Transcript Document

Chapter 31: Fishes
Gopher RockFish eating
a small octopus.
Photographed at Bluefish
Cove, Point Lobos State
Reserve, CA
Gopher RockFish,
Sebastes carnatus
“Let the water teem with living creatures…”
biology ~ mr .e
genesis 1:28
fishes
toasted.”
fishes
Sometimes the symbol contains the Greek word for fish,
"ichthus". What's really cool is that this word forms an acronym for
"Jesus Christ, Son of God, Savior" as the following table demonstrates:
Greek letter
Ι (iota)
Χ (chi)
Θ (theta)
Υ (upsilon)
Σ (sigma)
greek word
Iesous
Christos
Theos
Huios
Soter
english word
Jesus
Christ
God
Son
Savior
A somewhat simplified version…
fishes
KINGDOM ANIMALIA:
Major Characteristics of Phylum Chordata
1.Bilateral symmetry; segmented body; three germ layers; welldeveloped coelom.
2.Notochord (a skeletal rod) present at some stage in life cycle.
3.Single, dorsal, tubular nerve cord; anterior end of cord usually
enlarged to form brain.
4.Pharyngeal gill slits present at some stage in life cycle.
5 wksstage but
5.Postanal tail, usually projecting beyond theHuman;
anus at some
may or may not persist.
6.Segmented muscles in an unsegmented trunk.
7.Ventral heart, with dorsal and ventral blood vessels; closed blood
system.
8.Complete digestive system.
9.A cartilaginous or bony endoskeleton present in the majority of
members (vertebrates).
fishes
Subgroups of Chordates:
•Subphylum Urochordata - "Tail Cord." There are approximately
1500 described species of these marine living chordates. They are
commonly called tunicates because of the tough, nonliving tunic that
surrounds the animal.
•The swimming larvae resemble
tadpoles and possess all of the
four key chordate
characteristics. As sessile adults
they lose the notochord and the
tail, their dorsal hollow nerve cord
becomes reduced, but they retain
the pharyngeal gill slits.
Example: tunicates, sea squirts
fishes
•Subphylum Cephalochordata - "Head Cord." There are only 25
species described in this subphylum of marine lancelets. They are all
small, slender, laterally compressed, translucent animals. These
simple animals are often used as a textbook example to represent the
four key chordate characteristics.
•Once considered to be the
ancestor of the chordates,
they are still believed to
more closely resemble the
earliest prevertebrates than
any other animal known.
Examples: Amphioxus (the
lancelets)
Today, amphioxus may be extremely
common in shallow sandy environments: at
Discovery Bay, Jamaica, up to five thousand
individuals per square meter of sand have
been reported. In some parts of the world,
amphioxus are eaten by humans or by
domestic animals; they are important food
items in some parts of Asia, where they are
commercially harvested.
fishes
•Subphylum Vertebrata - "Backboned." This is the largest and
most diverse subphylum of chordates whose nature is characterized
by the basic adaptations of the living endoskeleton, efficient
respiration, advanced nervous system, and paired limbs.
•This group is divided into
those without jaws and those
with jawed mouths. This
course will take a close look at
this subphylum…
Examples: lampreys, sharks,
fish, frogs, snakes, pigeons,
pigs…
fishes
KINGDOM ANIMALIA:
Phylum Chordata : 4 characteristics
Subphylum Urochordata
Subphylum Cephalochordata
1.
Embryonic notochord
2.
Hollow dorsal nerve cord
3.
Pharyngeal slits
4.
Muscular post-anal tail
Subphylum Vertebrata
Class Agnatha (hagfishes & lamprey)
Class Chondrichthyes (sharks, rays, skates, chimeras)
Class Osteichthes (bony fishes like perch, bass, seahorse)
Class Actinista (coelacanths)
Class Amphibia (frogs, toads, salamanders)
Class Reptilia (turtles, tortoises, snakes, lizards, crocidilians)
Class Aves (birds)
Class Mammalia (mammals)
fishes
Key features: Class Agnatha: “without jaws”
•notochord persist
•jawless vertebrates
throughout life
•cartilaginous skeleton
•lack paired appendages
•gills
lampreys
and
hagfishes
Info from excite.sfu
fishes
Defending the maligned hagfish
The hagfish is one of the most despised creatures in the ocean. Its very name inspires
disgust. But does the hagfish deserve its reputation? Maybe it is time to stand up for a fish
that can't stand up for itself. Let's look at the charges against the poor hag.
Charge 1: hagfish are repulsive.
The hagfish may
not win any beauty
contests, but it does
have a kind of
elegant simplicity.
It does not look like
much more than a
swimming tube. Its
mouth is a fleshy
funnel with some
horny barbs around
it.
What really disgusts
people is the hagfish's
behaviour. It is an ocean
vulture, feeding off
wounded and dead
animals by entering into
any available opening
and eating from the
inside out. You don't
want to think about that
for too long.
What's more, the
hagfish has the
remarkable ability to
defend itself by
emitting an incredible
slime when it is
touched. The slime
comes from glands
along the fish's sides,
and it comes out almost
like runny plastic.
Within seconds, a
hagfish can produce a
gallon of the goop, and
slip away from
predators.
