ClipShape of Life: Chordata

Different classes, which

includejawless fishes

(e.g., lampreys),

cartilaginous fishes (e.g.,

sharks), bony fishes,

amphibians, reptiles, birds,

and mammals.

Major CharacteristicsDorsal, hollow nerve cord-Spinal cord-Nerves branch off and

connect to organs & muscles

Notochord-Supporting rod that lies just

below the nerve cord

Pharyngeal pouches-in neck or throat regionTail that extends

beyond the anus- at some point in their

livesAnimation

Adult Derivatives of Pharyngeal Pouches

Pouch Adult derivatives

1 Lining of auditory tube and tympanic cavity (middle ear cavity)

2 Largely obliterated, lining of intratonsillar cleft (tonsilar fossa)

3 Inferior parathyroid glands, thymus

4 Superior parathyroid glands, parafollicular cells of thyroid gland

Dealing with the

environment*temperature

*salinity

Thermoregulation1.1. EctothermsEctotherms

– Obtain body heat from the environment

2.2. EndothermsEndotherms– Homeotherm– Generate own body heat- metabolism– High energy requirement– Birds and mammals able to invade colder

areas

3.3. PoikillothermPoikillotherm– Variable body temperature– Most aquatic animals (excluding sea

mammals)- body temp is same as surrounding H2O

Regulating body

temperature

Thermostat: hypothalamus

Four physical processes account for heat gain or loss

• conduction.• convection.• evaporation.• radiation.

Evaporation and convection are the most variable causes of heat loss.

Thermoregulation involves physiological and behavioral adjustments that balance heat gain and

loss:1. Adjusting rate of heat exchange between animal

and its surroundings -Alter amount of blood flowing between body core and skin

-vasoconstriction and vasodilation-altering diameter of blood vessels

-countercurrent heat exchange in extremities

2. Cooling by evaporative heat loss – panting or sweating vasoconstrictionvasodilation

3.Behavioral responses – basking in sun, migration, hibernation

4. Changing the rate of metabolic heat production – only in mammals and birds; heat produced instead of ATP (nonshivering thermogenesis); brown fat, blubber, insulation

Thermoregulation involves physiological and behavioral adjustments that balance heat gain and

loss:

Endothermy(Homeothermy)

• Only birds and mammals• Expensive

– Human – 60% of nutritional intakes goes to providing heat.

– Metabolic rate of mammals is 10x that of a reptile.

• Homotherms were able to invade colder environments.

Temperature conservation can became a problem as animals moved onto land.

Animals can maintain somewhat constant body temp by…– Snake warms itself in the sun and cools off by

hiding in the shade (Ectotherms)– Bees swarm in a hive to raise the temperature– Dogs pant– Elephants flap their ears– Humans shiver

Countercurrent Exchange• The opposite flow of adjacent fluids

that maximizes transfer rates – Heat exchange, gas exchange– Ex:

• Fish use countercurrent exchanges to maximize the extraction of oxygen from water across the membrane of their gills.

• Bird legs in water, fish tails

Water has about 10,000x less O2 than air.

Countercurrent heat exchangers

Gas exchange at the gill surface is enhanced by the opposing flows of water and blood at the gills.

Countercurrent Exchange

-blood flows opposite to the direction in whichH2O passes over gills, maintaining a constant concentration gradient for O2 between the blood and the H2O passing over the gill surface

GillsGills

Also involved in osmoregulation

Fish: Countercurrent

OsmoregulationManagement of the body’s water solute

concentration

• Marine vertebrates– ocean is hypertonic

• H2O constantly lost by osmosis

– They produce little urine & drink large amts of seawater.– Extra salt is actively transported out through the gills.

• Freshwater fish– Water is hypotonic

• H2O constantly diffuses in by osmosis

– Rarely drink– Constantly urinate– Absorb salt through gills

• Terrestrial organisms– Must rid themselves of waste but still retain

water

Osmoregulation

8 Classes

Nonvertebrate Chordates• Two groups do NOT have backbones:

1. Tunicates:-filter feeders, larval form has chordate characteristics, adults do

not2. Lancelets:

-small, fish-like, live on sandy ocean bottom Lancelet

Tunicates

lancelettunicate

•A vertebrate is an animal with a strong, flexible backbone.

•All vertebrates exhibit bilateral symmetry and a true body cavity with an endoskeleton.

•Found in aquatic and terrestrial environments.

Most Chordates are VertebratesKey Features

Endoskeleton:•Support

•Attachment for muscles•Grows with the animal

Chordata Evolution Animation

Key Features

Fishes•Aquatic vertebrates that have:

•paired fins – movement•scales – protection•gills – respiration (gas exchange)

*there are exceptions to all of these because fish are SO varied

3 classes:1. Agnatha (Gnathostomulida) -- jawless2. Chondrichthyes – cartilage skeleton3. Osteichthyes – bony fish

Major Characteristics:•Lateral Line System

•Row of sensitive cells that can detect very small amounts of motion in the water.

