2. • Animals that have a Chordates
backbone are called
vertebrates.
• Vertebrates belong
to phylum chordata
(called chordates)
• Vertebrates make up
largest group of
chordates
3. •Two other groups of chordates are
lancelets and tunicates
•Much simpler than vertebrates (no
backbone or well developed head)
4. Chordate Characteristics
• 1) Have a tail (some only have a tail
during embryo stage)
• 2) Hollow nerve cord —in
vertebrates it is called spinal cord
• 3) Pharyngeal pouch —develop into
gills or other body parts as embryo
matures
• 4) Notocord —stiff but flexible rod
that gives body support
– In most vertebrates, embryo’s
notocord is replaced by a
backbone
5. Vertebrate Characteristics
– Have a backbone (strong
but flexible column of bones
called vertebrae)
– Have well developed head
protected by skull (made of
bone or cartilage)
• Cartilage is tough material that
flexible parts of ears and nose
are made of
– Skeletons of vertebrate
embryos are cartilage and
harden into bone
6. Are Vertebrates
Warm or Cold?
• Birds and
mammals are
endotherms (warm
blooded)
– Use energy
released by
chemical reactions
in the body to stay
warm
7. • Fish, amphibians,
and reptiles are
ectotherms (cold
blooded)
– Depend on their
surroundings to
stay warm
8. Fish Characteristics
• More than 25,000 species
of fish
• All fishes share several
characteristics:
– (1) Born to swim
• use fins to steer, stop,
and balance
• scales are bony
structures that cover
and protect body and
lower friction
9. – (2) Making Sense of the
World
• have senses of vision,
hearing, and smell
• have a lateral line
system (row of sense
organs that detect
water vibrations)
– (3)Underwater Breathing
• use gills to breathe
(organ that removes
oxygen from water)
• gills also remove
carbon dioxide from
the blood
10. – (4) Making More
Fish
• most fish
reproduce by
external
fertilization
• females lay
eggs in water
and male
drops sperm
on them
11. Kinds of Fishes
• Three classes of fishes still
living today:
– (1) Jawless fishes
• first fishes (have been
around for half a billion
years)
• Two kinds: hagfish and
lampreys
• Smooth, slimy skin and
round, jawless mouth
• No backbone, but does
by a skull, brain, and
eyes
12. Cartilaginous Fishes
– (2) Cartilaginous Fishes
• skeleton never changes to
bone; stays cartilage
• have fully functional jaws
• strong swimmers and expert
predators
• excellent senses of sight and
smell
• to stay afloat, they store a lot
of oil in their liver, which
helps them be buoyant
• Examples: skates, stingray,
sharks
13. Bony Fishes
– (3) Bony Fishes
• largest class of fish (95%
of all fishes are bony
fishes)
• very different from other
fishes—skeleton made of
bone and body covered by
bony scales
• Unlike other fishes, they
can rest in one place
without swimming because
they have a swim bladder
(gas-filled sac that helps
fish be more buoyant)
14. • Two main groups:
ray-finned and
lobe-finned
– Ray finned:
eels, herrings,
trout, minnows,
perch
– Lobe finned:
lungfishes