If a hagfish seems
repulsive, think about
what the environment
would be without
them. They perform
an important function
by keeping the ocean
clean. All of those
rotting carcasses
would not make the
waters very healthy
Charge 2: hagfish are primitive.
fishes
The hagfish has not
changed for millions of
years, but that's a virtue. It
is so well adapted to its
environment that it does
not need to "improve."
You might say that it is
perfect already.
Charge 3: hagfish are stupid.
How smart does any fish have to
be? Consider this: if you manage
to grab onto a hagfish (in spite
of all of the slime) and hold on
tight, it will tie itself into a knot
and tighten the knot until it pulls
itself out of your grip. Stupid?
Charge 4: hagfish are useless.
In fact, hagfish are often used
in research. They even have
some commercial value. In
recent years, tons of the lowly
hag have been turned into "eel
skin" wallets and belts. Once
again, humans have found a
way to profit from nature, but
whenever we do that, there is a
price to pay. What will happen
to the marine environment if we
remove the "repulsive,
primitive, stupid" hagfish?
On the culinary front…
fishes
…the slime is a sugar and protein solution that coagulates
when it's secreted into water, forming a slime that is similar
in texture and chemical composition to egg whites....
Hagfish-Slime Cheddar-Gruyere Scones
4 cups all-purpose flour
2 tablespoons baking powder
4 teaspoons sugar
1/2 teaspoon salt
1 cup (two sticks) chilled unsalted butter,
cut into 1/2-inch cubes
2 cups (packed) coarsely grated extra-sharp
yellow cheddar cheese (about 9 ounces), or
a mix of 6 ounces cheddar and 3 ounces
gruyere.
1-1/2 cups chilled heavy whipping cream
6 tablespoons hagfish slime
Preheat oven to 375F
Serve warm or at room temperature. The scones
will stand for about 8 hours. Do not refrigerate.
If you want to reheat them, warm them in a
350F oven for about 5 minutes.From a real
culinary perspective, I sort of doubt that the
pure egg-slime substitution works terribly
effectively, since about 1/3 of an egg's mass is
the yolk, which contributes texturally since it's
both pure fat and it holds air marvelously (it's a
born emulsifier). So maybe this would work
better with 4 ounces of hagfish slime and two
egg yolks. Or you could probably replace the
yolks with butter... or cook up some hagfish and
render the fat, if you want the truly authentic
version.
lampreys
fishes
Mouth
(above);
two on trout
(left)
Lampreys begin life as
burrowing freshwater larva.
At this stage (not pictured),
they are toothless, have
rudimentary eyes, and feed on
microorganisms. This larval
stage can last five to seven
years and hence was
originally thought to be an
independent organism
Life Cycle
fishes
After these five to seven years, they
transform into adults in a
metamorphosis which is at least as
radical as that seen in amphibians, and
which involves a radical rearrangement
of internal organs, development of eyes
and transformation from a muddwelling filter feeder into an efficient
swimming predator, which typically
moves into the sea to begin a
predatory/parasitic life, attaching to a
fish by their mouths and feeding on the
blood and tissues of the host. In most
species this phase lasts about 18
months. Whether lampreys are
predators or parasites is a blurred
question.
External Anatomy
fishes
An adult
lamprey
(below)
Opens to
blind sacs
fishes
Class Chondrichthyes: “cartilaginous fishes”
(sharks, rays, skates, chimeras)
Key features:
• cartilaginous skeleton
• notochord replaced by vertebral column
• paired appendages
• jaws
• respiratory gills; NO swim bladders
• internal fertilization
• acute senses (esp. lateral line system)
Dermal denticles from in front
of and a bit below the first
dorsal fin of a whale shark
fishes
great
white
shark
bull shark
Class Chondrichthyes:
sharks
mako shark
blue shark
Class Chondrichthyes:
Skates & rays
Atlantic
stingray
fishes
Ocellated river stingray
Blue spotted
fantail ray
Tampa Bay Ray
Southern stingray
Manta ray
fishes
Q: My Gramma lets me use her computer to learn. Can you help
me understand how Rays and Skates are different please?
A. Skates and rays are very closely related animals. Both are in the
Class Chondrichthyes. These animals are both in the Order
Rajiformes, which includes the sharks, skates and rays. All of these
animals share several similar anatomical structures: Rays typically
have long slender tails that may have a stinger (there are
exceptions), whereas skates generally have a broader, well
developed tail.
Overall, these organisms are remarkably similar, and are only
differentiated at the Family level of classification. Rays comprise
the Torpedinidae and the Dasyatidae, the skates make up the
Family Rajidae. There are differences in the egg cases of these
animals, the numbers of embryos present in the egg cases and
differences in the developmental process as well.
Visually, the animals are hard to distinguish.
External anatomy
fishes
Representative species:
Atlantic Sharpnose Shark
Rhizoprionodon terraenovae
Heterocercal tail
Cloacal vent b/w
Lateral view
fishes
Ventral view
Key features common
to all sharks:
fishes
Fusiform Shape
When engineers came up with the shape of a DC-9 airplane, they were
thinking about the fastest way to travel using the least amount of energy.
