Phylum Chordata
Ch.17, 18, 19, 20, 21, 22
Introduction to
Phylum Chordata:
Chapter 17
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~45,000 species
Bilaterally symmetrical, deuterostome
animals
Notochord (Greek: noton=back,
chorda=cord)
Complete digestive tract
Pharyngeal slits
Postanal tail
Aquatic and terrestrial animals
Ventral, contractile blood vessel (heart)
General Characteristics of
Phylum Chordata
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Subphylum Vertebrata
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Class
Class
Class
Class
Class
Class
Class
Cephalapidomorphi (Lampreys)
Chondrichthyes (Rays, Sharks, Skates)
Osteichthyes (Bony Fish)
Amphibia (Frogs, Toads, Salamanders)
Reptilia (Snakes, Lizards, Alligators)
Aves (Birds)
Mammalia (Mammals)
Where we are going…..
The Fish
Chapter 18
Lampreys
Fishlike; jawed; paired appendages and
cartilaginous skeleton; sucking mouth
with teeth and rasping tongue
 Seven pairs of pharyngeal slits
 Inhabitants of marine and freshwater
environments in temperate regions
 Generally prey on other fish:
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◦ Mouth of adult is suckerlike and surrounded by
lips that have sensory and attachment
functions
◦ Numerous teeth line the mouth and cover a
movable tonguelike structure
◦ The lamprey attaches to its prey with its lips
and teeth and uses its tongue to rasp away
scales
◦ Lampreys have salivary glands with
anticoagulant (like leech) secretions and feed
mainly on the blood of their prey!
Class Cephalaspidomorphi
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Sharks, Rays, and Skates
Fishlike, jawed, paired
appendages and
cartilaginous skeleton
Tail fin with large upper lobe
Lack opercula (gill cover),
swim bladder (helps in
buoyancy-use liver instead),
and lungs
Carnivores or scavengers
Mostly Marine
~820 species
Class Chondrichthyes
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Tough skin with placoid scales
(see pg. 282). Scales project
posteriorly and give the skin a
touch texture.
Dried shark skin has been used
for sandpaper!
Shark teeth are actually
modified placoid scales!
The row of teeth on the outer
edge of the jaw is backed up by
rows of teeth…as the outer teeth
wear and become useless, newer
teeth move into position from
the next row.
In young sharks, this
replacement is rapid, happening
every 7 or 8 days!
Class Chondrichthyes
Sharks range in size from less than 1
meter to greater than 10 meters!
 The largest living shark is the whale
shark that is not even a predator but a
filter feeder!
 The fiercest and most feared sharks are
the great white sharks.
 Extinct species may have reached lengths
of 15 meters or more.
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Class Chondrichthyes
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Skates and Rays
◦ Specialized for life on the ocean floor,
generally inhabiting shallow waters,
where they use their teeth to feed on
invertebrates
◦ Modified to live on ocean floor by the
lateral expansion of the pectoral fins
into winglike appendages
◦ Often use colors on dorsal side as
camouflage
◦ The sting ray has a tail modified into a
defensive lash (the barb)
◦ Also, in this group are the electric rays
and manta rays.
Class Chondrichthyes
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Bony Fish
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Larges vertebrate class ~24,000 species
Have lungs or swim bladder
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Have operculum
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Locomotion: fins and body wall, muscles run in a
zig zag pattern and each contraction can be
powerful
Most modern fish are predators and spend much
time searching for food (prey varies greatly)
Have a central nervous system with a brain and
spinal cord
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◦ Have at least some bone in their skeleton/scales
◦ Gas-filled sacs along the dorsal wall of the body cavity
that regulates buoyancy
◦ Gill cover
Class Osteichthyes
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Circulation:
◦ Closed circulatory system in which a heart
pumps blood with red blood cells through a
series of arteries, capillaries, and veins
◦ In most fish, blood passes through the heart
once with every circuit around the body
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Gas Exchange:
◦ To maintain oxygen levels underwater, fish
must pass large quantities of water across gill
surfaces and extract the small amounts of
oxygen present in the water (fish use different
methods of doing this)
Bony Fish
Circulation & Gas Exchange
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Electroreception:
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Electric fish:
◦ The detection of electrical fields that a fish or other
organisms in the environments generate.
