Ch.33 - Jamestown School District

Unit 9 Chordates
Ch. 33 Comparing Chordates
The Chordate Family Tree
The chordate family tree has its roots in
ancestors that vertebrates share with
tunicates & lancelets
The Chordate Family Tree
Evolutionary Trends in
Over the course of evolution, the
appearance of new adaptations (jaws &
paired appendages) has launched
adaptive radiations in chordate groups
Adaptive radiation - the rapid
diversification of species as they adapt
to new conditions
Evolutionary Trends in
A rapid increase in the # & diversity of
land vertebrates followed the evolution
of 4 limbs
Chordate Diversity
Body Temperature &
The control of body temperature is
important for maintaining homeostasis
in vertebrates, particularly in habitats
where temperature varies widely with
time of day & with season
Body Temperature &
The internal control of body temperature
allows emperor penguins to live in cold
Antarctic climates, where their feathers
act as insulation
Body Temperature &
Ectotherm - the body temperature is
determined by the temperature of the
environ.; the animals pick up heat from,
or lose heat to, their environ.
Most reptiles, fishes, &
amphibians are ectotherms
Body Temperature &
Endotherm - an animal whose body
temp. is controlled from within; they can
generate & retain heat inside their
Birds & mammals are endotherms
Form & Function in Chordates
The blunt, broad jaws & numerous teeth of
crocodiles help them catch large prey,
even in thick vegetation
Form & Function in Chordates
The digestive system of vertebrates have
organs that are well adapted for different
feeding habits
Form & Function in Chordates
As a general rule, aquatic chordates
(tunicates, fishes, & amphibian larvae) use
gills for respiration
Land vertebrates (adult amphibians,
reptiles, birds, & mammals) use lungs
Form & Function in Chordates
During chordate evolution, the heart
developed chambers & partitions that help
separate oxygen-rich & oxygen-poor blood
traveling in the circulatory system
The heart of fishes have 2 chambers,
amphibians & most reptiles have 3
chambers, & crocodilians, birds, &
mammals have 4 chambers
Form & Function in Chordates
Form & Function in Chordates
Nonvertebrate chordates have a simple
nervous system with a mass of nerve cells
that form a brain
Vertebrates have a more complex brain
with distinct regions, each with a different
Form & Function in Chordates
Form & Function in Chordates
The skeletal & muscular systems support a
vertebrate’s body & make it possible to
control movement
Muscles & ligaments attach the
appendages to the backbone &
help control movement
Form & Function in Chordates
Almost all chordates reproduce sexually
Vertebrate evolution shows a trend from
external to internal fertilization
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