If you compare the DC-9 to a shark, you will see that their shapes are
amazingly similar. They both have round bodies tapering off at both
ends. This shape allows the plane to glide through the air, and the shark
to glide through the water, without using up all their fuel before they get
where they want to go.
Why?
This shape minimizes drag… (remember, water & air are
both fluids!)
Fins
fishes
Sharks, as all fish, use their body and tail in a side to side motion to
move through the water. Shark fins are rigid not flexible, and are
supported by rods made of cartilage. Sharks have five different kinds of
fins.
1. Paired pectoral fins lift the shark as it swims.
2. Paired pelvic fins stabilize the shark. (prevent
rolling & provide diving planes)
3. One or two dorsal fins also stabilize the shark.
In some species, dorsal fins have spines.
4. Not all sharks have an anal fin, but it
provides stability for those that do have one.
5. The caudal or tail fin moves the shark forward.
(provides thrust)
“plate-like”
Placoid scales
fishes
Shark skin feels like
sandpaper because it has
small rough placoid scales
(also known as dermal
denticles). As a result, it is
often dried and used as a
leather product or
sandpaper. Placoid scales
consist of a basal bony plate
buried within the skin and a
raised portion that is
exposed. Dermal denticles
are homologous in structure
to teeth.
A regular catfish has a very
sleek, black skin - no
scales, that's why you have
to skin a catfish, not scale it
(that's where the old saying
"more than one way to skin a
cat" comes from, not from
killing off the barn cats).
spiny dogfish denticles (180X)
Ampullae of Lorenzini
The ampullae of Lorenzini are
small vesicles and pores that
form part of an extensive
subcutaneous sensory network
system. These are found
around the head of the shark
and are visible to the naked
eye.
They appear as dark
spots in the photo of a
porbeagle shark head
(right). The ampullae detect
weak magnetic fields/electrical
charges produced by other
fishes, at least over short
ranges. This enables the
shark to locate prey that are
buried in the sand, or orient to
nearby movement.
fishes
Each ampulla is a bundle of sensory cells that are
enervated by several nerve fibers. These fibers
are enclosed in a gel-filled tubule which has a
direct opening to the surface through a pore. The
gel (a glyco-protein based substance) has
electrical properties similar to a semiconductor,
allowing temperature changes to be translated into
electrical information that the shark can use to help
detect temperature gradients
Constant Swimmers
fishes
…their constant movement (albeit lazily at times) provide two things:
1. Oxygen
2. Lift
Bony fish have a gas-filled
swim bladder which enables
them to float in the water,
but sharks have no such
bladder. Since cartilage is
lighter than bone, it helps to
keep a shark from just
sinking to the bottom of the
ocean…
The spiracle is a vestigial first gill slit. It
appears as an opening behind the eye,
do(left).
not have
asAlso,
in the their
spiny gills
dogfish
It is absent
covers
ormuscular
reduced in gill
many
sharks,capable
especially
the
swimming
sharks and is
usually
offast
rhythmic
contraction
(hence
larger and present in sedentary or
they cannot
bottom
dwelling ‘bring
sharks. oxygenIn sharks, the
rich water
tototheir
gills
while
spiracle
is used
provide
oxygenated
blood
directly toso
thethey
eye and
still)…and
mustbrain
through a separate blood vessel. In rays,
always
thelarger
move…
the
spiraclebe
is on
much
and more
developed and is used to actively pump
water over the gills to allow the ray to
breathe while buried in the sand
Razor-sharp teeth
fishes
Shark teeth are not lodged
permanently within the jaw, but are
attached to a membrane known as
a tooth bed. The tooth bed
membrane is similar to a conveyor
belt, moving the rows of teeth
forward as the shark grows, thus
always replacing the older teeth in
front that have become damaged,
fallen out or worn down.
It is not uncommon for shark teeth
to be found lodged in large prey
(such as whale carcasses) or loose
on the ocean floor.
Serrated great
white (left);
smooth-edged
porbeagle
(below)
bony fishes
AWARD: Most diverse
of the vertebrates
Class Osteichthyes: “bony fishes”
(bony fishes like perch, bass, seahorses)
Key features:
• bony skeleton & jaws
• notochord replaced by vertebral column
• paired appendages
• swim bladders
• respiratory gills
• (most) external fertilization
• acute senses (esp. lateral line system)
Representative species:
bony fishes
External anatomy
largemouth bass
bony
INTERNAL ANATOMY
bony
Shapes
bony fishes
Basic shapes
flat
(horizontally
compressed)
vertically
compressed
fusiform
(modified)
eel-like
(serpentine)
round
ribbon
Most osteichthyes are which types?
Shapes continued
bony fishes
VARIATIONS IN BODY FORM
Fish shape has a great bearing on ability to move
through the water.
•A tuna fish which has a fusiform similar to a
torpedo can cruise through the water at very high
speeds.
•The attenuated shape of the eel allows it to
wiggle into small crevices where it hunts prey.
•The depressed shape of the angler fish is
advantageous for its "sit and wait" strategy of
hunting.
•The compressed shape found on many reef fishes
such as the angel fish gives the fish great agility
for movement around the reef and can support
sudden bursts of acceleration.
