Fin Location
Body Types
Spiny-rayed fish
Soft-rayed fish
Anal Fin
 The anal fin stabilizes
fish while swimming
 It is located on the
ventral side of the fish
near the tail (posterior)
Pectoral Fins
 Pectoral fins allow fish
to make sudden side-toside direction changes
 Can also act as a brake to
slow swimming speed
 Located on the lateral
sides of fish
Pelvic Fins
 Stabilizes fish while
swimming and allows for
up and down movement
 Located on the bottom
of the fish (ventral)
Caudal Fin
 The caudal fin is also
known as the tail
 Functions to propel fish
through the water.
Dorsal Fin(s)
 The dorsal fin helps to
maintain balance while
swimming
 Located on the top of a
fish (dorsal)
Fins
 Spiny-rayed fish have
two dorsal fins
 The first is hard and
spiny, while the other is
soft
Yellow Perch
 Soft-rayed fish have only
one dorsal fin, which is
soft
 Soft-rayed fish also have
a small fin called the
adipose fin by the tail
Brook Trout
Head
 All fish have:
 Two large eyes
 Wide field of vision
 Large mouth used to eat
and breathe
Smell
 In front of the eyes are
two slits called nares

These have the same
function as nostrils in
humans  smelling
 Fish have an incredible
sense of smell
 Trout have a sense of
smell 500 to 800 times
more acute than
humans
Scales
 Nearly all fish have a
layer of scales or bony
plates protecting them
 These scales are covered
in mucus
 This mucus protects the
fish from infection and
also aid in swimming
 This is also why fish are
slippery when you try to
pick them up
Largemouth Bass
Lateral Line
 Line of sensory nerves
extending the length of
the fish
 Along the lateral line
there are pores that
connect through tubes to
the lateral line
Rainbow Trout
Lateral Line Cont.
 Within these tubes are
hairs that vibrate after
stimulation from a
vibration or sound wave
 Allows fish to sense
where vibrations are
coming from
 Also aids in social
behavior such as
schooling
Gill Cover
 Also known as the
operculum
 Hard bony plate that
covers and protects gills
 Similar to how ribs protect
lungs
 Fish can open on
command, causing water
to flush over gills (to
breathe)
 http://www.youtube.com/
watch?v=XEIRlw5rCUk
Fish Internal Anatomy
 Head: fish have a bony
skull that protects the
brain and gills
Fish Internal Anatomy Cont.
 Backbone: Fish are
vertebrates, meaning
they have a backbone
that runs from the head
to the caudal tail
 Spinal Cord: Within the
backbone is the spinal
cord, which connects
the brain to the rest of
the body
Fish Internal Anatomy Cont.
 Brain: Fish have very
tiny brains in
comparison to body size
 Most fish only have
lobes for smell and
sight
 Humans have lobes for
smell, sight, thinking,
and reasoning among
others
Fish Internal Anatomy Cont.
 Ribs: Connected to the
backbone are rows of
ribs, which provide
protection for the
internal organs
 Heart: Unlike human
hearts which have 4
chambers, fish hearts
only have 2 chambers
Fish Internal Anatomy Cont.
 Stomach & Intestines
 Fish have a very basic
digestive system
composed of the
stomach and intestines
 Digest food
 Absorb nutrients
 Push wastes towards
anus
Fish Internal Anatomy Cont.
 The liver filters blood
and removes toxins
 The kidney and urine
bladder both collect
salts and remove waste
from the fish
How Do Fish Breathe?
 Fish can pump water over
their gills using the
operculum (gill cover)
 Gills are lined with blood
vessels with very thin walls
 As the water rushes over
these blood vessels, dissolved
oxygen is diffused from the
water (which has a higher
concentration of D.O.) into
the blood vessels (which has
a lower D.O. concentration)
 As dissolved oxygen enters
the blood vessels, carbon
dioxide is also released
 Some fish require more
oxygen than others
 Trout tend to live in colder
waters, since there is more
oxygen available there
 Largemouth Bass tend to
live in warmer waters,
because they don’t need as
much oxygen
 Cold water = more oxygen
 Warm water = less oxygen
Why Don’t Fish Sink?
 Fish have a specialized
organ called the air
bladder or swim bladder
 This bladder fills with air
and acts like a buoy,
keeping the fish from
sinking
 Helps fish keep an upright
position
 It also helps fish hear by
magnifying sound