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