Fins
bony fishes
paired appendages: pectoral & pelvic fins paired
•Three distinct groups:
1. Lobe-finned fishes
2. Fleshy-finned fishes
3. Ray-finned fishes
bony fishes
•Three distinct groups:
1. Lobe-finned fishes: have fins and bony rays and lobes of bone-less areas
lacking rays. Simple, primitive type of fishes:
The coelacanth is a simple bony, lobe-fin fish which was once thought
to be extinct, but was found living off the coast of south Africa in 1938.
2. Fleshy-finned fishes: Simple bony fishes represented today by only 3 genera;
resemble lobe-fins (have lungs and lobed fins).
Although they have gills and lungs, they cannot survive outside of
water; can come to the surface and gulp air. Another sp. actually can
breathe air for long periods of time; can burrow into mud and form a
cocoon to survive the summer in tropical regions. The medial fins are
fused to make one large, continuous fin.
3. Ray-finned fishes: Largest group of bony fishes (21,000 sp.). Most common
and familiar type of bony fish. Fins entirely composed and supported by rays; no
lobes present.
bony fishes
•Three distinct groups:
1. Lobe-finned fishes
2. Fleshy-finned fishes
3. Ray-finned fishes
bony fishes
bony fishes
The CRM "Deep Release" T-shirt (pictured)
was a unique concept. The shirts that we
sent to the Comoros for the fishermen to
wear actually had the Deep Release kit sewn
onto the back below the diagram, so that it
was available to them while they were
fishing. (We discovered that Comoran
fishermen love T-shirts.)
When they accidentally caught a coelacanth
they could then follow the release procedure
diagram on the back of the shirt to set it
free. More than 100 of these and 400 of the
new more easily produced Type II's have
been sent to the Comoros thanks to
contributors.
bony fishes
bony fishes
Marbled African
Lungfish
South
American
Lungfish
•Three distinct groups:
1. Lobe-finned fishes
2. Fleshy-finned fishes
3. Ray-finned fishes
•While in the water, these fishes
excrete their nitrogenous waste as
ammonia, just as most ray-finned
fishes do. In time of drought, these
animals burrow in the mud and switch
to produce the less toxic nitrogenous
compound urea.
muskellunge
bony fishes
•Three distinct groups:
1. Lobe-finned fishes
2. Fleshy-finned fishes
3. Ray-finned fishes
Tropical tetra
Reef damsel (left)
Types of Scales
bony fishes
plate-shaped
Placoid = isolated in sharks
Primitive = Ganoid = bone and
enamel form a tile mosaicsolid
Rhombic-shaped
Smooth post. margin
Cycloid,
ctenoid =
reduced:
thin, light
weight,
overlapping
Serrated post. margin
Scales continued…
bony fishes
Why are fish slimy?
Fish secrete a type of mucus from their
skin. This slime coating is important because it
1. provides protection against parasites
and diseases,
2. covers wounds to prevent infection and
3. helps fish move through the water
faster (reduces drag)
Some species release toxins in their slime which
ward off attacking creatures while others use their
slime to feed their young.
Distinct Lateral line
“What is it?”
“it’s something
electrical…”
“it helps protect from
predators…”
fishes
Distinct Lateral line
bony fishes
Sometimes referred to as the
Lateral lines are composed of
“sense
of distant
touch,”
lateral
neuromasts
(hair cells
surrounded
HOW
DOES
IT changes
WORK?
lines
convert
subtle
in
by a protruding
jelly-like
cupula)
water
electrical
that usually
lie atinto
the
bottom
ofits
a own pressure wave in the water that is
Apressure
swimming
fish
sets up
pulsesdetectable
similar
to
way
our
visible
pit
or groove.
These
hair
bythe
the
lateral
line systems of other fish. It also sets up a bow
cells
theresponds
same
sensory
cells
inner—
ear
sound
wave
in
front
oftoitself,
the pressure of which is higher than that of the
found
inRunning
all flow
vertebrate
ears
— The differences in the two pressures are
wave
along
its sides.
waves.
lengthwise
convert
mechanical
energy
intoandline system. As the fish approaches an
own
lateral
downregistered
each
sidebyofits
the
body
electrical
energy
when
moved.
object,
such
as a pressurerock
or the glass wall of an aquarium, the pressure
over the
head,
these
waves
around
itstheir
body are distorted, and these changes are quickly
sensing
organs
help
detected by the lateral line system, enabling the fish to swerve or to take
owners
avoidauditory
collisions,
“Presumably,
and lateral
other suitable
action.
participate
schooling
line pathwaysinevolved
in close
behavior,
to water
associationorient
since they
share
currents,
elude predators, and
many
features.”
detect prey.
Distinct Lateral line
bony fishes
Do we have a sixth sense?
Humans have five senses; sight, hearing, feel, taste, and smell. Since
mammals don't have a lateral line system, it's very difficult, maybe
impossible, to convey just what it must be like to have this added ability.
After all, could you really convey what sight is like to someone who has
never been able to see? But maybe we can provide an approximation of
what the lateral line system is like by trying one particular activity.
For this activity, you'll need to blindfold a person
and have them move within a room. Make sure
there is some open space along one wall and then
blindfold a willing subject. The object of this
activity will be for the blindfolded person to try
and determine when he/she is really close to a wall
without touching - they can use other senses other
than eyesight.
