Transcript Animal Form and Function

Phylum: Chordata
Chapter 34
What you need to know!
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The 4 chordate characteristics.
Adaptations that allowed animals to
move onto land.
Traits which distinguish each of the
following groups: Chondrichthyes,
Osteichthyes, Amphibia, Reptilia, Birds,
and Mammalia.
How the 3 classes of mammals differ in
their reproduction.
Characteristics of all Chordates
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Notochord: Longitudinal,
flexible rod located between
the digestive and the nerve
cord
Nerve cord (dorsal, hollow):
eventually develops into the
brain and spinal cord
(arthropods ventral)
Pharyngeal slits: become
modified for gas exchange,
jaw support, and/or hearing
Muscular, postanal tail
Neurulation (Vertebrates)
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Neural Tube: dorsal folding of the
ectoderm forming a hollow nerve tube
Neural Crest: embryonic cells
(mesoderm) near the neural tube that
migrate throughout the body to form
special bones like the jaw and cranium
Animation:
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http://learningobjects.wesleyan.edu/neurul
ation/animation.php
Macroevolutionary Trends
Vertebrata
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Pronounced Cephalization: concentration of
sensory and neural equipment in the head
Cranium (skull): encloses brain
Endoskeleton: notochord becomes cartilage or
bone (vertebral column) enclosing the hollow
nerve chord
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Bone is more advanced than cartilage
Hinged Jaw
Closed circulatory system with a ventral
chambered heart
Land Adaptations
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Gills  lungs
Paired lobed fins  legs (tetrapod)
Amniotic Egg (shelled egg): several
extraembryonic membranes that are not part
of the embryo, but produced by embryonic
tissue:
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Amnion: protects embryo, contains amniotic fluid
for shock absorption
Allantois: forms extra sac for waste disposal and
gas exchange
Yolk Sac: nutrient stockpile
Chorion: gas exchange
Amniotic Egg
Major Divisions
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Fish
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Class Chondrichthyes: flexible endoskeletons and
jaws (i.e. shark and stingray)
Class Osteichthyes (bony fish): most numerous
vertebrates, boney endoskeleton, scales (i.e. trout
and salmon)
Class Amphibia: gas exchange across skin
(most use lungs), soft water-based eggs, larvae
have two-chambered hearts, adults have three
chambers (i.e. frogs and salamanders)
Class Reptiles: gas exchange in lungs,
intercourse, amniotic egg, scales (keratin),
ectothermic, three chambered heart (i.e.
turtles, lizards, and alligators)
Major Divisions
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Birds (subdivision of reptiles): amniotic
eggs, scales on legs, wings, feathers,
endotherms, four chambered heart
Class Mammalia: milk from mammary
glands, hair, endotherms, four
chambered heart, large brains, teeth
Mammalian Subdivisions
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Monotremes: egg laying mammals
(i.e. platypuses and spiny anteaters)
Marsupials: born early, complete
embryonic development in a pouch
(i.e. kangaroos and opossums)
Placental mammals (eutherians): long
pregnancy, fetus develops in the
uterus (i.e. dogs and humans)