◦ All organisms produce weak electrical fields from
the activities of nerves and muscles
◦ Example: Spiny dogfish sharks locate prey using
electroreception. This shark can find and eat a
flounder that is buried in sand, but cannot find a
dead flounder
◦ Some fish are not only capable of electroreception,
but can also generate electrical currents!
◦ Best known-Electric Eel
◦ Electric Eel is found in rivers in South America
◦ The organs for producing electrical current are in
the trunk of the electric eel and can deliver shocks
in excess of 500 volts!
Electroreception & Electric Fish
Class Amphibia
Chapter 19
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Skin with mucoid secretions
Possess lungs/gills
Moist skin serves as
respiratory organ
Lack scales, feathers, and
hair
Larvae usually aquatic and
undergo metamorphosis to
become adult
Two atrial chambers in the
heart
Occur on all continents
except Antarctica, but they
are absent from many
oceanic islands
We will focus on two
Orders: Caudata & Anura
Class Amphibia
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Salamanders and Newts
Possess a tail throughout life
Both pairs of legs, when present, are unspecialized
~115 of the 350 species live in North America!
Most terrestrial salamanders live in moist forest-floor litter
and have aquatic larvae.
Newts live most of their life in water and usually retain their
caudal fin.
Salamanders range in length from only a few centimeters to
1.5 meters.
The largest North American salamander is the hellbender,
which reaches lengths of about 65cm.
Most salamanders have internal fertilization, but not
copulation.
Larvae are similar to adults, but smaller. The aquatic larval
stage usually metamorphoses into a terrestrial adult
Order Caudata
Frogs and Toads
~3,500 species
Most live in moist environments, but some even
occur in very dry deserts
 Adults lack tails
 Hindlimbs are long and muscular and end in
webbed feet
 Fertilization is almost always external, and eggs
and larvae are typically aquatic, larval stages,
called tadpoles, have well-developed tails
 “Frog” and “Toad” really aren’t that different
scientifically. Toad usually means anurans with
dry and warty skin that are more terrestrial than
other members in the order-which is true in
many families! True toads belong to the family
Bufonidae.
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Order Anura
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Amphibian skin lacks a covering of scales,
feathers, or hair, but it is highly glandular
and its secretions aid in protection.
These glands keep the skin moist to prevent
drying
They also produce toxic chemicals that
discourage potential predators.
Chromatophores are specialized cells of the
skin that are responsible for skin color and
color changes-cryptic coloration and mimicry
are common in amphibians
Class Amphibia External Structure
Most adults are carnivores that
feed on a variety of invertebrates,
although some anurans are more
diverse.
 Example: bullfrogs will prey on
small mammals, birds, and other
amphibians!
 The main factors that determine
what amphibians will eat are prey
size and availability.
 Most amphibians locate their prey
by site and simply wait for prey to
pass by.
 Also, amphibians have the first
true tongue and use it as a feeding
mechanism!
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Class Amphibia Digestion
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Most people have experienced that amphibians
have moist skin, and amphibian skin also has
many capillary beds.
These 2 factors permit the skin to function as a
respiratory organ.
Gas exchange across skin is called Cutaneous
Respiration and can occur in water or on land.
Exchanges of oxygen and carbon dioxide require
most surfaces and exposure or respiratory
surfaces to air may result in rapid water loss!
Most amphibians have lungs, but larvae may use
gills in the beginning that will seal up and
become lungs later in life.
Amphibian Gas Exchange
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Amphibians are ectothermic, meaning that
they depend on external heat sources to
maintain body temperature.
Many amphibians are nocturnal and remain
in cooler burrows or under moist leaf litter
during hot times.
Amphibians may warm themselves by
basking in the sun or on warm surfaces.
Basking after a meal is common because
increased body temp increases the rate of
metabolism.
Amphibian
Temperature Regulation
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Sound production is primarily a reproductive
function of male anurans (frogs/toads).
◦ Advertisement calls attract females to breeding
areas and announce to other males that a given
territory is occupied.
◦ Advertisement calls are species specific.
◦ Females respond by making reciprocation calls to
indicate receptiveness.
◦ The use of sound to attract mates is useful in
organisms that occupy widely dispersed habitats
and must come together for breeding.
