Chapter 26
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Transcript of Chapter 26
VertebratesA Summary
Chapter 26
AP Biology Spring 2011
ChordatesVertebrates include:
FishAmphibiansReptilesBirdsMammals
Are coelomate, bilateral animals
Chordates Many of 4 anatomical features that
characterize chordates appear only during embryonic developmentNotochord: long, flexible rod that appears during
embryonic development between the digestive tube and the dorsal nerve cord
Dorsal, hollow nerve cord: formed from a plate of ectoderm that rolls into a hollow tube
Pharyngeal clefts: grooves that separate a series of pouches along the sides of the pharynx; in most chordates the clefts develop into slits that allow water to enter and exit he mouth without going through the digestive tract
A muscular tail posterior to the anus
VertebratesHave an internal skeleton and big brainInternal skeleton: enlcoses and protects
internal organs and works with muscles to produce movementHave several advantages of external
skeletons:Cells are living so skeleton foes not have to be
molted Allows for greater flexibility Is lightweight
VertebratesNotochord develops into
vertebral column which encloses and protects spinal cord
Have large brains with paired eyes and ears
With the exception of lampreys, have jaws
VertebratesCirculatory and respiratory system
Paired gills evolved in early vertebrates and allowed for faster, more efficient gas exchange
Before transition to land, several species of fish developed small outpouchings in the side of the gut that evolved into lungs
Have a closed circulatory system which makes circulation faster
Gradually, there was less reliance on gills and more on lungs and circulatory system (heart, blood vessels), which work in connection
VertebratesOther organ systems
Have paired kidneys to deal with internal fluid composition
Reproduce sexually Have well developed immune system
GnathostomesVertebrates that have jaws Jaws of vertebrates evolved from
modification of skeletal parts that had once supported the pharyngeal (gill) slits
GnathostomesClass Chondrichthyes: sharks and rays
Have flexible endoskeletons composed of cartilage, possess streamlined bodies, are denser than water, will sink if stop swimming
GnathostomesClass Osteichthyes: bony fish
Most numerous of vertebrate groupsTwo main classes of bony fish are ray finned
and lobed finsHave an ossified endoskeleton, covered in
scales, posses a swim bladder
PiscesFishAre cold blooded vertebrates that have:
GillsScalesTwo chambered heart
GnathostomesTetrapods that have four limbs and feetClass amphibia
Not all have legs Frogs
AmphibiaCold-bloodedInitially breath through gillsThen develop lungsCan also exchange gas through their moist
skin Have a three chambered heart Close ties with waterTheir eggs lack a shellFertilization is externalCan exhibit complex social behaviour
Amniotes Tetrapods that have a terrestrially adapted
eggConsist of mammals and reptiles and birds Amniotic egg
Important evolutionary development for life on land
Have shell that retains water and can be laid in a dry environment
Have extraembryonic membranes that function in gas exchange, waste storage and transport of nutrients to embryo
ReptiliaCold-bloodedHave eggs with a chitinous covering
Lay eggs on landUndergo internal fertilization
Have a four chambered heartFirst vertebrates to have internal fertilizationHave scales containing keratin
Adaptation for terrestrial living Obtain oxygen through their lungs, not skin
ReptiliaExtinct reptiles:
Dinosaurs (lived on land)Pterosaurs (flying reptiles)Plesiosaurs (marine reptiles)
Modern reptiles:Turtles, tuataras, lizards, snakes, alligators,
crocodilesMost are ectothermic
Regulate body temperature through behavioral adaptations rather than by metabolism
AvesBirdsWarm-bloodedHave eggs with shells
Lay amniotic eggsWings, feathers, hollow bonesFour-chambered heart
High rate of metabolism Have keratin containing scales on their legsScales and eggs are reptilian
characteristics
AvesMost birds bodies are constructed for flight:
Light, hollow bonesRelatively few organsWingsFeathers
Endotherms: maintain warm, consistent body temperature
Feathers and in some cases a layer of fat insulate birds and help maintain internal temperature
Have larger brains than amphibians and nonbird reptiles do
MammaliaWarm-blooded (endotherms)Active metabolism Most are born rather than hatched Use internal fertilization Large brainsFour-chambered heart Have hair and produce milk to feed their
young All have teeth of differing size and shape
MammaliaSome have a placenta (eutherians)
Structure that nourishes fetus Embryo develops internally in a uterus
connected to mother by placenta, where nutrients diffuse from mother to embryo
MammaliaMarsupials do not have a placenta
Developing embryo receives little nourishment from mother in the uterus
About eight days after fertilization, fetus must continue its maturation in mother’s pouch (nurses)
MammaliaMonotremes: egg laying mammals
Duck billed platypus and spiny anteater Derive nutrients from shelled egg
Mammalia: PrimatesHumans are primatesPrimates descended from insectivores,
probably from small, tree dwelling mammals
Have dexterous hands and opposable thumbs Make it possible to do fine motor tasks
Nails have replaced claws Hands and fingers contain many nerve
endings and are sensitive
Mammalia: PrimatesEyes are front facing and set close together
Front facing eyes fosters face-to-face communication
Close set eyes are responsible for overlapping fields of vision, which enhances depth perception and hand-eye cordination
Mammalia: PrimatesDevote much energy to parenting of young
Engage in most intense parenting of any mammal
Usually have single births and nurture young for long time period
Mammalia: PrimatesInclude:
HumansGorillasChimpanzeesOrangutansGibbons Old world and new world monkeys