FISHES
Bio II
Rupp
TYPES OF FISHES
Jawless
 Cartilaginous
 Bony

FISH CHARACTERISTICS
4 hallmarks of
chordates
 Sharks

Lateral line
 Ampullae of Lorenzini


Operculum
Gills
 Tail types
 Scale types
 Fish musculature
 Swimming and the
swim bladder

TAXONOMY
Kingdom Animalia
 Phylum Chordata
 Subphylum Vertebrata

CLASS MYXINI
Hagfish
CLASS CEPHALOSPIDOMORPHI
Lampreys
CLASS CHONDRICHTHYES
Sharks, skates,
and rays
CLASS ACTINOPTERYGII
Ray-finned fishes
CLASS SARCOPTERYGII
Lobe-finned fishes
CHORDATE HALLMARKS

Notochord
Hagfishes and
lampreys keep this
their entire lives
 Made of thick-walled
and fluid-filled cells
pressed closely
together

CHORDATE HALLMARKS

Dorsal hollow nerve
cord
Neural tube formation
 Anterior becomes the
brain

CHORDATE HALLMARKS

Pharyngeal gill
slits/pouches
CHORDATE HALLMARKS
FISH DEFINITION

For our purposes:
A gill-breathing, poikilothermic (cold-blooded),
aquatic vertebrate that possesses fins and a skin that
is usually covered in scales
 Approximately 25,000 species
 Two basic body forms

Agnathans—jawless
 Gnathostomes—jawed

AGNATHANS
Cephalospidomorphi—lampreys—ectoparasites
 Myxini—hagfishes—scavengers

SUPERCLASS GNATHOSTOMES
Cartilaginous fishes
 Class Chondrichthyes—approx. 850 species
 Subclass Elasmobranchii—sharks, skates, and
rays
 Dogfish anatomy

DOGFISH ANATOMY
DOGFISH ANATOMY
DOGFISH ANATOMY
GNATHOSTOME ADAPTATIONS
GNATHOSTOME ADAPTATIONS
GNATHOSTOME REPRODUCTIVE
STRATEGIES
Internal fertilization
 Oviparous—some
species lay eggs
immediately after
fertilization

Ovoviviparous—retain
the developing young
in the uterus and they
are nourished by yolk
sacs
 Viviparous—young
are nourished by a
placenta

SUPERCLASS GNATHOSTOMES
Bony fishes, aka osteichthyes
 Class Actinopterygii—ray-finned fishes
 Class Sarcopterygii—lobe-finned fishes

OSTEICHTHYES ADAPTATIONS
Operculum
 Tail types
 Skin and scales
 Musculature

Swimming
 Swim bladder
 Gills

OPERCULUM
A bony plate attached
to a series of muscles
running over the gills
 Aid in more efficient
respiration
 Bernoulli’s Principle
of Fluid Dynamics

TAIL TYPES
SCALE TYPES
Scales are embedded
in the dermis and
covered by the
epidermis
 Types

Ganoid
 Cycloid
 Ctenoid
 Placoid

GANOID SCALES
CTENIOD SCALES
CYCLOID SCALES
PLACOID SCALES
Typical in sharks
FISH MUSCULATURE
Myomeres-segments
of the muscle
 Myospeta—division
point of the myomeres
 Vertical septum and
horizontal septum of
body cavity

FISH MUSCULATURE




Red muscle or dark
muscle is used in
regular swimming
Red muscle is dark due
to extra myoglobin and
extreme vascularization
Red muscle is often
referred to as the
bloodline
White muscle for escape
response
SWIMMING

Short muscular bodies
and lunate tails for
most efficient
swimming
SWIM BLADDERS
Maintain neutral
buoyancy and depth
control
 Balloon-like structure
 Pulls gas out of the
water to inflate


Two types


Attached to gut—
ancient fishes
Detached from gut—
more modern fishes
Fish without swim
bladders: tuna,
flounder, sharks, deep
ocean fish
 Sharks have a huge
fatty liver to maintain
neutral buoyancy

GILLS
Made of filaments
called lamellae
 Rich with blood
vessels
 Covered by operculum
or gill slits
 Counter current blood
flow of blood and
water increases
efficiency—
demonstration

Gill arches are the
point of attachment
for lamellae
 Gill rakers remove
debris from gills
 Larger gill surface is
often correlated with
higher fish activity
levels