◦ Also, because many frogs often come to the same
pond for breeding, finding a mate of the proper
species could be chaotic, but vocalizations help in
this manner!
Amphibian Vocalization
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Frogs and Toads also use vocalization as
distress calls.
◦ Distress calls are not associated with
reproduction and both a male or a female can
produce these calls
◦ Distress calls are in response to pain or being
seized by a predator and may be loud enough to
cause a predator to release the frog or toad.
◦ The distress call of the South American jungle
frog is a loud scream similar to the call of a cat in
distress!
Amphibian Vocalization
Record the Vital Statistics in your Notes.
How big does this salamander get?
Is there an aquatic larval stage?
Are there Red Hills Salamanders in the
Shoals?
5. What are the primary threats to these
salamanders?
6. Who owns 60% of the salamanders’
habitat that is destroying it by clear
cutting trees?
1.
2.
3.
4.
Wildlife Alert: Red Hills Salamander
pg. 309
Answer the Questions Above
Class Reptilia
Chapter 20
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Dry skin with epidermal scales
Respiration via Lungs
Internal Fertilization
First Vertebrates to have Amniotic Eggs
◦ Have extraembryonic membranes that protect the
embryo, cushion the embryo, supplies food to
embryo, promote gas transfer, and store waste
materials.
◦ These eggs are made for land development
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Terrestrial embryonic development
We will focus on three Orders:
◦ Testudines (Turtles)
◦ Squamata (Snakes, Lizards, Worm Lizards)
◦ Crocodilia (Crocodiles, Alligators)
Class Reptilia Characteristics
~225 species
Teeth absent in adults and replaced by a beak
Short broad body
Bony Shell Present-in some turtles, shell has hinges
(box turtle) which allows openings to close when turtle
withdraws into shell!
 Have long life spans, most live 14 or more years, and
large tortoises, like those of the Galapagos Islands,
may live in excess of 100 years! (Tortoises are
completely terrestrial)
 All turtles are oviparous: females make nests for eggs
in soil, then lay the eggs, then cover the eggs with
soil. Development takes from four weeks to one year,
and the parent does not attend to the eggs during this
time. The young are independent when they hatch!
 Slow growth rates and long juvenile periods make
turtles vulnerable to extinction in the face of high
mortality rates, but luckily, in recent years, turtle
conservation programs have been enacted.
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Order Testudines (Turtles)
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Order Squamata is divided
into three suborders:
◦ Suborder Sauria-The Lizards
◦ Suborder Serpentes-The Snakes
◦ Suborder Amphisbaenia-Worm Lizards
Order Squamata
~3,300 species
Usually have 2 pairs of legs
Vary in length from only a few centimeters to as large
as 3 meters!
 Many lizards live on surface areas but retreat under
rocks or logs when necessary, others are burrowers or
tree dwellers
 Example Species:
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◦ Geckos
 Commonly found in subtropical areas, nocturnal, capable of
clicking vocalizations, large eyes with unique pupils are adapted
for night vision, adhesive disks on their digits allows them to cling
to trees and walls.
◦ Chameleons
 Use a long, sticky tongue to capture insects, well known for their
ability to change color in response to illumination, temperature, or
their behavioral state
◦ Gila Monster & Komodo Dragon
 The only venomous lizards, heavy-bodied lizards are native to
southwestern North America. Lizard bites are seldom fatal to
humans!
Lizards
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~2,300 species
The vast majority of snakes are not dangerous to humans,
but about 300 species are venomous
Worldwide:30,000-40,000 people die from snake
bites/year. United States: fewer than 100/year.
Snakes are elongated and lack limbs
The skeleton may contain more than 200 vertebrae and
pairs of ribs!
Snakes possess skull adaptations that facilitate swallowing
large prey
Elongation in snakes has resulted in the reduction or loss of
the left lung and displacement of the gall bladder, the right
kidney, and often, the gonads.
Most snakes are oviparous, although a few, such as the
New World Boas and garter snakes, give birth to live
young!
Snakes
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Only 21 species!
Living crocodiles include the alligators, crocodiles, gavials,
and caimans.
Crocodiles have not changed much over their 170 million
year history
Snout is elongated and often used to capture food by a side
ways sweep of the head.