Is this a fish? 
Cuttlefish lateral lines
Relationship to
motion
bony fishes
Two design features distinguish the bony fishes from sharks:
1. Swim bladder
Bony fish have swim bladders to help
them maintain buoyancy in the water.
The swim bladder is a sac inside the
abdomen that contains gas. This sac
may be open or closed to the gut. If
you have ever caught a fish and
wondered why its eyes are bulging out
of its head, it is because the air in the
swim bladder has expanded and is
pushing against the back of the eye.
Oxygen is the largest percentage of
gas in the bladder; nitrogen and
carbon dioxide also fill in passively.
2. Pharyngeal design
Muscles cause the fish’s operculae to
open & close in concert with their
mouth, thereby drawing fresh water in
their mouth, over their gills and
expelling it back out through their
operculae—even when stationary!
Gill ventilation
bony fishes
How do fish ventilate their gills? Fish must pass new water over their gills continuously
to keep a supply of oxygenated water available for diffusion. Fishes use two different
methods for keeping a continuous supply of new water available, one is very simple and
the other complex.
Ram Ventilation: Swim
through the water and open
your mouth. Very simple,
but the fish must swim
continuously in order to
breathe, not so simple.
Opercular pump: an elaborate double pump
method in which the fish opens and closes its
various seals, covers, and mouth to keep water
flowing over its lamellae.
How Fish Breathe
bony fishes
The water surrounding a fish contains a small percentage of dissolved oxygen. In the surface
waters there can be about 5 ml. of oxygen per liter of water. This is much less than the 210 ml. of
oxygen per liter of air that we breath, so the fish must use a special system for concentrating the
oxygen in the water to meet their physiological needs.
The circulation of blood in fish is simple. The heart
only has two chambers, in contrast to our heart
which has four. This is because the fish heart only
pumps blood in one direction.
The blood enters the heart through a vein
and exits through a vein on its way to the
gills. In the gills, the blood picks up
oxygen from the surrounding water and
leaves the gills in arteries, which go to
the body. The oxygen is used in the body
and goes back to the heart. A very simple
closed-circle circulatory system.
How Fish Breathe
bony fishes
The gills: the gills are composed of a gill arch (which gives the gill rigid support),
gill filaments (always paired), and secondary lamellae, (where gas exchange takes
place). Which direction seems beneficial—and likely? Why?
Which two fluids interact to
ensure that fish breathe?
Does flow direction matter ?
How Fish Breathe
bony fishes
•The blood flows thorough the gill filaments and secondary lamellae in the opposite direction from the
water passing the gills. (countercurrent) This is very important for getting all of the available oxygen out
of the water and into the blood.
•If the blood flowed concurrently (parallel flow), then the blood would only be able to get half of the
available oxygen from the water. The blood and water would reach an equilibrium in oxygen content and
diffusion would no longer take place.
•By having the blood flow in the opposite direction, the gradient is always such that the water has more
available oxygen than the blood, and oxygen diffusion continues to take place after the blood has
acquired more than 50% of the water's oxygen content. The countercurrent exchange system gives fish
an 80-90% efficiency in acquiring oxygen.
How Fish Breathe
bony fishes
•When fish are taken out of the water, they
suffocate. This is not because they cannot
breathe the oxygen available in the air, but
because their gill arches collapse and there
is not enough surface area for diffusion to
take place. There are actually some fish
that can survive out of the water, such as
the walking catfish (which have modified
lamellae allowing them to breathe air).
triggerfish
butterfly fish
It is possible for a fish to
suffocate in the water. This could
happen when the oxygen in the
water has been used up by
another biotic source such as
bacteria decomposing a red tide.
Swimming
bony fishes
The
provide
power
for swimming
constitute
up to
80%
of the
Themuscles
density of
waterthe
makes
it very
difficult toand
move
in, but fish
can
move
veryfish
itself.
The muscles
are arranged in multiple directions (myomeres) that allow the
smoothly
and quickly.
fish to move in any direction. A sinusoidal wave passes down from the head to the
A swimming
fish is relying
on its
framework,
muscles
forthe
tail.
The fins provide
a platform
to skeleton
exert thefor
thrust
from the its
muscles
onto
power, and its fins for thrust and direction.
water.
In regards to physics, the
skeleton of a fish is
radically complex.
The skull acts as a
fulcrum, the relatively
stable part of the fish.
The vertebral column
acts as levers that operate
for the movement of the
fish.
Diagram of forces when
a fish swims.
Thrust- force in animal's
direction
Lift- force opposite in
right angles to the thrust
Drag- force opposite the
direction of movement
** All lift forces cancel
out over one complete tail
stroke
bony fishes
Drag
Drag is minimized by the streamlined shape of the fish and a special slime
fishes excrete from their skin that minimizes frictional drag and maintains
laminar (smooth) flow of water past the fish
When:
thrust > drag = swimming!
Slime is secreted from cells in the very outside layer of the skin. In some
cases, the placement of these slime-producing cells determines what species
of fish it is. The cells produce what is called a glyco-protein, which is then
mixed with the water making the slimy mucus.
Two types of
Swimming
bony fishes
Defined by their method of living, and reflected in their physiology.