•Closed circulatory system•Well developed nervous system and brain•Exchange gases using gills- diffusion•Herbivores, carnivores, parasites, filter feeders, and Detritivores.•Movement- contracting muscles on either side of the backbone•Excreation-NH3 or NH4

+

2 chambered heart• One atrium and one ventricle

– Atrium- chambers that receive blood

– Ventricles-chamber that pump blood out.

• Blood flow to the tissues and back to the heart is aided by swimming motions.

• Blood travels from the heart to the gills, and then directly to the body before returning

simplest type of true heart

Temperature

• Most aquatic animals (excluding sea mammals) are poikilothermspoikilotherms.– having variable body temperature

• Maintain a body temp by seeking a region in the ocean of optimal temp and remaining there.

• Their metabolic processes do generate heat, but it is quickly dissipates into the surrounding water.

Skeleton made of fibers and cartilage

HagfishLack eyes- detect light through sensors on their

bodyFeed on dead and dying fish

Soft skin devoid of scales

•Lampreys •Usually parasitesExternal fertilization. Oviparous ( egg laying)

•Two chambered heart •Gills used for respiration

•No external ears •No eye lids

•Have funnel-like mouths lined with sharp teeth.•In center of mouth is tongue with a tooth like projection.•Attaches to other fish by suction. It tears a hole in the fish and injects a chemical that keeps the blood from clotting. Sucks blood and fluids from its host.

Vertebrate jaws evolved from skeletal supports of the pharyngeal slits

Most sharks are carnivorous

• Prey may be swallowed whole or pieces may be torn from large prey.– Teeth evolved as modified scales.– The digestive tract is proportionately shorter

than in other vertebrates.• A spiral valve, which increases surface area and

slows food movement, is present in the intestine.

•Sharks and Rays•Complete vertebral column, movable jaws, and skeleton with paired fins.

•All of these structures are made up of cartilage

•Whale shark can grow up to 49.5 ft weighing 39,600 pounds.

Clip

• Sharks have streamlined bodies and are swift swimmers.– The tail provides

propulsion.– The dorsal fins serve

as stabilizers.– Pectoral and pelvic

fins produce lift.

•Some buoyancy is provided by large amounts of oil stored in liver, but most must swim continuously to remain in the water column.•Continual swimming also produces water flow through mouth and over gills for gas exchange.

–Some sharks are known to rest on the sea floor and in caves; they use jaw and pharynx muscles to pump water over their gills while resting.

•Water enters the mouth and water passes over the gills where the gases are exchanged.•Sharp sense of smell.

•Also have lateral line lateral line systemsystem.•Internal fertilization

Internal fertilization -Ovoviviparous

• A pair of claspers on the pelvic fins of males transfers sperm into the female reproductive tract.

• Some species are oviparous, some are ovoviviparous, and a few are viviparous.

Viviparous-The embryo develops INSIDE the mother and the mother gives a live birth. Like people.Oviparous-animals that lay eggs, with little or no other embryonic development within the mother. Like chickens.Ovoviviparous-animals develop within eggs that remain within the mother's body up until they hatch or are about to hatch. Like fish.

Most abundant and diverse

Bony endoskeleton, operculum, & swim bladder

Skeleton made of boneMarine & freshwaterSwim Bladder: thin sac that acts as a float. (Filled with gasses) Can be adjusted so that the fish can move to different levels.

Salmon Migration Clip

Most-external fertilization

Lateral line system and a keen sense of smell.

No external ears

No eye lids.

1. Gills for gas exchange• gas exchange is more difficult for aquatic animals with gills than for

terrestrial animals with lungs because water is denser than air and contains less O2 per unit volume

2. Two chambered heart• only vertebrates in which blood flows directly from respiratory

organs to body tissues without first returning to the heart

• Gas exchange occurs by drawing water over the four or five pairs of gills located in chambers covered by an operculum.– Water is drawn into the

mouth, through the pharynx and out between the gills by movement of the operculum and contraction of muscles within the gill chambers.•Allows bony fishes to breath

while stationary.

mudskippersClip

Adaptations in Vertebrates for life on land

Endothermy

Strong Limbs

Muscles Eggs

Lungs

Skin

~365 mya

Amphibian Basics Clip

Major Characteristics:•Lives in water as a larvae and on land as an adult•Moist skin•Breathes with lungs as an adult•Lacks scales and claws•Must return to water to reproduce.•Age of amphibians: 360-286 mya

Clip“Double

Life”

Orders of Amphibians• Order Urodela – salamanders &

newts *long bodies and tails, 4 legs *moist/wet areas

• Order Anura – frogs and toads *all can jump *frogs more closely tied to water than toads

• Order Apoda – caecilians *least known *legless *live in water or burrow in moist soil *some have fish-like scales in their skin

Success on Land:Lungs, stronger

bones in limbs to help support weight

out of water, breastbone to

protect internal organs.

