Oncorhynchus mykiss
Rainbow trout
External Anatomy
Tail
Trunk
Head
External Anatomy
Adipose Fin
Caudal or Tail
Anal or Ventral
Fin
Fin
Dorsal Fin
Pelvic Fins
Pectoral Fins
Pectoral
fins:
The caudal
pectoral
actfin
as brakes
and help
the
Caudal
fin: The
finfins
or
tail
is the
biggest
fin.
Itfish turn
Pelvic
fins:
The
pelvic
fins
help
the
fish
move
up
and
down.
Anal,left
adipose
and
dorsal
fins:
finsto
are
usedmoving
for swimming
and right.
provides
the
push
forThese
the trout
start
and alsoand balance.
acts as a rudder for steering through the water.
External Anatomy
Operculum
Eye
Scales
Mouth
Lateral Line
Lateral line: Runs from the head of the fish to the tail. It detects
Eyes:
The
pupilsinhave
afish.
slight
triangle
shape
which
helps
Scales:
Protect
the
They
grow
as
the
fish
grows.
vibrations
or
waves
the
water.
This
helps
keep
the
trout
from
Mouth:
Operculum:
Trout
This
use
is
their
a
hard
mouths
plate
to
that
grab
covers
food
and
the
delicate
feel
things.
gills
the
trout
see
above,
in
front
and
below
its
body.
bumping into things and helps the fish sense danger.
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Eye
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Trout can see things both near and far away. The large pupils let as much light
as possible enter the eye.
Lens
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The lens in the eye moves around and allows fish to focus on objects.
External Anatomy
Nostril or Nare
Teeth
The nare is a
closed sac. It
helps the fish to
smell odors.
Teeth are found along
the upper and lower
jaws. They grasp and
hold onto prey.
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Mouth
Food passes
through the
esophagus to
the stomach.
Gill rakers strain particles out of
the water to keep the gills from
getting clogged and injured.
The tongue has teeth
which help to hold onto
prey.
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Expose Gill Tissue
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Cut off operculum to show the gill.
Gills
Gill filaments
Gill arch
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Water is taken in through the mouth and passes over the gills. The gills take in
oxygen and release carbon dioxide.
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Carefully cut a flap to expose the internal organs.
Internal Anatomy
Stomach
Pyloric caeca
Swim bladder
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Heart
Liver
Gall bladder
Spleen
Kidney
Kidney
Kidney
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The kidney filters waste from the blood stream and also makes blood. Two
canals carry waste from the kidneys to the bladder. From the bladder,
the waste passes to the outside through a hole called the vent.
Swim Bladder
This is an inflated
swim bladder .
The swim bladder is
like a balloon. It
allows the trout to
float and move up and
down in the water. To
fill the swim bladder,
fish gulp and swallow
air. Fish burp to get
air out of the swim
bladder.
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Digestion
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Stomach
Fat
Intestine
Mouth
Path of Digestion
Esop
h ag u
Cardiac stomach
nes
I nt
est
i
Pyloric stomach
Vent
When a trout eats, both food and water enter the mouth. Water is directed
to the gills, and food goes to the esophagus which leads to the stomach. Food
moves through the stomachs into the intestines and is eliminated out the
vent.
Cardiac Stomach
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Digestion of food starts in the cardiac stomach. Acid secreted
by glands activate enzymes that digest protein.
Pyloric Stomach
The pyloric caeca act
like a small intestine.
They release
digestive juices
needed to break
down food and
absorb nutrients into
the blood stream .
Pyloric caeca
Liver
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The liver produces bile which is stored in the gall bladder. Bile
breaks down fat.
Gall Bladder
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The gall bladder is connected to the liver and stores bile made by the
liver.
Spleen
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The spleen makes and stores blood.
Heart and Gills
Compare the location of the heart to the gills.
Why is this important?
Gills
Heart
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Close up of Heart
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Bulbus arteriosus
Atrium
Ventricle
Heart
The heart consists of two
chambers, the atrium that
receives the blood and the
ventricle that pumps the blood
to the body. The blood first
passes through the gills where it
picks up oxygen, then circulates
through the body to the organs
where nutrients, gases and
wastes are exchanged.
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Bulbus arteriosus
Atrium
Ventricle
Brain
Cerebellum
Medulla oblongata
Optic lobes
The brain is the control center
of the fish. All sensory
information is processed by the
brain. Automatic functions (such
as breathing) and higher
behaviors ("Should I eat that
critter ?") happen in the brain.
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