•Cruisers: These are the fish that swim almost continuously in search for
food, such as the tuna. Red Muscle- richly vascularized (blood-carrying
capacity), rich in myoglobin (oxygen holder and transferor into the muscles
active sites) * able to sustain continuous aerobic movement.
•Fast: tend to have rigid bodies with less lateral movement (tail mostly)
•Slow: tend to be more flexible with exaggerated lateral motion
•Burst Swimmers: These fish usually stay relatively in the same place such
as most reef fish.
Schooling: “shoals”
School of Blacksmiths in Channel Islands
Photographed at Wilson's Rock (Metridium
Wall), Channel Islands
Everyone has heard of a school of fish, an aggregation of fish hanging out together;
Blacksmiths,
punctipinnis
but why, they are obviously not learning reading, writing,
and Chromis
arithmetic.
Schools of
fish may be either polarized (with all the fish facing the same direction) or non
polarized (all going every which way)
Advantages?
1. Antipredator: by hanging out with other fish, each individual fish may gain an
advantage in not being eaten by other fish.
A. Confusion effect. A large school of fish may be able to confuse a
potential predator into thinking that the school is actually a much larger organism.
B. Dilution affect. If a fish hangs out with a lot of other fish and a
predator does come around, the predator must usually select one prey
item. With so many choices, the chances are that it will not be you. This is known
as the 'selfish herd'.
C. Predator detection. A bunch of fish has many times the eyes and other senses
than a solitary fish; so a school of fish may be better at detecting predators. But a
school may also attract predators due to its large size.
Schooling:
Advantages (con’t)
2. Spawning Aggregation: Many fish species form schools only when it comes time to
mate. They will form a huge school and release their eggs and sperm in mass quantities.
Releasing a massive onslaught of fertilized eggs in the water may be advantages over a
solitary egg, because a massive onslaught may be enough to overwhelm the egg predators.
The predators will eat as many as they can, but some eggs will inevitably survive.
3. Enhanced Foraging: A school of fish may have better abilities to acquire food. With
many more eyes to detect food, many more meals may be found; but there would also be
many more mouths to feed. By working as a team, the school may be able to take larger
food items than any one individual could manage to capture.
4. Migration: The migration abilities of fish in schools may possibly be enhanced due
to better navigation, etc. Hydrodynamic efficiency: Due to the complex hydrodynamic
properties of water (properties the fish probably discovered only by accident), a fish may
gain a swimming advantage by being in a school. The slipstream from the fish ahead of it
may make it easier to pass through the water. Good for all the fish except for the ones in
front.
Schooling:
Finding Nemo School of Fish
Schooling:
bony fishes
A school of Blue Rockfish
congregates around some tattered
kelp stipes.
Photographed at Pescadero
Pinnacles, Carmel, CA, Monterey
Bay National Marine Sanctuary.
Blue Rockfish, Sebastes mystinus
 Can you easliy
distinguish between
leaf & fish?
Modes of Reproduction
fishes
Hammerhead pulled
from dead mother Whitetail pup
With their gills exposed to sea water, all marine fishes are faced with the problem of conserving
Skate egg
body water in a strongly hypertonic environment. Sea water is about 3.5% salt, over 3 times that
of vertebrate blood. The cartilaginous fishes solve the problem by maintaining such a high
concentration of urea in their blood (2.5% — far higher than the 0.02% of other vertebrates) that
it is in osmotic balance with — that is, is isotonic to — sea water.
This ability develops late in embryology, so the eggs of these species cannot simply be released
in the sea. Two solutions are used:
•Retain the eggs
•Enclose the egg
and embryos
in an impervious
within the mother's
case filled with
body until they are
vs.
isotonic fluid
capable of coping
before depositing
with the marine
it in the sea.
environment.
oviparous
ovoviviparous; viviparous
Both these solutions require internal fertilization, and, according to the neo-Darwinian
phylogenetic tree, the cartilaginous fishes were the first vertebrates to develop this. The
pelvic fins of the male are modified for depositing sperm in the reproductive tract of the
female.
fishes
Dwarf puffer
Modes of reproduction:
•Ovoparity-- Lay undeveloped eggs, External
fertilization (90% of bony fish), Internal fertilization
(some sharks and rays)
•Ovoviviparity- Internal development- without direct
maternal nourishment-Advanced at birth (most sharks
and rays)-Larval birth (some scorpeaniforms-rockfish)
•Viviparity- Internal development- direct nourishment
from mother-Fully advanced at birth (some sharks, surf
perches)
Modes of Reproduction
fishes
In fishes, oviparity is most common:
angel
1. the eggs are inexpensive to produce
2. as eggs are in the water, they do not dry out (oxygen, nutrients are not scarce).
+
3. The adult can produce many offspring, which they broadcast into the plankton
column.
4. When the offspring settle out of the plankton, they may be in totally new
environments, allowing for a great area in which the young may survive.
This mode also comes with its disadvantages:
_
1. when born, the fish must first go through a vulnerable larval stage for growth
before they transform into the adult stage. In this larval stage, they must fend for
themselves in obtaining food and avoiding predation.
