Transcript Chapter 26

Chapter 26
Vertebrates
A Summary
AP Biology
Spring 2011
Chordates
 Vertebrates include:
 Fish
 Amphibians
 Reptiles
 Birds
 Mammals
 Are coelomate,
bilateral animals
Chordates
 Many of 4 anatomical features that characterize chordates
appear only during embryonic development
 Notochord: 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
Vertebrates
 Have an internal skeleton and big brain
 Internal skeleton: enlcoses and protects internal organs and
works with muscles to produce movement
 Have several advantages of external skeletons:
 Cells are living so skeleton foes not have to be molted
 Allows for greater flexibility
 Is lightweight
Vertebrates
 Notochord 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
Vertebrates
 Circulatory 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
Vertebrates
 Other organ systems
 Have paired kidneys to deal with internal fluid composition
 Reproduce sexually
 Have well developed immune system
Gnathostomes
 Vertebrates that have jaws
 Jaws of vertebrates evolved from modification of skeletal
parts that had once supported the pharyngeal (gill) slits
Gnathostomes
 Class Chondrichthyes: sharks and rays
 Have flexible endoskeletons composed of cartilage, possess
streamlined bodies, are denser than water, will sink if stop
swimming
Gnathostomes
 Class Osteichthyes: bony fish
 Most numerous of vertebrate groups
 Two main classes of bony fish are ray finned and lobed fins
 Have an ossified endoskeleton, covered in scales, posses a swim
bladder
Pisces
 Fish
 Are cold blooded vertebrates that have:
 Gills
 Scales
 Two chambered heart
Gnathostomes
 Tetrapods that have four limbs and feet
 Class amphibia
 Not all have legs
 Frogs
Amphibia
 Cold-blooded
 Initially breath through gills
 Then develop lungs
 Can also exchange gas through their moist skin
 Have a three chambered heart
 Close ties with water
 Their eggs lack a shell
 Fertilization is external
 Can exhibit complex social behaviour
Amniotes
 Tetrapods that have a terrestrially adapted egg
 Consist 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
Reptilia
 Cold-blooded
 Have eggs with a chitinous covering
 Lay eggs on land
 Undergo internal fertilization
 Have a four chambered heart
 First vertebrates to have internal fertilization
 Have scales containing keratin
 Adaptation for terrestrial living
 Obtain oxygen through their lungs, not skin
Reptilia
 Extinct reptiles:
 Dinosaurs (lived on land)
 Pterosaurs (flying reptiles)
 Plesiosaurs (marine reptiles)
 Modern reptiles:
 Turtles, tuataras, lizards, snakes, alligators, crocodiles
 Most are ectothermic
 Regulate body temperature through behavioral adaptations
rather than by metabolism
Aves
 Birds
 Warm-blooded
 Have eggs with shells
 Lay amniotic eggs
 Wings, feathers, hollow bones
 Four-chambered heart
 High rate of metabolism
 Have keratin containing scales on their legs
 Scales and eggs are reptilian characteristics
Aves
 Most birds bodies are constructed for flight:
 Light, hollow bones
 Relatively few organs
 Wings
 Feathers
 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
Mammalia
 Warm-blooded (endotherms)
 Active metabolism
 Most are born rather than hatched
 Use internal fertilization
 Large brains
 Four-chambered heart
 Have hair and produce milk to feed their young
 All have teeth of differing size and shape
Mammalia
 Some 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
Mammalia
 Marsupials 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)
Mammalia
 Monotremes: egg laying mammals
 Duck billed platypus and spiny anteater
 Derive nutrients from shelled egg
Mammalia: Primates
 Humans are primates
 Primates 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: Primates
 Eyes 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: Primates
 Devote 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: Primates
 Include:
 Humans
 Gorillas
 Chimpanzees
 Orangutans
 Gibbons
 Old world and new world monkeys