Download Unit 9 Chordates - Jamestown Public Schools

Unit 9 Chordates
Ch. 30 Nonvertebrate
Chordates, Fishes, &
Amphibians
What Is a Chordate?

A chordate is an animal that has, for at
least some stage of its life, a dorsal,
hollow nerve cord; a notochord;
pharyngeal pouches; & a tail that extends
beyond the anus
What Is a Chordate?
Notochord - a long supporting rod that
runs through the body just below the
nerve cord
 Pharyngeal pouches - paired structures in
the throat region, used to help in gas
exchange

Most Chordates Are Vertebrates

Vertebrae - individual segments that make
up the backbone
Nonvertebrate Chordates
The 2 groups of nonvertebrate chordates
are tunicates & lancelets
 Both are soft-bodied marine organisms
 Tunicates are often called sea squirts
because of the stream of water they eject

Nonvertebrate Chordates

Lancelets are small nonvertebrate
chordates that often live with their bodies
1/2 buried in sand
What Is a Fish?

Fishes are aquatic vertebrates; most
fishes have paired fins, scales, & gills
Evolution of Fishes

The evolution of jaws & the evolution of
paired fins were important developments
during the rise of fishes
Form & Function in Fishes

Adaptations to aquatic life include various
modes of feeding, specialized structures
for gas exchange, & paired fins for
locomotion
Groups of Fishes

When you consider their basic internal
structure, all living fishes can be classified
into 3 groups: jawless fishes, cartilaginous
fishes, & bony fishes
Diversity of Ray-Finned Fishes
Ecology of Fishes

Fishes are important source of food for
many organisms
What Is an Amphibian?

An amphibian is a vertebrate that,
typically, lives in water as a larva & on
land as an adult, breathes with lungs as
an adult, has moist skin that contains
mucous glands, & lacks scales & claws
Evolution of Amphibians
Early amphibians evolved several
adaptations that helped them live at least
part of their lives out of water
 Bones in the limbs of amphibians became
stronger, permitting
more efficient
movement

Evolution of Amphibians
Lungs & breathing tubes enabled them to
breathe air
 The sternum, or breastbone, formed a
bony shield to support & protect internal
organs, especially the lungs

Form & Function in Amphibians

Tadpoles are filter feeders,
adult amphibians are
almost entirely carnivorous
Form & Function in Amphibians
An amphibian’s heart has 3 chambers, 2
atria & 1 ventricle
 Some wastes diffuse across the skin, but
kidneys remove
most wastes from
bloodstream

Form & Function in Amphibians

An amphibian typically begins its life in
water, then moves on land as an adult
Groups of Amphibians

The 3 groups of amphibians alive today
are salamanders, frogs & toads, &
caecilians
Diversity of Amphibians
Ecology of Amphibians
Some amphibians that release toxins
have brightly colored bodies
 The colors & patterns
serve as a warning to
potential predators
