Download Biology II - Angelfire

Chordates
Chapter 30
30-1 The Chordates
What is a chordate? A chordate is an
animal that has, for at least some
stage of its life, a dorsal, hollow
nerve cord; a notochord; pharyngeal
pouches, and a tail that extends
beyond the anus.
30-1 The Chordates
The hollow nerve cord runs along the
dorsal part of the body. Nerves
branch from this cord at regular
intervals and connect to internal
organs, muscles and sense organs.
30-1 The Chordates
Notochord is a long supporting rod
that runs through the body just
below the nerve cord. Most
chordates have a notochord only
when they are embryos.
30-1 The Chordates
Pharyngeal pouches are paired
structures in the throat region. In
some chordates—such as fishes
and amphibians—slits develop that
connect the pharyngeal pouches to
the outside of the body.
30-1 The Chordates
These slits may then develop into gills that
are used for gas exchange.
At some point in their lives, all chordates
have a tail that extends beyond the anus.
The tail can contain bone and
muscle and is used
in swimming by aquatic
species.
30-1 The Chordates
Transverse section of a chick embryo of
forty-five hours’ incubation.
30-1 Most Chordates are Vertebrates
More than 99% of all chordates are
placed in the subphylum Vertebrata
and are called vertebrates. A
vertebrate is a chordate that has a
strong supporting structure known
as a vertebral column or backbone.
30-1 Most Chordates are Vertebrates
In vertebrates, the dorsal,
hollow nerve cord is called
the spinal cord. As a
vertebrate embryo develops,
the front end of the spinal
cord grows into a brain. The
backbone, which replaces the
notochord in most developing
vertebrates, is made of
individual segments called
vertebrae that enclose and
protect the spinal cord.
30-1 Most Chordates are Vertebrates
A vertebrate’s backbone is
part of an endoskeleton,
or internal skeleton. Like
an arthropod’s
exoskeleton, a
vertebrates, endoskeleton
supports and protects the
animal’s body and gives
muscles a place to attach.
30-1 Most Chordates are Vertebrates
A vertebrate’s skeleton
grows as the animal grows
and does not need to be
shed. A vertebrate’s
skeleton is made of living
cells as well as nonliving
material.
30-1 Nonvertebrate Chordates
Tunicates are one
of two groups of
nonvertebrate
chordates.
30-1 Nonvertebrate Chordates
Both are soft-bodied
marine organisms.
Like all chordates,
these animals have
a hollow nerve cord,
a notochord,
pharyngeal pouches
and a tail.
30-1 Nonvertebrate Chordates
Fossil evidence from
the Cambrian
Period places this
divergence at more
than 550 million
years ago.
30-1 Most Chordates are Vertebrates
The two groups of
nonvertebrate
chordates are
tunicates and
lancelets.
30-1 Nonvertebrate Chordates
Tunicates—Filter-feeding
tunicate larva have all
the chordate
characteristics. Adult
tunicates have no
notochord or tail.
Mouth
Pharynx with
gill silts
30-1 Nonvertebrate Chordates
Lancelets—small, fishlike
creates. Live on sandy
ocean bottoms. Adult
has definite head with
mouth. Closed
circulatory system. No
true heart.
Mouth
Pharynx with gill
slits
30-2 Fishes
Fishes are aquatic
vertebrates that
are characterized
by paired fins,
scales, and gills.
30-2 Fishes
Fishes are so varied that
for almost every general
statement there is an
exception. Fins are for
movement, scales for
protection, and gills for
exchanging gases.
30-2 Evolution of Fish
The evolution of jaws and
the evolution of paired
fins were important
developments during
the rise of fishes.
Grouper
30-2 Geologic Timetable
The earth is estimated to be millions
of years old. To help us understand
the order in which life “evolved” we
need to look at the Geologic
Timetable. This timetable outlines
the periods and major events that
occurred during each. (your learning
packet)
30-2 The first fish
The earliest fishes to
appear in the fossil record
were odd-looking jawless
creatures whose bodies
were armored with bony
plates. They lived in the
oceans during the
Cambrian Period, about
510 million years ago.
30-2 The Age of Fishes
During the Ordovician and
Silurian Periods, about
505 to 410 million years
ago, fishes underwent a
major adaptive radiation.
The species emerged
during the Devonian
Period, which is often
called the Age of Fishes.
30-2 Jawless and Paired Fins
Some ancient fishes kept
their bony armor and had a
deeding adaptation that
changed everything. These
fishes had jaws. Jaws are
an extremely useful
adaptation. Jawless fish
were limited to small soft
food that that they filtered
from the water.
30-2 Jawless and Paired Fins
Jaws allowed fish to eat a much wider
variety of foods. Their fins were
attached to girdles—structures of
cartilage or bones that supports the
fins.
