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Kindom Animalia,
Phylum ChordataSubphylum Vertebrata
Biology 11
What characteristics set
chordates apart from other phyla?
1. Possess a notochord – (firm but flexible tube that functions in support) at least during embryionic development (but often replaced by a backbone)
2. Gill slits – at least during embryonic development-develop into gills or lungs in vertebrates
3. Dorsal nerve chord- becomes brain and spinal chord in vertebrates
4. Post anal tail
These attributes are always found in the larval forms or early embryo, although they may be absent in the adult.
**note- most possess a backbone (Tunicates and
Lancelets are an exception to this rule)
Other characteristics often
shared by vertebrates:
Endoskeleton- made of cartilage or bone and
can support a larger body
Bilateral symmetry
High degree of cephalization- well developed
head and brain protected by cranium
Closed circulatory system- heart with 2, 3, or
4 chambers
Only phylum to have bones
Tube digestive system
Vertebrate Skeletons:
Have a backbone, which surrounds the spinal
cord, is made up of bony segments called
VERTEBRAE
have an endoskeleton which has 2 main parts:
1) axial skeleton: made up of the vertebral column,
skull and rib cage
Supports body and protects the spinal column, brian & other
internal organs
2) Appendicular skeleton: made up of the
appendage bones and wide flattened girdles to which
they are attached
Is attached to the axial skeleton eg. Arms, legs.
Phylum Chordata is divided
into three subphyla Subphylum Urochordata
Example: tunuicates
Subphylum Cephalochordata
Example: Lancelets
Subphylum Vertebrata
Examples: fish, amphibians, reptiles, birds, mammals
Our focus will be on
Subphylum Vertebrata
Examples: fish, amphibians, reptiles, birds, mammals
Subphyum Vertebrata 95% of all chordates
All possess vertebrae, which are hollow cartilaginous or bony structures that surround the dorsal nerve cord.
Body plan includes: 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
Some terminology to know:
Endotherm – warm blooded animals. Internal
temperature remains constant regardless of
environment. Ex: mammals and birds.
Ectotherms – cold blooded animals. Body
temperature and metabolic rate change with
the surroundings. Ex: all other vertebrates
including fish, frogs, snakes etc.
FISH
Characteristics of ALL fish
Breathe using gills
Have 2 chambered hearts
Reproduce sexually
Fertilization & development is external in MOST
fishes
Eggs & sperm can be released directly into the
water, or deposited in more protected areas
Highly developed sensory systems
Have eyes that allow them to see objects &
contrast between light and dark in the water, but
the amount of vision varies among fishes
FISH Divided into 3
groups:
Jawless –Class
Agnatha. Ex:
lampreys, hagfish
Cartilaginous –
Class
Chondrictheys.
Ex: Sharks,
skates, rays
Bony fish - Class
Osteichthyes. Ex:
Salmon, trout,
tuna.
Organ/Structure Function
Heart 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.
Class Agnatha
Jawless fishes
No scales, eel-like body, and cartilaginous
skeleton
External fertilization
Hagfishes: feed on small invertebrates or
dead/dying fish; rough tonguelike structure
Lampreys: many are parasitic
Class Chondrichthyes
Sharks, skates, and rays
Cartilaginous fish (flexible, light-weight
skeleton)
Carnivores/scavengers
Placoid scales -small, toothlike spines
Pump water over gills by
expanding/contracting mouth cavity
Lipid-filled liver for buoyancy
Class Chondrichthyes
Convert ammonia into urea to increase
solutes in blood (no need to drink)
Internal fertilization using modified pelvic fins
(claspers)
Few lay eggs/most give have live birth
No parental care
Rays and Skates
Flattened bodies with
winglike pectoral fins
Rays-diamond or disk-
shaped bodies
Skates-triangular
Bottom dwellers
Feed on mollusks and
crustaceans
Sharks
Swim in side to side
pattern because of
asymmetrical tail fin
6-20 rows of teeth
Well-developed
olfactory bulbs
Lateral line system-
pick up electrical signals
Largest fish brain
Class Osteichthyes
Bony fishes
Early bony fishes had lungs
Swim bladder-gas filled sac controls
buoyancy (may have evolved from lungs)
Scales for protection and reduces water
resistance
Operculum is a plate that covers and
protects gills
External fertilization in most
Lobe-finned fishes
Fleshy fins
Lunfishes and coeloacanth
Use lungs and gills
Extinct lobe-finned fish are ancestors of
amphibians
Ray-finned Fishes
Fins supported by long, segmented bones
called rays
Only have gills
Reptiles
Origin & Evolution
Appeared more than 300 mya
Evolved from amphibians
1st reptiles resembled small lizards & ate
insects
Dominant land vertebrate by 250 mya
Includes fully aquatic reptiles (Ichthyosaurs)
and flying reptiles (Pterosaurs)
Dinosaurs
Mesozoic era is called “Age of Reptiles” (245-
65 mya)
Went extinct 65 mya
Asteroid-impact hypothesis: suggests an
asteroid hit Earth, dust blocked sunlight, and
climate change occurred
Sediment with iridium and quartz crystals
