Section 6.3:
Kingdom Animalia
pg. 182-197
Part 2:
VERTEBRATES
Vertebrates
(5% of Animal Kingdom)
The Phylum
Chordata is the
phylum of vertebrates.
Phylum Chordata
(Chordates)
• Most members of this
phylum are vertebrates
with bony skeletons and
backbones.
• Most common on land &
in water.
• Many fewer chordate
species than invertebrate
species.
Chordate Characteristics
At some stage in their life
cycle, Chordates have:
1. A dorsal nerve cord (nerves
branch to all parts of the
body)
2. A notocord (rod of cartilage
that runs along the dorsal
length of the body)
3. Gill slits in the pharynx
(throat).
An Exception
There are two groups of
invertebrate animals that are
part of the Phylum Chordata.
1. Tunicates
2. Lancelets
They have the three
characteristics of chordates.
Comparing Vertebrate Chordates
The organisms within the
Phylum Chordata are divided
commonly by:
1. The presence of an amnion
(fluid-filled sac around the
embryo).
2. The development of the
lung.
Chordate Respiration
• Fish are the only vertebrates
adapted to live their lives
entirely in water. They
obtain oxygen from the
water through their gills.
• Reptiles, birds & mammals
have lung-base respiratory
systems.
Chordate Circulation
There are three types of
circulatory pathways among
vertebrates.
1. Mammals, birds, crocodiles
2. Amphibians & most reptiles
3. Fishes
*** See and know Figure 6.25 on
page 193.
Chordate Reproduction
There are two main methods of fertilization in
vertebrates:
1. External
2. Internal
External Fertilization
• The egg & sperm meet outside the body.
• Ex. Sharks, frogs
Internal Fertilization
• The egg & sperm meet inside
the body
• Ex. Reptiles, birds, mammals
• Mammals are the only
vertebrates in which the
embryo develops internally!
(Exceptions: Duckbill Platypus
& Kangaroo)
Phylum Chordata
Four Subphyla:
1.
2.
3.
4.
Urochordata (tunicates)
Cephalochordata (lancelets)
Agnatha (jawless fish, i.e. hagfish)
Gnathostomata (jawed chordates)
Subphylum Gnathostomata
(jawed chordates)
• Divided into 6 classes:
1.
2.
3.
4.
5.
6.
Chondrichthyes (cartilaginous fish, i.e. sharks)
Osteichthyes (bony fish)
Amphibia (amphibians)
Reptilia (reptiles)
Aves (birds)
Mammalia (mammals)
*** You should know the class (Table 6.3, page 190)
1. Chondrichthyes
(Cartilaginous Fish)
• Skeleton is made of cartilage instead of bone
• Have 5-7 gill slits but lack gill covers
• Ex. Rays, skates, sharks
2. Osteichthyes
(Bony Fish)
• Most numerous of the vertebrates.
• Skeletons are made of bone.
• Ex. Herring, trout, cod
3. Amphibia
(Amphibians)
• In early stages are gill breathers in water, but
live as air breathing adults on land.
• Have a heart with 3 chambers.
• Ex. Frogs, toads
4. Reptilia
(Reptiles)
• Have better developed lungs
than amphibians.
• Have a rib cage
• Skin is thick and scaly & is
made from keratin (a
protein)
• They shed their skin several
times each year.
• Ex. Lizards & snakes
5. Aves
(Birds)
• Have feathers
• Bones are hallow…..why??
• Ex. Robins, Blue Jays,
Swallows
6. Mammalia
(Mammals)
• Have hair
• Have milk-producing
mammary glands
• Give birth to live young
• Most live on land
• A small number are
adapted to life in the
water (i.e. whales,
dolphins)
One Short Video
• Phylum Chordata “How Stuff Works”
Section 6.3
Review Questions
• Do question #’s 1-6 on page 196.
• Do “A Vertebrate Survey” Worksheet.
Section 6.3
Answers
1. On what basis do biologists distinguish animals
from members of other kingdoms?
They use characteristics such as:
reproduction
motility
digestion
cell type
body form
2. Why is Phylum Arthropoda considered the
most successful animal phylum?
Arthropods have an exoskeleton,
segmentation, a nervous system, and
nutrition-related adaptations that have all
helped them to be successful.
3. What characteristics distinguish chordates
from other animals?
Unlike other animals, chordates have a
notochord.
4. How is the body of a flatworm similar to and
different from the body of a sponge and a
cnidarian?
They are all multicellular. The flatworm has
bilateral symmetry, and the sponge is
asymmetrical while the cnidarian is radial. The
flatworm has a simple nervous system like
cnidarian but sponges do not have tissues or
organs. All three lack a body cavity.
5. Sketch a diagram illustrating the difference
between radial symmetry and bilateral
symmetry in animal bodies.
Ex. A starfish vs. a lobster
6. Construct a simple key that enables you to
differentiate among any four animal phyla.
Answers will vary!!
Chordata = dorsal nerve cord
Arthropoda = jointed appendages
Platyhelminthes = three tissue layers
Cnidaria = two tissue layers