Transcript chapter24_Sections 4-8.ppt

Cecie Starr
Christine Evers
Lisa Starr
www.cengage.com/biology/starr
Chapter 24
Animals II: The Chordates
(Sections 24.4 - 24.8)
Albia Dugger • Miami Dade College
24.4 Amphibians: The First Tetrapods
• Amphibians, the first tetrapods, branched off from the lobefinned fishes
• Most spend some time on land, but return to the water to
reproduce
• amphibian
• Tetrapod with a three-chambered heart and scaleless skin
that typically develops in water, then lives on land as a
carnivore with lungs
The Move Onto Land
• Transition to land required many physical changes:
• Skeletal changes to develop front and hind limbs
• Division of the heart into three chambers to allow blood
flow in two circuits, one to the body and one to lungs
• Changes to the inner ear improved detection of airborne
sounds
• Eyes became protected from drying out by eyelids
Transition to Tetrapods
• Skeleton of a Devonian
lobe-finned fish, and
two early amphibians,
Acanthostega, and
Ichthyostega
Early Amphibians?
Modern Amphibians
• Salamanders and newts
resemble early
tetrapods in body form
Salamander Gait
• Early tetrapods
probably used the same
motion as salamanders
to walk in water before
one lineage ventured
onto land
ANIMATION: Salamander locomotion
To play movie you must be in Slide Show Mode
PC Users: Please wait for content to load, then click to play
Mac Users: CLICK HERE
Frogs and Toads
• Frogs and toads belong
to the most diverse
amphibian lineage
• Modern amphibians
such as the American
toad are carnivores
• The flattened disk
visible behind the eye is
the eardrum
Frogs
• Long, muscular
hind limbs allow
the adult frog to
leap
• The larval frog
(tadpole) is a
swimmer with a
long tail and no
legs
Declining Amphibian Diversity
• Amphibian populations throughout the world are declining or
disappearing – many due to shrinking or deteriorating habitats
• Other factors include introduction of new species in
amphibian habitats, long-term shifts in climate, increases in
ultraviolet radiation, and spread of pathogens and parasites
• Chemical pollution of aquatic habitats also harms amphibians
Frog Deformity
• Infection by a fluke
caused abnormal
limb development
Key Concepts
• The Transition From Water to Land
• Tetrapods, animals that walk on four legs, evolved from a
lineage of lobe-finned fishes
• Amphibians were the first tetrapod lineage
• They can live on land, but their eggs must develop in water
and their skin is not waterproof
24.5 Evolution of the Amniotes
• Amniotes, the first vertebrates able to complete their life cycle
on dry land, have water-conserving skin and kidneys, and
amniote eggs
• Fertilization usually takes place inside the female’s body
• amniote egg
• Egg with internal membranes that allow the amniote
embryo to develop away from water
Amniote Egg
• A bird’s egg has a hard
shell that encloses the
embryo and amniote
membranes (yolk sac,
amnion, chorion, and
allantois)
Amniote Egg
yolk sac
embryo
hardened shell
amnion
chorion
allantois
albumin (“egg white”)
Fig 24.14, p. 384
ANIMATION: Amniote egg
To play movie you must be in Slide Show Mode
PC Users: Please wait for content to load, then click to play
Mac Users: CLICK HERE
Two Lineages
• There are two lineages of amniotes: reptiles (including birds
and the extinct dinosaurs) and mammals
• reptile
• Amniote subgroup that includes lizards, snakes, turtles,
crocodilians, and birds
• dinosaur
• Reptile lineage abundant in the Jurassic to Cretaceous;
now extinct with the exception of birds
Proposed Amniote Lineages
• Mammals diverged early: Note the reptile clade includes birds
Proposed Amniote Lineages
Mammals
Turtles
Lizards, snakes
Crocodilians
Birds
Reptiles
Fig 24.15, p. 384
Dinosaurs of the Jurassic
• Shows the early bird Archaeopteryx and an early mammal
Key Concepts
• The Amniotes
• Amniotes have waterproof skin, and their eggs contain
membranes that enclose the embryo in fluid
• These and other traits allowed the amniotes to expand into
dry habitats
• Reptiles (including birds) and mammals are the two
modern amniote lineages
ANIMATION: Crocodile Body Plan