Cartilage is a strong tissue that
supports the body and is softer and
more flexible than
bone.
Dunkeleosteus, large armored fish.
30-2 Jawless and Paired Fins
Paired fins gave fishes more control of
their body movement. Tail fins and
powerful muscles gave fishes greater
thrust when swimming. This gave
accuracy and speed. They had the
ability to turn and use jaws in complex
ways.
Dunkeleosteus, large armored fish.
30-2 Modern Fishes
x
30-2 Modern Fishes
x
30-2 Modern Fishes
Two groups:
 Modern sharks and rays—had an
evolved skeleton made of strong,
resilient cartilage.
 Bony fish—evolved skeletons—
true bones. Lobe-finned fishes—
had fleshy fins.
30-2 Modern Fishes
A fish must overcome inertia, or the
resistance to motion, to move
through water. Most of this
resistance is in the form of drag,
which is caused by the friction of
water as it flows over the body of
the fish. Drag is also caused by
the backward pull of the eddies of
water that form behind the fish’s
tail.
30-2 Modern Fishes
If the fish is streamlined, the water
flowing past both sides of the fish
meets and blends together,
producing less turbulence and
less drag.
30-2 Modern Fishes
Primitive fishes had asymmetrical
tails in which the vertebral column
either pointed upward or
downward as it extended from the
body. When the fins pushed
against the water to propel the fish
forward, the movement was
innefficient.
30-2 Modern Fishes
Modern fishes have tails in which
two symmetrical lobes extend
from the end of the vertebral
column. The forward thrust
provided by this tail is greater and
more evenly distributed along the
length of the body. They can swim
faster and have more control over
their movement.
30-2 Modern Fishes
Modern fishes have tails in which
two symmetrical lobes extend
from the end of the vertebral
column. The forward thrust
provided by this tail is greater and
more evenly distributed along the
length of the body. They can swim
faster and have more control over
their movement.
30-2 Form and Function in Fishes
The oceans of the earth are
extensive and the fishes found in
the them have had to adapt to
survive in the tremendous range
of environments.
Adaptations to aquatic life include
various modes of feeding,
specialized structures for gas
exchange and paired fins for
locomotion.
30-2 Feeding
There are fish who are herbivores,
carnivores, parasites, filter feeders
and detritus feeders.
(detritivore—organisms that feeds
on dead plants and animals.)
From the mouth, food passes
through a short tube called the
esophagus to the stomach where
food is broken down. Then it
travels to the pyloric ceca.
30-2 Respiration
Most fishes exchange gases using
gills located on either side of the
pharynx. The gills are made up of
feathery threadlike structures
called filaments. The filaments
contain a network of fine
capillaries that provide a large
surface area for the exchange of
oxygen and carbon dioxide.
30-2 Respiration
Fish pull the oxygen-rich water through
their mouth, over the gills and then
pushing the oxygen-depleted water
out through openings in the sides of
the pharynx.
Some fishes such as lampreys and
sharks have several gill openings.
Most fish only have a single gill on
each side. This opening is hidden
beneath a protective bony cover
called the operculum.
30-2 Respiration
Some fishes—lungfish—can survive in
oxygen-poor water or in areas where the
water dries up. These fishes have organs
that serve as lungs. A tube brings oxygen
from the air to this organ through the fish’s
mouth. Some lungfishes will suffocate if
not able to reach the surface.
30-2 Circulation
Fish have closed circulatory systems with a
heart that pumps blood around the body in
a single loop—from the heart to the gills,
from the gills to the rest of the body and
back to the heart.
In most fish, the heart consists of four parts:
the sinus venosus, atrium, ventricle, and
bulbus arteriosus. The sinus venosus is a
thin-walled sac that collects blood from the
fish’s veins before it flows to the atrium.
The atrium is a large muscular chamber
that serves a a one-way compartment for
blood.
30-2 Circulation
The ventricle is a thick-walled muscular
chamber where the pumping portion of the
heart is located. It pumps blood to a large
tube called the bulbus arteriosus. This
connects to a large blood vessel called the
aorta where the blood moves to the gills.
30-2 Circulation
The fish heart is
important in
circulation of
oxygen throughout
the fishes body.
30-2 Excretion
Most fishes rid themselves of nitrogenous
wastes in the form of ammonia. Some
wastes diffuse through the gills. Others are
removed by the kidneys that filter wastes
from the blood. Kidneys help fishes control
the amount of water in their bodies. Fishes
in salt water tend to lose water by osmosis.
The kidneys of marine fishes concentrate
wastes and return as much water as
possible to the body.,
30-2 Response
Fishes have well-developed nervous
systems organized around a brain. The
brain has a cerebrum that is responsible
for voluntary activities. The cerebrum’s
primary function is for smell. The optic
lobes process information from the eyes.
