Download bYTEBoss 34- vertebrates revised

Chapter 34
Vertebrates
PowerPoint Lectures for
Biology, Seventh Edition
Neil Campbell and Jane Reece
Lectures by Chris Romero
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• The animals called vertebrates
– Get their name from vertebrae, the series of
bones that make up the backbone
Figure 34.1
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• There are approximately 52,000 species of
vertebrates
– Which include the largest organisms ever to
live on the Earth
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• Concept 34.1: Chordates have a notochord
and a dorsal, hollow nerve cord
• Vertebrates are a subphylum of the phylum
Chordata
• Chordates are bilaterian animals
– That belong to the clade of animals known as
Deuterostomia
• Two groups of invertebrate deuterostomes, the
urochordates and cephalochordates
– Are more closely related to vertebrates than to
invertebrates
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Mammalia
(mammals)
Reptilia
(turtles, snakes,
crocodiles, birds)
Amphibia
(frogs, salamanders)
Dipnoi
(lungfishes)
Actinistia
(coelacanths)
Actinopterygii
(ray-finned fishes)
Chordates
Craniates
Vertebrates
Gnathostomes
Osteichthyans
Lobe-fins
Tetrapods
Amniotes
Chondrichthyes
(sharks, rays, chimaeras)
Cephalaspidomorphi
(lampreys)
Myxini
(hagfishes)
Cephalochordata
(lancelets)
Urochordata
(tunicates)
Echinodermata
(sister group to chordates)
• A hypothetical phylogeny of chordates
Milk
Amniotic egg
Legs
Lobed fins
Lungs or lung derivatives
Jaws, mineralized skeleton
Vertebral column
Head
Brain
Notochord
Figure 34.2
Ancestral deuterostome
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Derived Characters of Chordates
• All chordates share a set of derived characters
– Although some species possess some of these
traits only during embryonic development
Dorsal,
hollow
nerve cord
Muscle
segments
Brain
Notochord
Mouth
Anus
Muscular,
post-anal tail
Figure 34.3
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Pharyngeal
slits or clefts
Notochord
• The notochord
– Is a longitudinal, flexible rod located between
the digestive tube and the nerve cord
– Provides skeletal support throughout most of
the length of a chordate
• In most vertebrates, a more complex, jointed
skeleton develops
– And the adult retains only remnants of the
embryonic notochord
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Dorsal, Hollow Nerve Cord
• The nerve cord of a chordate embryo
– Develops from a plate of ectoderm that rolls
into a tube dorsal to the notochord
– Develops into the central nervous system: the
brain and the spinal cord
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Pharyngeal Slits or Clefts
• In most chordates, grooves in the pharynx
called pharyngeal clefts
– Develop into slits that open to the outside of
the body
• These pharyngeal slits
– Function as suspension-feeding structures in
many invertebrate chordates
– Are modified for gas exchange in aquatic
vertebrates
– Develop into parts of the ear, head, and neck
in terrestrial vertebrates
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Muscular, Post-Anal Tail
• Chordates have a tail extending posterior to the
anus
– Although in many species it is lost during
embryonic development
• The chordate tail contains skeletal elements
and muscles
– And it provides much of the propelling force in
many aquatic species
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Tunicates
• Tunicates, subphylum Urochordata
– Belong to the deepest-branching lineage of
chordates
– Are marine suspension feeders commonly
called sea squirts
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• Tunicates most resemble chordates during
their larval stage
– Which may be as brief as a few minutes
Notochord
Dorsal, hollow
nerve cord
Tail
Excurrent
siphon
Incurrent
siphon
Muscle
segments
Intestine
Stomach
Atrium
Pharynx with slits
Figure 34.4c
(c) A tunicate larva is a free-swimming but
nonfeeding “tadpole” in which all four
chief characters of chordates are evident.
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• As an adult
– A tunicate draws in water through an incurrent
siphon, filtering food particles
Incurrent
siphon
to mouth
Excurrent
siphon
Excurrent
siphon
Atrium
Pharynx
with
numerous
slits
Tunic
Anus
Intestine
Esophagus
Stomach
Figure 34.4a, b
(a) An adult tunicate, or
sea squirt, is a sessile
animal (photo is
approximately life-sized).
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(b) In the adult, prominent
pharyngeal slits function
in suspension feeding,
but other chordate
characters are not obvious.