2. They may not find a suitable environment when they settle out of the plankton
column. The survival of individual eggs is very low, so millions of eggs must be
produced in order for the parent to successfully produce offspring.
Mangrove Rivulus
bony fishes
Hippocampus
abdominalis
Gymnothorax prasinus•The Seahorse belongs to
the Syngnathidae family,
gymno - bare, naked (Greek)
the only group of animals
thorax - chest (Greek) where the male becomes
prasinos - leek green (Greek)
pregnant. When mating,
R. marmoratus is a selffertilizing hermaphrodite that
attains a total length of
approximately 2 inches (~ 50
mm). Hermaphrodites of this
species have a prominent
caudal ocellus and a whitish
border along the anal fin. Pure
females, primary males and
secondary males, have been
observed in the laboratory, but
only males and hermaphrodites
have been observed in natural
populations.
the female Seahorse inserts
her eggs into the male’s
pouch. The male fertilizes
the eggs as they enter his
pouch and carries them for
up to a month before going
into labour for several
hours, giving birth from
anything from 20 to 400
babies!
http://www.youtube.com/w
atch?v=BPlnqckOPdY
•Seahorses
propel
themselves by a
dorsal fin on
their back,
which beats at
around 70 times
per minute.
Color
bony fishes
Fancy Guppies
Your picture (below,
left)shows that your
Good
male
hastank
a big mates
for Fancy
Guppies
abdomen
area,
and
his
abdomen
might
are
Cory Catfish,
deceive you into
Small Tetras such
thinking he's a female.
aswe
Neon
But
knowTetras,
from his
gonopodium
fin that
White Clouds,
he
is a male.
Also, he
Honey
Gourami,
has very bright colors,
Glass
Fish,
and
I have
never Ghost
seen
andwith
African
aShrimp,
female Guppy
such
bright
coloration.
Dwarf
Frogs.
Is it male or female and if it's
female does it look like it's
carrying fry?
bony fishes
bettas
Even though Bettas do
In experiments
well in waters low in
where the labyrinth
dissolved oxygen, that
organ was removed,
does not mean they
the fish died from
require less oxygen than
suffocation even
other fish. Bettas have a
though the water was
special respiratory
saturated with
organ that allows them
oxygen. For this
to breath air directly
reason, Bettas must
from the surface. In fact
have access to the
they inherently must do
water surface to
so.
breath air directly
from the atmosphere.
.
bony fishes
Bettas:growth
Betta egg: 0.03 inches in diameter
One day old fry: 0.1 inch long (The tail doesn't
show at this scale)
One week old: 0.2 inches long.
Two weeks old: 0.25 inches long.
(Starting to show dorsal fins.)
Three weeks old: 0.34 inches long
Four weeks old: 0.45 inches long on average.
Five weeks old: 0.6 inches long. Size ranges from .5
to .75 inches.
Six weeks old: 0.85 inches long. The largest are
over an inch.
As a reference, the line
Seven weeks old: 1.1 inches long.
below is one inch long.
Eight weeks old: 1.3 inches long.
Nine weeks old: 1.55 inches long.
________
Ten weeks old: 1.7 inches long
http://www.youtube.com/watch?v=rK0m_awMOWQ&feature=related
Eleven weeks old: 1.9 inches long
©Wayne schmidt
Common tank fishes
bony fishes
neons
Dwarf gourami
Convict pair
“P. pulcher is probably the
most well established west
african cichlid in the
international hobby today. I
suspect that it is the most
available dwarf cichlid of
any type.” Juan Azas
closer
view of the
This picture
female
Convict
shows hundreds
carefully
watching
of eggs that
were
over
her
babies
laid
on the rock.
african cichlid
Common tank fishes
Plecostimus
bony fishes
neons
Black molly
Zebra
Pearl
danio
gourami
goby
Fantail goldfish
Common tank fishes
Dwarf Puffers
bony fishes
“These tiny guys are SO cute
and playful. They're
freshwater fish, and do not
require a brackish
environment. They love live
and frozen meaty foods, but
reject flake. They are too
small for krill, so I stick to
brine shrimp, blood worms,
baby snails and the like. They
are very curious and like to
come and see what you're
doing when they notice
you're in the room. They are
VERY responsive to their
owners and really wonderful
in small tanks. I highly
recommend these fish.
They're so cute you'll wish
you could literally SQUEEZE
them!”
Contributed by Shawna
A strange transformation
bony fishes
Larval stage
Sexually maturity is reached
at age 3. Spawning takes
place during the fall and
winter while the fish are
moving offshore into deeper
water or when they reach
their winter location. The
eggs, which float near the
surface, hatch in 3 or 4 days
to produce larvae shaped
more like conventional fish
than flatfish. Water currents
carry newly hatched flounder
into the estuaries and
sounds, where they undergo
a transformation in shape
and become bottom dwellers.
THE SEXUAL PARASITE
fishes
Thousands
of feet below the
Finding a mate in the dark depths of the
surface,
waters
of So
thewhat
ocean
ocean is athe
pretty
tough job!
does are
a male anglerfish do when he finds a
cold,
still, and dark. Almost no
mate? He never lets her go! The male
sunlight
can penetrate
such
lives as a parasite
on the body
of thedepths,
much larger female, taking his food from
and
the water temperature hovers
her bloodstream. Their bodies fuse
near
freezing.