The cerebellum coordinates body
movement. The medulla oblongata controls
the functioning of internal organs.
30-2 Response
Most fish have highly developed
sense organs. Almost all fish that
are active in daylight have welldeveloped eyes and color vision
that is at least as good as ours.
Most fish can taste and smell.
They sense movement of water
with their lateral line system.
They use this to sense direction
and motion of prey swimming
nearby. Some fish such as the
electric eel can even generate
electricity.
30-2 Movement
Most fish move by alternately
contracting paired sets of muscles
on either side of the backbone.
This creates a S-shaped curve that
move down the fish’s body. This
force moves fish through the water.
Most fish have an internal, gas-filled
organ called a swim bladder that
adjusts for buoyancy. The swim
bladder lies just below the
backbone.
30-2 Reproduction
The eggs of fishes are fertilized
either externally or internally,
depending upon the species. The
female lays the eggs and the
embryos in the eggs develop and
hatch outside her body.Fishes
whose eggs hatch outside the
mother’s body are oviparous. As
the embryos develop, they obtain
food from the yolk in the egg.
30-2 Reproduction
The salmon are oviparous. In
ovoviviparous species, such as
guppies, the eggs stay in the
mother’s body after internal
fertilization. Each embryo develops
inside and is nourished by the yolk.
The young are born alive.
30-2 Groups of Fishes
All living fishes can be classified into
three groups:
1. Jawless fishes
2. Cartilaginous fishes
3. Bony fish
30-2 Jawless Fishes
Jawless fish have
no true teeth or
jaws. Their
skeletons are
made of fibers
and cartilage.
They lack vertebrae and instead keep
their notochords as adults. There are two
classes: hagfishes and lampreys.
30-2 Sharks and Their Relatives
The class
Chondrichthyes
contains
sharks, rays,
skates and
sawfishes.
There are 350 species of sharks. They
have an enormous number of teeth.
Great White
Hammerhead
Tiger Shark
Tiger Shark
Nurse Shark
Sand Tiger Shark
Sea Dragons
Flying Fish
Angel Fish
30-3 Amphibians
An amphibian is a
vertebrate that
lives in water as
a larva and on
land as an adult,
breathes with
lungs as a adult,
has moist skin
that contains
mucus glands,
and lacks scales
and claws.
30-3 Amphibians
The first amphibian
is guessed to
have come to
land during the
late Devonian
Period, about 360
million years ago.
30-3 Amphibians
Early amphibians
evolved several
adaptations that
helped them live
at least part of
their lives out of
water. Bones in
the limbs and
limb girdles of
amphibians
became stronger,
permitting better
movement.
30-3 Amphibians
Lungs and
breathing
tubes enable
amphibians
to breath air.
The sternum
or
breastbone
formed a
bony shield
to support
and protect
internal
organs.
30-3 Amphibians
The Carboniferous period is
known as the Age of
Amphibians.
30-3 Form and Function
Feeding: Tadpoles are typically filter feeders or
herbivores that graze on algae.
Adult amphibians are almost entirely carnivorous.
They eat practically anything they can catch and
swallow.
From the mouth, food slides down the esophagus into
the stomach. The breakdown of food begins in the
stomach and continues in the small intestines,
where enzymes are made and food absorbed.
There is a liver, pancreas, and gallbladder that aid
in digestion just as in humans. At the end of the
large intestines is a muscular cavity called the
cloaca through which digestive wastes, urine and
eggs or sperm leave the body.
30-3 Amphibian Heart and Kidneys
The amphibian heart has three separate chambers:
left atrium, right atrium and ventricle. The blood
circulates oxygen throughout the frog’s body. When
the atria contract they empty their blood into the
ventricle.
Amphibians have kidneys that filter wastes from the
blood. The excretory product of the kidneys—
urine—travels through tubes called ureters into the
cloaca.
30-3 Group Assignment
Using pages 786-787, find how amphibians:
REPRODUCE
MOVE
RESPOND TO THEIR ENVIRONMENT
What is the nictitating membrane?
What is tympanic membranes?
30-3 Groups of Amphibians
The three groups of amphibians alive today are
salamander, frogs and toads, and caecilians.
SALAMANDERS…
Order Urodela, includes
salamanders and newts
They have long bodies
and tails. Most have 4
legs. They are
carnivores.
30-3 Groups of Amphibians
Caecilians
Legless animals
that live in
water or
burrow in
moist soil or
sediment,
feeding on
small insects
or termites.
30-3 Ecology of Amphibians
Amphibians are
easy prey for
predators since
they have little way
to protect
themselves.
Some release
toxins. Coloration
is their most
effective
protection.
Chapter 30--The End
Next class period
there will be a test
over the chapter
and all homework is
due. Be prepared.
There will be a
penalty for
homework turned in
late.