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Kindom Animalia,
Phylum Chordata pgs 448- 479
Biology 11
What characteristics set
chordates apart from other phyla?
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At some point in their development all chordates
have these 4 structural characteristics:
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A notochord – becomes the vertebral column in humans
A muscular pharynx with gill slits
A post-anal tail – the coccyx in humans
A hollow dorsal nerve chord – later modified into a brain
and spinal cord
These attributes are always found in the larval
forms or early embryo, although they may be absent
in the adult.
Phylum Chordata is divided
into three subphyla
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Subphylum Urochordata
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Subphylum Cephalochordata
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Example: tinucates
Example: Lancelets
Subphylum Vertebrata
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Examples: fish, amphibians, reptiles, birds,
mammals
Subphylum Urochordata
& Subphylum Cephalochordata
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Represent 5% of chordates
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Aquatic animals that possess the 4
characteristics of chordates.
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No backbone or vertebral column
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Perhaps represent a transient step between
invertebrates and vertebrates
Subphyum Vertebrata
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95% of all chordates
All possess vertebrae, which are hollow
cartilaginous or bony structures that surround the
dorsal nerve cord.
Body plan includes (pg 449):
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Endoskeleton
Large brain with a protective skull
Advanced nervous system
Complex heart and circulatory system
Special outer body cover
One to two pairs of appendages
Large coelom
Subphylum Vetebrata Terminology
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Endotherm – warm blooded animals. Internal
temperature remains constant regardless of
environment. Ex: mammals and birds.
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Ectotherms – cold blooded animals. Body
temperature and metabolic rate change with
the surroundings. Ex: all other vertebrates
including fish, frogs, snakes etc.
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Divided into 3
groups:
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12.2 Fish pg 452
Jawless –Class
Agnatha. Ex:
lampreys, hagfish
Cartilaginous –
Class
Chondrictheys.
Ex: Sharks,
skates, rays
Bony fish - Class
Osteichthyes. Ex:
Salmon, trout,
tuna.
Organ/Structure
Heart
Function
2 chambered heart.
Circulatory System
Blood vessels circulate
oxygenated blood
Respiration
Blood travel to Gills to
be oxygenated
Nervous System
Brain, spinal cord and
peripheral nervous
system.
Reproduction
Separate sexes.
Internal and external
fertilization.
Digestion
One way, developed
system.
Fish Circulatory System
Lobe-finned fish Amphibians
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Lobe-finned fish, have a fleshy lobe at the base of their fins that
is leg-like in appearance. Scientists believe that this fish is the
ancestor of amphibians! Amphibians first appeared 350
million years ago.
*Figure 6, pg 454
 Lobe-finned fish, were thought to be extinct until 1938, when a
coelacanth Latimeria was first captured by chance, they were
known only from the fossil record. Since then several dozen have
been captured and some of their behavior has been filmed using
robotic cameras.
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Latimeria is important because it provides an opportunity to
compare observations from the fossil record with a living animal.
12.3 Amphibians pg 455
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Reproduction
 external fertilization which only
 occurs in aquatic environments.
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Gas exchange
 Young amphibians use gills as they live in aquatic
environments.
 Adult amphibians perform gas exchange through moist
skin, (cutaneous respiration), and poorly developed lungs
with little internal folding and a small surface area as they
are mostly terrestrial.
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Nervous and Digestion Systems – highly developed nervous
and digestive systems.
12.3 Amphibians pg 455
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Circulatory System –
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Inefficient 3 chambered heart where oxygenated
blood and deoxygenated blood are mixed and
then pumped to the body.
12.4 Reptiles pg 457
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Reptiles are the first fully terrestrial animals.
Reptiles first appeared 350 million years ago.
3 subclasses:
 Anapsida – turtles, tortoises
 Lepidosaura – lizards, snakes, tuatara
 Archosaura – crocodiles, aligators and dinosaurs
Body plan includes:
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Thick skin with protective with surface scales to prevent water loss (gas
exchange)
Highly developed lungs with much internal folding
More developed 3 chambered heart
The amniotic egg
Lightweight skeleton
Different joint positions allowing for more efficient movement
12.4 Reptiles pg 457
12.5 Birds pg 461
Class Aves
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Characteristics of birds:
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Descendant of reptiles, similarities retained include
skull structure, and presence of scales on beak, legs
and feet.
The first endotherms
Only animal with feathers (evolved from reptilian
scales)
Their anterior limbs are modified as wings for flight,
while the posterior pair is adapted for walking,
swimming, or perching.
12.5 Birds pg 461
Class Aves
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Characteristics for Flight
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Circulatory System –4 chambered heart. No
mixing of oxygenated and deoxygenated blood.
Respiratory System – Highly developed lungs and
the presence of air sacs which provide continuous
oxygen as well as buoyancy.
Limbs – lighter, hollow bones.
Excretion – purely semi solid, no urinary bladder
Digestion – rapid and efficient
Senses – excellent hearing and acute colour
vision. Superior sight during the day and night.
12.6 Mammals pg 465
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Monotremes: mammals that reproduce by laying
eggs. Descendant of a different reptilian ancestor
than other mammals.
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Marsupials: mammals that give birth to partially
developed embryo that continue further
development in the mother’s pouch.
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Example – duck billed platypus.
Example – kangaroos, wallabies, and koalas
Placental Mammals: a type of mammal that has all
of the embryo development within the uterus of the
female. Includes 95% of all mammals.
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Example – humans, dogs, horses etc
12.6 Mammals pg 465
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Mammalian Characteristics include:
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Hair
Sweat glands
Teeth
Fleshy lips
A diaphragm
A four chambered heart
A middle ear
Mammary glands that produce milk (females)
Endoskeleton
A complex brain and nervous system
4 chambered heart
Application Questions
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Phylum Chordata
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Class Fish
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Read pgs 446-450, do questions
pg 449, questions #1, 4, pg 452
#3, 4
Read pgs 452-455, do questions
pg 454, questions #1, 5, pg 455
#4,
Class Amphibian
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Read pgs 455-457, do questions
pg 460, questions #1, 2
Application Questions
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Class Reptilia
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Class Aves
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Read pgs 457-461, do questions pg
460, questions #3, pg 461 #2,4,5
Read pgs 461-465, do questions pg
465, questions #1, 2
Class Mammalia
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Read pgs 465-478, do questions pg
478, questions #6, pg 481 # 5, 7, 9