Nostrils are at the tip of the snout, so the animal can breath
while mostly submerged.
The muscular and long tail is used for swimming, offensive
and defensive maneuvers, and attacking prey.
Teeth are used only for seizing prey.
Food is swallowed whole, but if a prey is too large, the croc
will tear it apart by holding onto a limb and rotating their
bodies wildly until the prey is dismembered.
Crocodilians are oviparous and display parental care of
hatchlings that is similar to birds.
Order Crocodilia
Alligator or Crocodile??
1.
2.
3.
4.
5.
6.
7.
Copy the Vital Statistics
How big do adult Kemp’s Ridley Sea Turtles
get?
Where are adults primarily found nesting?
What do they feed on?
When does nesting occur?
When was Kemp’s Ridley Sea Turtle placed
on the federal endangered species list?
What is the recovery plan’s goal number of
females nesting in a season?
Wildlife Alert:
Kemp’s Ridley Sea Turtle
Page 324 Answer the Questions
Above in your Notes
Class Aves (Birds)
Chapter 21
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Adaptations for flight
A high metabolic rate
Endothermic (heat is derived from own body
system)
Lack teeth
Similarities between birds and reptiles are so
striking, the bird is often referred to as
“glorified reptiles”
~9,000 species of living birds divided into
about 27 orders
Orders are divided according to behaviors,
songs, anatomical features, and ecological
niches
Bird Characteristics
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Covering of feathers on a bird is called plumage.
Feathers have 2 primary functions essential for
flight: form the flight surfaces that provide lift
and steering and they prevent excessive heat
loss.
Feathers also have roles in courtship, incubation,
and waterproofing.
Birds preen feathers to keep them smooth,
clean, and in place.
Mature feathers receive constant wear, so birds
periodically shed and replace feathers in a
process called molting.
Birds have 3 types of feathers:
◦ Contour-cover body, wings and tail
◦ Down-insulating feathers
◦ Filoplum-(pinfeathers)have sensory functions
Feathers
Bones of most birds are lightweight,
yet strong
 Some bones have large air spaces
and internal reinforcement of bones
for strength
 Birds have a reduced number of skull
bones and a bill that replaces teeth.
 The demand for lightweight bones is
countered in some birds with other
requirements
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◦ Example: Some aquatic birds have dense
bones (heavier), which help reduce
buoyancy during diving.
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Furcula (wishbone):
◦ Paired clavicles that fuse together to
serve as an additional site for the
attachment of flight muscles.
Skeleton
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Wings of birds are adapted for different kinds of
flight, but no matter if a bird glides, soars, or has
rapid flapping flight, the mechanics of staying
aloft are similar:
◦ Bird wings form an airfoil
◦ Anterior margin of wing is thicker than posterior margin
◦ Upper surface of the wing is slightly convex (outward),
and the lower is slightly concave (inward)
◦ Air passing over the wing travels farther and faster than
air passing under the wing, decreasing air pressure on
the upper surface of the wing and creating LIFT!
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The tail of a bird serves a variety of balancing,
steering, and braking functions during flight.
Flight
Most birds have huge appetites to support
their high metabolic rate that makes
endothermy and flight possible
 Bird Bills and Tongues are modified for a
variety of feeding habits and food
sources.
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Nutrition and Digestion
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All birds are oviparous (lay eggs that develop outside of the body of
the female)
Many birds establish a territory prior to mating to allow that species
to mate without interference.
Mating may follow the attraction of a mate to a territory:
◦ Male woodpeckers drum on trees to attract females
◦ Male ruffed grouse fan their wings on logs and create sounds that can be heard
for miles!
◦ Cranes have a courtship dance that includes stepping, bowing, stretching, and
jumping displays.
Most birds are monogamous meaning a single male pairs with a single
female during the breeding season, and some birds such as swans,
geese, and eagles, pair for life!! These types of pairs generally share
duties of caring for the nest, eggs, and young.
 Some birds are polygynous meaning the males mate with more than
one female and the female care for the eggs and chicks.
 A few bird species are polyandrous meaning the females mate with
more than one male. The males guard the eggs in this case.
 Nest construction usually begins after pair formation, but some birds
do not make nests. (Example: Emperor penguins, the nest is the
webbed foot of the father!)