First vertebrates to adapt to life on landYoung can only live in waterUndergo metamorphosis and can live on land Tadpole stage can regenerate lost parts

Frog &Toads

•Smooth skin, no scales, feet are webbed, toes are soft and lack claws

•no external ears: have eardrums or tympanic membranes

Eggs usually Eggs usually laid in water laid in water and fertilized and fertilized

externallyexternallyAmphibian eggs lack a shell & dehydrate quickly in dry air.

In some species, males or females may house eggs on their back, in the mouth, or even in the stomach

Feeding, respiration, circulation, excretion, response, movement, reproduction

• FeedingFeeding: tadpoles are filter feeders or herbivores; frogs are carnivores*have stomach, small intestines, large intestines, cloaca

• RespirationRespiration:: *tadpoles have gills; adults have lungs and use their thin, moist skin (moist surface of mouth).

• ExcretionExcretion:: uric acid -kidneys filter wastes from blood, make urine which is stored in bladder until can be released

Circulation:Circulation: – 3 chambered heart

• 2 atria, 1 ventricle• double-loop circulation

– oxygenated and deoxygenated blood mix in the one ventricle

• Response: *well developed nervous systems, specialized sections of brain*good eyesight*hear with tympanic membrane – transmits vibrations

Feeding, respiration, circulation, excretion, response, movement, reproduction

•Movement: *tadpoles swim – tail for propulsion*adult amphibians walk or jump – legs at

sides of body

Reproduction:*use external fertilization

*Oviparous – lay eggs

*Reproductive

posture is

called

amplexus

Feeding, respiration, circulation, excretion, response, movement, reproduction

EcologyEcology•Food for

other animals

•Some can produce poison - defense

Blue Poison Frog

• Amphibians: In Cold Blood (Sir David Attenborough ) Video

Turtles, crocodilians, Lizards, and Snakes

~300 mya

In Cold Blood Clip

Major Characteristics:•Dry, scaly skin•Scales made of keratin

Helps prevent water lossWith scales or plates

Reptiles:Major Chara. Clip

Major Major Characteristics:Characteristics:•Lungs

Able to breath air

•Terrestrial eggs with several membranes (Oviparous)

Development of amniotic egg• Oviparous: animals that lay eggs

• One of the most important adaptations for life on land.• Does not need water for reproduction

internal fertilization

Development of amniotic egg: egg covered w/a shell that protects the developing embryo from drying outdrying out

Excretion: uric acid

• Some species of lizards and snakes are viviparous, their extraembryonic membranes forming a placenta that enables the embryo to obtain nutrients from its mother.

Egg Layers All turtles All tortoises All crocodilians Some lizards

Iguanas Water dragons Geckos Veiled chameleons Panther chameleons Monitors

Snakes All pythons Kingsnakes Milksnakes Rat snakes Corn snakes

Livebearers Some lizards

Solomon Island skink Blue-tongue skink     Shingle-backed skink

Some chameleons Jackson's chameleon

Some snakes All boas All vipers Garter snakes

Limbs, if present, having toes with claws used for climbing, digging, and moving around on land.

•Strong limbs

EctothermEctotherm: animals with a body temperature that is influenced by the environment

*uses behavioral adaptations to absorb solar energy and regulate its body temperature.

*Due to ectothermy, reptiles can survive on less than 10% of the calories required by mammals of comparable size.

Snakes• Jacobson's organ

• Flicking tongue helps transmit odors toward olfactory organs on roof of mouth.

• Most reptiles have a three-chambered heart; although, the ventricle is partially divided.– The partially divided ventricle

reduces mixing of oxygenated and deoxygenated blood.

Intro to Birds Clip

Strong Chests muscles

•Only group adapted to life in the air.•Body covered with feathers

•Modified scales

•Made of the protein keratin and develop in pit in the birds’ skin.

•Two types: Contour (Lift) & Down (Warmth)

•Help birds fly and keep warm•Attract mate•In some species-waterproof

Clip

The bones have a honeycombed internal structure that provides strength while reducing weight

which are that also that power that provide that ensure

have the followingadaptations to flight

Birds

Homologous tofront limbs

in othervertebrates

Providewarmth

Upward anddownward wing

strokes

One-way flowof O2-rich air

O2 distributionto body tissues

Wings Feathers Strong chestmuscles

Efficientrespiratory

system

Efficientcirculatory

system

Tutor Vista Clip: Birds

Air Flow

animation

Endotherms: A constant warm temp. generated

internally by a high metabolic rate.

