openings in the throat.
Develop into gills in some chordates.
This lancelet shows the characteristics of a
chordate: a notochord, a nerve cord down its
back, and gill slits.
Notochord
Gill Slits
Nerve cord
Vertebrates
• Most chordates are also
known as vertebrates.
–The notochord is
replaced by bone or
cartilage.
–They have a
complete
endoskeleton made
of bone or cartilage.
Ectothermic Vertebrates
• Some vertebrates are ectothermic
(cold-blooded)—this means their
body does not produce internal
heat. Their body temperature
changes with the temperature of the
environment. Fish, amphibians and
reptiles are ectotherms.
Endothermic Vertebrates
• Other vertebrates are endothermic
(warm-blooded)—this means they
regulate their own temperature by
producing internal heat. Birds and
mammals are endotherms.
7 Classes of Vertebrates
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Class Agnatha—jawless fish
Class Chondrichthyes—cartilage fish
Class Osteichthyes—bony fish
Class Amphibia—amphibians
Class Reptilia—reptiles
Class Aves—birds
Class Mammalia—mammals
Fish
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All live in water and breath through gills.
All have a 2-chambered heart.
All are ectothermic.
Most have fins and scales.
30,000 different species classified into
three classes: Agnatha,
Chondrichthyes, and Osteichthyes.
Class Agnatha: Jawless fish
• Simplest of all fish.
• No jaws, scales or paired fins.
• Cartilage skeletons with sucker-shaped
mouths.
• Some are external parasites; others are
scavengers.
• Include two species: Lamprey and
Hagfish
Lamprey
External parasites
that live in fresh
water.
Use their sucker-shaped
mouths to attach to the
bodies of other fish.
Hagfish
A very successful scavenger of cold-water
oceans. It is totally blind and produces a
lubricating slime through glands in its skin.
Class Chondrichthyes:
Cartilage Fish
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All have cartilage skeletons—no bones.
All have jaws, scales and paired fins.
Uncovered (naked) gills.
Placoid (toothlike) scales—embedded in
skin.
• Most live in salt water.
• Examples: Sharks, skates
and rays.
Sharks, Skates and Rays
Skates lay eggs in egg cases while
rays bear live young.
Tiger Shark
Notice the rows of
replacable teeth and the
movable upper jaw.
Sting Ray with poisonous spine.
Class Osteichthyes:
Bony Fish
• All have skeletons made of bone.
• All have jaws, scales and paired fins.
• Gills covered by a bony flap called an
operculum.
• Swim bladder helps it to swim without
sinking.
• Some live in fresh water, others in salt
water.
• 95% of all fish belong to this class.
- Fishes
Bony Fishes
Class Amphibia:
Frogs, Toads, Salamanders and
Newts
• Amphibios—means double life.
• All amphibians breathe through gills as larva
and through simple, sac-like lungs as adults.
Some respiration also occurs through the skin.
• All have a three-chambered heart.
• All have moist, smooth skin with no scales.
• All are ectothermic
• Many hibernate during winter and estivate
during hot, dry summers.
Amphibian Metamorphosis
Eggs
Larva (tadpole)
Adult:
mature
young
The length of time spent as a larva depends on the
species, the water temperature, and the availability
of food. However, for most species, the entire process
is accomplished in 12 to 14 weeks.
Frogs and Toads
Both have short, broad bodies with no neck or tail.
Their back legs are larger than their front legs.
Southern Leopard Frog
•Family: Ranidae
•Skin: smooth and slimy
•Back legs: adapted for jumping
•Lay eggs in clusters
American Toad
•Family: Bufonidae
•Skin: warty and dry
•Back legs: short for walking
•Lay eggs in long chains
•Poison glands behind eyes
Salamanders and Newts
•Long, slender bodies with short legs and a long tail.
•Newts are actually small salamanders.
Biological Indicators
• Biological Indicator—species whose overall health
reflects the health of their particular ecosystem.
• Amphibians are good biological indicators.
– They are sensitive to chemical and
environmental changes.
– Their decline is often the first sign that an area is
being polluted.
– Amphibian populations are on the decline,
worldwide. Scientists believe the depletion of
ozone is the main reason.
Frog Mutations
Class Reptilia:
Turtles, Alligators, Lizards, Snakes
• Reptiles are well suited for life on land:
– Dry, scaly waterproof skin conserves
water. Many molt their skin as they
grow.
– Breathe through lungs their entire life.
– Internal fertilization
– Lay amniotic eggs (egg with a built-in
food source and a protective shell). This
keeps the embryo from drying out. The
shell is leathery.
- Reptiles
Adaptations for Life on Land
•The
membranes
and shell of
an amniotic
egg protect
the
developing
embryo.
Turtles and Tortoises
All are covered by a hard shell on both top and bottom.
Painted Turtle
•Prefer watery environments
•Ominvores
•Flat shells
Galapagos Tortoise
•Prefer dry land environments
•Herbivores
•High, domed shells
Green Sea Turtle
•Leave the ocean only to lay eggs
•Herbivores or Omnivores
•Can stay underwater for 3 weeks
•Legs are paddle-like
Alligators
Crocodiles
Large reptiles found mostly in tropical
climates.
Only upper teeth show when
mouth is closed.
Broad head with rounded snout
Both upper and lower teeth show
when mouth is closed.