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Reproduction & Development
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Group of eggs laid and chicks produced by a female is
called a clutch.
Most birds incubate their eggs & birds turn the eggs to
prevent the membranes from adhering to the egg and
deforming the embryo!
Adults of some species sprinkle eggs with water to cool
and humidify them!
One or two days before hatching, the young bird
penetrates an air sac at eh blunt end of its egg, inflates
its lungs, and begins breathing, then the young bird
breaks free from the egg using an “egg tooth” on the tip
of the upper jaw to free itself!
Altricial: totally dependent on parents and are often
naked at hatching
Perocial: are alert and lively at hatching, usually
covered in down feathers and can already walk, run,
swim, and feed themselves (although one parent is
usually present to lead the young to food and shelter)
Reproduction & Development
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Migration: periodic round trips between
breeding and nonbreeding areas.
Most migrations are annual and allows birds
to avoid climatic extremes and to secure
adequate food, shelter, and space throughout
the year.
Birds use two forms of navigation:
◦ Route-based navigation
 Involves keeping track of landmarks (visual or
auditory) on an outward journey so that those
landmarks can be used on the return trip
◦ Location-based navigation
 Based on establishing the direction of the destination
from information available at the journey’s site of
origin and involves the use of sun compasses, other
celestial cues, and/or the earth’s magnetic field
Migration
Mammals
Chapter 22
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Skin is thick and protective and has an insulating
covering of hair
Adaptations of teeth which are specialized and the
digestive tract allows for a variety of food resources
Efficient circulatory and gas exchange systems
support endothermy (having a body temp determined
by heat derived from the animal’s own metabolism)
Brain has an expanded cerebral cortex that processes
information from various sensory structures.
Specialized kidneys allow for excretion of wastes
without excessive water loss.
Complex behavioral patterns enhance mammalian
survival.
Most mammals are viviparous and have reproductive
cycles that help ensure internal fertilization and
successful development
Have mammary glands-produce milk for young
General Mammal Characteristics
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Order Primates: Lemurs, Monkeys, Apes,
Humans
Order Rodentia: Squirrels, rats, beavers,
porcupines
Order Cetacea: Whales, dolphins, porpoises
Order Carnivora: Dogs, cats, raccoons, sea
lions, otters
Order Proboscidea: African & Indian
elephants
Order Perissodactyla: Horses, rhinoceroses,
zebras
Order Artiodactyla: Pigs, camels, deer, sheep,
giraffes, cattle
Some Orders in Class Mammalia
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Skin:
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◦ Consists of epidermal
and dermal layers
◦ Protects from injury,
invasion of
microorganisms, and
sun’s uv light
◦ Important in
temperature
regulation, sensory
perception, excretion,
and water regulation
Hair:
◦ Uniquely mammalian
◦ A coat of hair, called
pelage, usually
consists of two kinds
of hair-long guard
hairs & shorter,
insulating underhairs.
◦ Because hair is
composed largely of
dead cells, it must be
periodically molted
External Structure
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Hearts: four chambered that keep blood in the
systematic and pulmonary circuits separate.
One important adaptation for mammals
concerns the circulatory system distributing
gases and nutrients to a fetus across the
placenta
High metabolic rates require efficient gas
exchange…most mammals have separate
nasal and oral cavities and longer snouts,
which provide for increased surface area for
warming and moistening inspired air.
Mammalian lungs inflate using a negative
pressure mechanism and mammals also
possess a diaphragm that separates the
thoracic and abdominal cavities.
Inspiration (breathing in) results from
contraction of the diaphragm and expansion of
the rib cage, both of which allow air to enter
the lungs.
Circulation & Gas Exchange
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Mammals have complex behaviors
that enhance survival:
◦ Visual cues
 Ex: Bristled fur, arched back, and open
mouth of cat communicate a clear message
to predators
◦ Pheromones
 Ex: Young of mammals recognize parents
and parents recognize young by smell. Also,
some mammals urinate to mark territories,
and of course, skunks use chemicals to
ward off predators
◦ Auditory
 Ex: Herd animals stay together and remain
calm as long as familiar sounds (hooves
walking over dry grasses and twigs,
stomachs rumbling) are uninterrupted.
◦ Vocalizations
 Ex: Humans talking in social interactions
Behavior