The
conditions
together,
forming a
sort harsh
of two body
Although this arrangement
ofhermaphrodite.
the
abyss
houses
some of the
primarily benefits the male, it also frees
most
nightmarish
bizarre-looking
both sexes
from constantly
seeking out
new breeding partners whenever it is time
creatures
on Earth. Here there is a
to mate. How do they find each other in
need
for a light that will help
the darkness?
organisms
find
their
through
Although at one
time
it wasway
thought
that
each lure was designed only to attract
the
dark murky waters, this light
special prey, it now appears that the
that
is produced
fromaamale
cool
unique
shape also attracts
of the
same species who recognizes his future
chemical
reaction, unlike sunlight
mate by her lure.
(which is thermal) or electrical
light, is known as bioluminescence.
Aggressive fish
Jack dempsey
bony fishes
oscar
Bass & beam
Threespot damsel (salt)
firemouth cichlid
angels
Some you may
have hooked…
Bonytongued
fish
bony fishes
Bluegill; “sunny”
Common carp
Red snapper
grouper
Spotted tilapia
Yellow perch
white catfish
Impact on man
bony
fishes
In the 1860s, sturgeon were
looked at as a nuisance to
anglers and were
Acommercial
large female
has been
deliberately destroyed in
known
to yield 100
pounds
large numbers.
Then,
in the
(45.4
kg)people
of roe,realized
or eggs,that
1870s,
sturgeon
were8 useful
equal
to about
percentfor
of
products
such as:
glue from
her
body weight.
Salted
and
their skeleton; oil from fat;
processed
sturgeon roe is
leather from their tanned
used
to make
caviar
can
skins;
roe (eggs)
forthat
caviar;
cost
to U.S.
$100
perswim
andup
gelatin
from
their
bladder,
used
for liquid
ounce
in the
toniest
clarifyers,injellies
jams.
restaurants
New and
York,
In the 1950s, fish biologists
London,
or Tokyo.
began to study sturgeon
populations and spawning
sites to help protect and
increase their numbers.
Sturgeon roe, weighing
1,122.7 grams, when
converted to caviar will be
worth roughly $2,245.00 at
$56.00 an ounce.
bony fishes
Do fish have
intelligence?
Our observations
in the lab:
• feeder
recognition
• follow finger
•hand feeding
•train TA’s
shark
• cartilaginous
• denticles
• swims; oily liver
• live birth; eggs
bony fishes
Skeleton
Skin
Buoyancy
Reproduction
eel
• bony
• slimy skin
• swim bladder
• Eggs; live birth
To Whom is the coelocanth more closely related?
Circle the features shared by the coelocanth…
fishes
Mouth morphology diversity in fish, sharks, and lampreys.
1. northern anchovy;
2. peacock flounder;
3. white sturgeon;
4. yellow seahorse;
5. Chinese sucker;
6. bobtail snipe eel;
7. secretary blenny;
8. tiger shark;
9. pebbled butterflyfish;
10. blackspotted wrasse;
11. clown triggerfish;
12. swordfish;
13. sockeye salmon;
14. king mackerel;
15. sea lamprey;
16. paddlefish;
17. red-bellied piranha;
18. longnose gar;
19. minnow; 20. catfish;
21. pelican eel;
22. deep sea anglerfish;
23. bicolor parrotfish;
24. green moray
Info & images from
liverpoolmuseums.org
shrimpfish
stonefish
The stonefish exactly copies the
shape and colour of weedcovered coral. The trouble
comes if you stand on him - the
poison inside those painful
spines can kill a human!
Efficient
camouflage
mackerel
leafy sea dragon
monkfish
mackerel
The shark hunts other fish using its
streamlined shape and strong muscles to
achieve amazing speeds through the water.
If it were slower than the fish it eats (like
the mackerel) the shark would go hungry
(although it does eat dead animals as
well).
Fast
cruiser
The shark is not the fastest fish in the sea
though. The sailfish has been timed at a
cool 68 mph (109km/h).
shark
sea horse
Feeding efficiency
frogfish
yellow tang
A good performance from the
frogfish there. Actually, more of
a good wait. It simply sits still,
waiting until its superb
camouflage fools an
unsuspecting fish into coming
too close. Totally efficient
feeding.
Efficient
feeding:
best
return for
E input
coral butterflyfish
barracuda
Mouth-brooding cichlid
Sea horse
What can I do?
The European eel is the
runaway winner, covering up
to 7500km (4660 miles) on the
journey to the Sargasso sea.
That long, smooth muscular
body helps it cover the miles.
European eel
salmon
fishes
the end
fishes
fishes
Leopard Sharks
Triakis semifasciata
Each summer, hundreds of leopard sharks
gather in the waters off La Jolla, California and cruise the shallows.
Harmless to humans, these sharks, which reach five feet in length,
make a beautiful sight for those lucky enough to swim with them.
Quite skittish, they are virtually unapproachable on scuba gear.
Fortunately, they prefer the shallows,
and are most commonly seen in waters 4 to 5 feet deep,
so all that's needed is a mask and snorkel
fishes
marlin
sailfish
fishes