To play movie you must be in Slide Show Mode
PC Users: Please wait for content to load, then click to play
Mac Users: CLICK HERE
24.6 Nonbird Reptiles
• The major groups of nonbird reptiles are lizards, snakes,
turtles, and crocodilians
• All nonbird reptiles are ectotherms, which adjust their
temperature by their behavior
• By contrast, birds and mammals are endotherms, which
produce heat by metabolic activity
Key Terms
• ectotherm
• Animal that controls its internal temperature by altering its
behavior; for example a lizard
• endotherm
• Animal that generates heat by its metabolism; for example
a bird or mammal
Lizards and Snakes
• Lizards and snakes are
covered with scales
• All snakes are
carnivores with teeth,
but not all have fangs
• Most lay eggs, but
some give birth to live
young
• Hognose snakes
Turtles
• Turtles and tortoises
have a bony shell
attached to their
skeleton, and a horny
beak rather than teeth
• Some feed on plants
and others are
predators
• Galápagos tortoise
Crocodilians
• Spectacled caiman
• Crocodiles, alligators,
and caimans are the
closest living relatives of
birds
• All are carnivores and
spend much of their
time in water
ANIMATION: Tortoise Shell and Skeleton
To play movie you must be in Slide Show Mode
PC Users: Please wait for content to load, then click to play
Mac Users: CLICK HERE
24.7 Birds: Reptiles With Feathers
• Birds are descendants of feathered dinosaurs
• Body plans of most species are highly modified for flight, with
lightweight bones, powerful muscles
• Feathers increase wing-surface area and increase lift
• bird
• An animal with feathers
Adapted to Flight
• Birds have lightweight
bones and a large
sternum
Adapted to Flight
porous,
lightweight
bone
pelvic
girdle
pectoral girdle
sternum
(breastbone)
B
Fig 24.18b, p. 386
Energy for Flight
• Flight requires a lot of energy: Among modern vertebrates,
only birds and bats fly by flapping a pair of wings
Energy For Flight
• Energy for flight is provided by aerobic respiration and a
highly efficient respiratory system
• A unique system of air sacs keeps air flowing continually
through lungs
• A relatively large, four-chambered heart pumps blood quickly
from the lungs to wing muscles and back
Mating House Sparrows
• Lacking a penis, the male must bend his body so his cloaca
covers his mate’s
ANIMATION: Avian Bone and Muscle
Structure
To play movie you must be in Slide Show Mode
PC Users: Please wait for content to load, then click to play
Mac Users: CLICK HERE
24.8 Mammals: The Milk Makers
• Mammals diversified after dinosaurs were gone
• Like birds, mammals are endotherms; their fur (or hair) helps
them retain internally produced heat
• mammal
• Animal with hair or fur
• Females secrete milk from mammary glands
Mammalian Traits
• Only mammals have
four differently shaped
kinds of teeth
• Having teeth of multiple
shapes allows
mammals to process a
wide variety of foods
Mammalian Traits
molars
premolars
incisors
canines
Fig 24.20, p. 387
Three Mammalian Lineages
• monotremes
• Egg-laying mammals
• marsupials
• Mammals in which young are born at an early stage and
complete development in a pouch on the mother’s surface
• placental mammals
• Mammals in which a mother and her embryo exchange
materials by means of an organ called the placenta
Monotremes
• Oldest mammalian
lineage
• Lay eggs with a leathery
shell, similar to reptiles
• Three species: duckbilled platypus and two
kinds of spiny anteater
Marsupials
• Most marsupials live in
Australia and nearby
islands
• Kangaroos and koalas
are the best known
• The opossum is native
to North America
Placental Mammals
• Maternal and embryonic
tissues form a placenta
• Embryos grow fast, and
offspring are born fully
formed
• Placental mammals
outcompete other
mammalian lineages
ANIMATION: Structure of the placenta
To play movie you must be in Slide Show Mode
PC Users: Please wait for content to load, then click to play
Mac Users: CLICK HERE
ANIMATION: Mammalian Dentition
To play movie you must be in Slide Show Mode
PC Users: Please wait for content to load, then click to play
Mac Users: CLICK HERE