Narrow head with pointed snout
Lizards and Snakes
•Both lizards and snakes belong to the same and largest order
of reptiles.
•About 3,000 species of lizards and 2,700 species of snakes
exist.
•They are distinguished from each other by the fact that
snakes lack arms, legs, ears and eyelids. (There are a few
species of legless lizards).
Extinct Reptiles
• Dinosaurs ruled for 160 million
years during the Mesozoic Era.
• They went extinct 65 million years
ago.
• They are different from other reptiles
because they walked like birds and
mammals with their legs straight
under them rather than out to the
sides.
• Many scientists believe they are
more closely related to birds than to
modern reptiles.
Class Aves
Birds
• Endothermic vertebrates with a normal
body temperature of 104-108 degrees.
• Have many unique characteristics related
to their ability to fly.
1. Feathers (3 types)
Contour Feathers —cover the wings
and body to streamline the bird for
flight
Down Feathers —soft, fluffy and
close to the body to keep the bird
warm
Flight Feathers —located on the
wings and tail to create “lift” when
flying
Feather Structure
Feathers are held together and in place by a hollow tube
called the shaft. The shaft is made of a very hard material
called keratin.
2. Skeletal System
• Thin, hollow
bones make a
bird’s skeleton
light weight.
• Many are fused
together for
extra support.
3. Digestive System
• Extremely efficient
and fast. Some birds
digest a meal in less
than one hour. This
provides the energy
needed for flight.
• Must eat often.
• Crop stores food.
• Gizzard, grinds food
(birds have no teeth).
4. Excretory System
• Birds do not store liquid wastes (too
heavy)
• Instead they filter highly concentrated uric
acid from the blood and eliminate it along
with the solid wastes through one opening
called the cloaca.
5. Respiratory System
• Must be able to get
oxygen from air at
high altitudes.
• Using air sacs
attached to their
lungs, birds can get
oxygen both when
they inhale and
when they exhale.
• Air sacs also make
the bird lighter.
Above is a simplified diagram of the bird
respiratory system. The actual lung itself is
the small, thin part between the two larger
air sacs. As air passes through, oxygen is
removed. In real life, air is continually
passed through the lungs, but this diagram
only shows one breath as it travels through
the bird.
6. Circulatory System
• All birds have a
four chambered
heart to keep the
oxygen-rich blood
separate from the
oxygen-poor blood.
• Heart beats rapidly
(more than 1000
beats per minute)
for rapid circulation.
7. Reproductive System
• Birds use internal fertilization and
produce amniotic, hard-shelled eggs.
• Two methods for rearing young:
– Large clutch (many eggs)—young
are well developed and active when
born: ducks and quails.
–Small clutch (few eggs)—young are blind
and helpless when born: robin and eagle
Class Mammalia
• Endothermic animals with hair or
blubber to keep warm.
• Reproduce sexually and produce milk
through mammary glands to feed their
young.
• Four-chambered heart.
• Breathing is aided by the diaphragm.
Three Sub-classes (based on
how their young develop)
1. Monotremes—egg-laying mammals.
Examples: duck-billed platypus and
the echidna.
Platypus
Echidna
2. Marsupials—
pouched mammals.
Young are born
premature and
continue their
development in the
mother’s pouch.
Examples:
kangaroo,
opossum, koala
and wombat.
Koala
Red Kangaroo
3. Placental Mammals—young develop
inside the mother’s uterus and are
nourished by a placenta. Examples: all
other mammals.
Orders of Mammals
Order Monotremata—platypus and
echidna: egg laying mammals
Order Marsupialia—pouched mammals:
young born premature and continue
development in their mother’s pouch
Orders of Mammals
Order Insectivora—moles and
shrews: eat insects, burrow in ground.
Order Rodentia—rodents: chisel-like
teeth for gnawing. Largest order
Order Chiroptera—bats: flying mammals
Order Lagomorpha—rabbits: long ears,
two pair of front teeth, long hind legs
Orders of Mammals
Order Carnivora—meat eaters: large
canine teeth and sharp claws
Order Primates—chimps,
monkeys, apes humans: opposable
thumbs, rotating forearms, flexible
shoulders,binocular vision
Order Dermoptera—flying lemurs:
skin wings that allows them to glide,
unrelated to other lemurs (primates)
Orders of Mammals
Order Artiodactyla—deer, antelope,
moose, elk, etc: even-toed hoofed mammals
Order Proboscidea—Asian and African
elephants: trunked mammals
Order Perrisodactyla—horses,
rhinos, and tapirs: odd-toed
hoofed mammals
Order Hyracoidea—hyraxes: rodentlooking mammals with hoofs and large
incisors used only for defense
Orders of Mammals
Order Tubulidentata—aardvarks:
toothless, hoofed mammals
Order Edentata—anteaters, armadillos
and sloths:toothless (nearly toothless
mammals) Anteaters are the only
completely toothless members of this group
Order Pholidota—pangolins (spiny anteaters)
bodies are covered by scaly plates
Orders of Mammals
Order Cetacea—dolphins, whales and
porpoises: marine mammals that do
not leave the water. Breath through
blow-hole
Order Pinnipedia—seals, seal lions,
and walruses: marine mammals
that leave the water regularly.
Eat fish.
Order Sirenia—manatees and dugongs:
marine mammals that stay in water. Eat
aquatic plants and breath through nostrils