Crater in Yucatan dates around 65 mya
Characteristics First fully terrestrial vertebrates because
they don’t need water to reproduce
Amniotic egg: protects embryo
Scaly skin made of keratin prevents
water loss
Lungs for gas exchange
Excrete uric acid which helps retain
water
3 chambered heart (except crocodilians)
Sensory Structures
Same size brain as amphibian but more developed cerebrum for complex behavior
Strong sense of sight and hearing (except snakes)
Jacobson’s organ: in roof of mouth senses odors
Heat-sensitive pits in vipers
Turtles may pick up magnetic fields
Thermoregulation
Thermoregulation: control of body
temperature
Ectotherms: warm body by absorbing heat
from surroundings; slow metabolism (fish,
amphibians, reptiles)
Endotherms: rapid metabolism generates
heat (birds, mammals)
Reproduction
Oviparity: tough protective shell layed in
environment
Ovoviviparity: eggs retained in body until
shortly before hatching
Viviparity: no shell; live birth
Some snakes and lizard guard eggs
Crocodilians protect eggs and young for a
year or more
Order Chelonia
Turtles (aquatic) and
tortoises (terrestrial)
Carapace is top of
shell, plastron is
bottom
Vertebrae and ribs
fused to carapace
Sharp beak instead
of teeth
Order Crocodilia
Most related to
dinosaurs
Crocodiles, alligators,
caiman, and gavial
Carnivorous
Valve in back of
throat prevents water
from entering when
feeding
Order Squamata
Lizards &
snakes
Upper jaw
loosely joined to
skull
Some lizards
can detach tail
(autonomy)
Snakes
Evolved leglessness over time
Constrictors wrap around & suffocate prey
Elapids have fixed fangs (cobras, coral snakes)
Vipers have mobile fangs (rattlesnakes, copperheads, moccasins)
Birds
(Class Aves)
Evolution of Birds
The most recently evolved group of vertebrates
Evolved from small, fast-running, carnivorous dinosaurs during Jurassic Pd.
Oldest bird fossils belong to Archaeopteryx
Characteristics
Feathers
Wings
Beak (no modern bird has teeth)
Lightweight skeleton (many hollow bones)
Endothermic
Oviparity
Air sacs connected to lungs
Feathers
Modified scales that provide lift for flight and
conserve body heat
Down feathers provide insulating undercoat
Contour feathers provide coloration and
additional insulation
Flight feathers on wings and tail
Preening: birds rub feathers with oil secreted by
preen gland at base of tail
Systems
Skeletal
Fused bones
make skeleton
rigid
Large sternum
(breastbone)
supports flight
muscles
Digestion/Excretion
Crop stores food
2 part stomach:
proventriculus
and gizzard
Don’t store liquid
waste
Uric acid excreted
through cloaca
Systems
Respiratory
Oxygen stored in
air sacs
Circulatory
4 chambered
heart
Nervous
Large brains for
body size
Complex behaviors
such as navigation,
mating, nest
building
Large optic lobes
(good color vision)
Ear openings
Reproduction
Internal fertilization
Usually lay eggs in nest
1 or both parents incubate eggs with brood
patch (thickened featherless patch on
abdomen)
Precocial young are active upon hatching
(ground-nesting species)
Altricial young hatch blind, naked, and helpless
Migration
Seasonal movement dependent on temperature and food supply
Use stars, sun, landmarks, magnetic fields, changes in air pressure, and low-frequency sounds to navigate
Classification (Orders)
1. Swans, geese, & ducks
2. Owls
3. Hummingbirds & swifts
4. Parrots & relatives
5. Woodpeckers & toucans
6. Raptors (eagles, hawks, vultures)
Classification (Orders)
7. Passeriformes(songbirds);
syrinx produces songs
8. Pigeons & doves; produce crop milk for young
9. Long-legged birds (herons, storks)
10. Fowl (chicken, quail)
11. Penguins
12. Ostriches
Mammals (Class
Mammalia)
Characteristics
Endothermic
Hair
Milk produced by mammary glands
(modified sweat glands)
Specialized teeth (different
size/shape)
Lower jaw is one bone
Evolution
Major evolutionary split about 300 mya
Group 1 produced dinosaurs, birds, & modern
reptiles
Group 2 (synapsids) produced mammals
Synapsids later evolved into therapsids:
reptiles with specialized teeth,
endothermy, and legs under the body
1st true mammals (mice-like) appeared
with dinosaurs during Triassic pd
Synapsid
(Dimetrodon)Therapsid
Systems
Nervous
Large cerebrum which regulates behavior, memory, & learning
Circulatory
4 chambered heart
Respiratory
Addition of diaphragm (lg. muscle below rib cage)
Digestive
Incisors (cut food)
Canines (grip/tear)
Premolars/Molars
(crush, grind)
Many herbivores
have multi-chamber
stomach to digest
cellulose
Reproduction
Monotremes lay 1-2 eggs; young
hatch partially developed (platypus)
Marsupials: newborns do much of
their development in mother’s pouch
(kangaroo/opossum)
Placental mammals develop in the
womb
Classification (orders)
Monotremata: egg
laying (platypus)
Marsupialia:
pouches
(kangaroo)
Rodentia: rodents
Edentata:
anteaters/sloths
Lagomorpha:
rabbits
Classification
Insectivora:
hedgehogs/moles
Primates:
Monkeys/apes/hu
mans
Chiroptera: bats
Carnivora: cats,
dogs, bears, seals
Ungulates: hoofed
Classification
Cetacea:
whales/dolphin
s
Sirenia:
manatees
Proboscidea:
elephants