1. Warm-Up
 Write down five different characteristics of fish that
you have observed. Once everyone is finished we will
discuss them as a class.

2. Chapter 11:
Fishes, Amphibians, and
Reptiles
SECTION 2: FISHES

3. A fish is a
vertebrate that lives
in water and uses
fins to move.
Fish live in
water, have
fins, obtain oxygen
through gills, have
scales, and most are
ectotherms.
Fish are the
largest group of
vertebrates; almost Characteristics of Fishes
50%.

4. Fish get oxygen
from water. To get
oxygen, they open
their mouth, let
water in. The water
then goes to the
fish’s gills where it
will take the oxygen
and spread it to the
rest of the fish.
Then the water is
sent out of the
body.
Characteristics of Fishes

5. Once oxygen has
entered the fish’s
gills it will go in a
loop through the
fish’s body until it
has spread all of the
oxygen evenly.
A fish has a closed
circulatory system
like most
vertebrates.
The blood in a
fish goes from the Characteristics of Fishes
gills to the
heart, and back
again.

6. All fish have fins
and these help fish
to swim.
A fin provides a
large surface to
push against the
water; it’s kind of
like an oar.
Each fin has thin
membrane
stretched across
bony supports.
Characteristics of Fishes

7. Most fishes have
external
fertilization. This
means that they lay
eggs outside their
body. Once the eggs
are laid a male fish
will come and
fertilize them by
spreading a cloud
of sperm over them.
Some fishes, like
sharks, have
internal
fertilization. This Characteristics of Fishes
means they carry
their young until
they are born.

8. Fishes have
nervous systems
and sense organs
that help them find
food and avoid
predators.
Fish may have
whiskers that help
them
smell, taste, and
feel. This can help
them find food and
it can help them
know when to avoid Characteristics of Fishes
a dangerous
predator.

9. The major groups
of fishes are jawless
fishes, cartilaginous
fishes, and bony
fishes.
Jawless fishes are
unlike other fishes
since they have no
jaws or scales.
Cartilage is what
makes up a jawless
fishes skeleton.
Hagfishes and
lampreys are the
only kinds of
Jawless Fishes
jawless fishes that
exist today.

10. Cartilaginous
fishes have jaws
and scales. They
also have skeletons
made of cartilage.
Sharks use
currents and
moving to get
oxygen whereas
rays will move less
and get water
through holes
behind their eyes.
Cartilaginous
fishes are usually Cartilaginous Fishes
carnivores.

11. A bony fish has
jaws, scales, a pocket
on each side of the
head that holds the
gills, and a skeleton
made of hard bones.
Bony fish have a
swim bladder which
is an internal gas
filled sac which
helps the fish stay
stable at different
depths in the water.
95% of all fishes
Bony Fishes
are bony fishes.
They can live in
salt and fresh water.

12. Science Humor