 

•Birds have higher metabolic rate than mammals

•Two legs covered with scales

•Modified for specific use- perching, walking, etc.

•Front limbs modified into wings.

Molting: birds sheds their feathers at least once a year (gradual)

Thin hollow bones

-Toothless beak•Birds have many different types of feet and beaks. Modified for the life style of the bird.

Reproduction:•Internal

fertilization•Amniotic egg-

harder shells than reptiles

Digestion:Crop: Storage

Gizzard: Can contain small stones, help

with the mechanical breakdown of food

• Lungs– but have specialized air sacs and breathing

tubes that pull air in when inhale and make sure that oxygenated air is always in the lungs – air only moves in one direction, so yields high metabolic rate (provides energy, and allows birds to breath at high altitudes)

Feeding, respiration, circulation, excretion, response, movement, reproduction

The respiratory system of a bird more efficient than the human respiratory system because the bird’s respiratory system does not mix exhaled air with inhaled air- air only moves in one direction

• Response: well-developed sense organs (great senses of sight and hearing); advanced brain to interpret and respond during headlong flight

• Movement: flight, walk, run, swimming

*bones are light and filled with a scaffolding support

Feeding, respiration, circulation, excretion, response, movement, reproduction

• Circulation: four chambered heart, double loop circulation, that segregates oxygenated blood from unoxygenated blood.– The complete separation of oxygenated and

deoxygenated blood increases the efficiency of oxygen delivery to the cells.

• Excretion: nitrogen waste removed from blood by kidneys, secreted as uric acid crystals (white, pasty droppings, little water)

–uric acid =Allows water conservation

Feeding, respiration, circulation, excretion, response, movement, reproduction

Birds also have a very well developed nervous system.• Acute vision and well-developed visual and coordinating areas of the brainaid in flying.• They show complex behavior especially during breeding season whenelaborate courtship rituals are performed.

• Reproduction: separate sexes, internal fertilization, amniotic eggs

*some parent birds can produce and regurgitate a substance from the crop that is rich in protein and fat to feed offspring – “bird milk”; this is actually just sloughed-off cells from their crop mixed with saliva and mucus

Feeding, respiration, circulation, excretion, response, movement, reproduction

Esophagus

Crop

Liver

GizzardSmallintestine

Cloaca

Pancreas

Air sacKidney

HeartLung

BrainWhen a bird eats,food moves downthe esophagus andis stored in the crop.

1

As digestion continues,the food moves throughthe intestines.

4 Undigested food isexcreted through thecloaca.

5

Large intestine

The muscular wallsof the gizzard squeezethe contents, while small stones grind the food.

3

Moistened food passes to the stomach, a two-part chamber. The first chamber secretes acid and enzymes. The partially digested food moves to the second chamber, the gizzard.

The Anatomy of a Pigeon

2

First chamber of stomach

There are many species of flightless birds: ostrich, penguins

Emus

Rheas

Cassowary

EcologyPollination

Seed dispersalControl insect populationsIndicator of environmental

healthRachel Carson‘s book Silent Spring - pesticides in the food

chain

Humans, Manatees, Elephants, Kangaroos, Apes, Tigers, Dogs

Major Characteristics•Body covered with hair made of keratin-provides insulation•Young nourished in the uterus •Young nourished w/milk from mammary glands•lung-breathing throughout lifetime•Differentiated teeth•Large brains-capable of learning

Intro to mammals Clip

Major Characteristics•Endothermic

•Subcutaneous fat under skin to conserve heat

•Sweat glands to cool body

Feeding:•Carnivores, herbivores, and

omnivores.•Evolution of a strong more

powerful jaw enabled mammals to eat food other

than insects.

Reproduction:•Internal fertilization

Placental Placental ((Eutherian) mammalsmammals: Live birthMonotremesMonotremes:Egg-laying mammals: platypuses and echidnas -After hatching, young suck milk from the fur of the mother who lacks nipples.

MarsupialsMarsupials:Pouched mammals: Kangaroo, koalas, opossum

**Young are born in an early stage of development and completes its development while nursing.

Australian monotremes and marsupials: echidna (top left), marsupial mouse (lower left), sugar glider (right)

Monotremes:Egg-laying mammals

• Excretion-Urea– less toxic than NH3 and requires less

H2O

– NH3 converted to urea in liver

• Kidneys filter blood, add water to make urine.

Form and Function of Mammals• Jaws and teeth allow for diverse diet• Highly developed brains with good

senses – taste, sight (color vision), smell, hearing (ears with chambers), touch

• Movement varied: run, walk, climb, burrow, hop, pounce, swing, fly, leap, and swim

Circulation

• Double-loop circulation, 4 chambered heart

• two atria and two ventricles• deoxygenated and oxygenated

bloods are not mixed

Pig