Lancelets
• Lancelets, subphylum Cephalochordata
– Are named for their bladelike shape
Tentacle
2 cm
Mouth
Pharyngeal slits
Atrium
Notochord
Digestive tract
Atriopore
Dorsal, hollow
nerve cord
Segmental
muscles
Anus
Tail
Figure 34.5
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• Lancelets are marine suspension feeders
– That retain the characteristics of the chordate
body plan as adults
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• Concept 34.2: Craniates are chordates that
have a head
• The origin of a head
– Opened up a completely new way of feeding
for chordates: active predation
• Craniates share some common characteristics
– A skull, brain, eyes, and other sensory organs
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Derived Characters of Craniates
• One feature unique to craniates
– Is the neural crest, a collection of cells that
appears near the dorsal margins of the closing
neural tube in an embryo
Dorsal edges
of neural plate
Neural
crest
Neural
tube
Ectoderm
Ectoderm
Notochord
(a) The neural crest consists of
bilateral bands of cells near
the margins of the embryonic
Figure 34.7a, b
folds that form the neural tube.
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Migrating neural
crest cells
(b) Neural crest cells migrate to
distant sites in the embryo.
• Neural crest cells
– Give rise to a variety of structures, including
some of the bones and cartilage of the skull
(c) The cells give rise to some
of the anatomical structures
unique to vertebrates, including
some of the bones and cartilage
of the skull.
Figure 34.7c
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Hagfishes
• The least derived craniate lineage that still
survives
– Is class Myxini, the hagfishes
Slime glands
Figure 34.9
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• Hagfishes are jawless marine craniates
– That have a cartilaginous skull and axial rod of
cartilage derived from the notochord
– That lack vertebrae
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• Concept 34.3: Vertebrates are craniates that
have a backbone
• During the Cambrian period
– A lineage of craniates evolved into vertebrates
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Derived Characters of Vertebrates
• Vertebrates have
– Vertebrae enclosing a spinal cord
– An elaborate skull
– Fin rays, in aquatic forms
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Lampreys
• Lampreys, class Cephalaspidomorphi
– Represent the oldest living lineage of
vertebrates
– Have cartilaginous segments surrounding the
notochord and arching partly over the nerve
cord
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• Lampreys are jawless vertebrates
– Inhabiting various marine and freshwater
habitats
Figure 34.10
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• Concept 34.4: Gnathostomes are vertebrates
that have jaws
• Today, jawless vertebrates
– Are far outnumbered by those with jaws
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Derived Characters of Gnathostomes
• Gnathostomes have jaws
– That evolved from skeletal supports of the
Gill slits
pharyngeal slits
Cranium
Mouth
Skeletal rods
Figure 34.13
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• Other characters common to gnathostomes
include
– Enhanced sensory systems, including the
lateral line system
– An extensively mineralized endoskeleton
– Paired appendages
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Chondrichthyans (Sharks, Rays, and Their Relatives)
• Members of class Chondrichthyes
– Have a skeleton that is composed primarily of
cartilage
• The cartilaginous skeleton
– Evolved secondarily from an ancestral
mineralized skeleton
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• The largest and most diverse subclass of
Chondrichthyes
– Includes the sharks and rays
(a) Blacktip reef shark (Carcharhinus melanopterus).
Fast swimmers with acute senses, sharks have
paired pectoral and pelvic fins.
(b) Southern stingray (Dasyatis americana).
Most rays are flattened bottom-dwellers that
crush molluscs and crustaceans for food. Some
rays cruise in open water and scoop food into
Figure 34.15a, b their gaping mouth.
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Pectoral fins
Pelvic fins
Ray-Finned Fishes and Lobe-Fins
• The vast majority of vertebrates
– Belong to a clade of gnathostomes called
Osteichthyes
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• Nearly all living osteichthyans
– Have a bony endoskeleton
• Aquatic osteichthyans
– Are the vertebrates we informally call fishes
– Control their buoyancy with an air sac known
as a swim bladder
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• Fishes breathe by drawing water over four or
five pairs of gills
– Located in chambers covered by a protective
bony flap called the operculum
Adipose fin
Dorsal fin
(characteristic of
trout)
Swim bladder
Nostril
Spinal cord
Brain
Cut edge of
operculum Gills
Heart
Figure 34.16
Gonad
Urinary
Anus bladder
Liver
Kidney
Stomach Pelvic fin
Intestine
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Caudal
fin
Anal fin
Lateral
line
Ray-Finned Fishes
• Class Actinopterygii, the ray-finned fishes
– Includes nearly all the familiar aquatic
osteichthyans
(a) Yellowfin tuna (Thunnus
albacares), a fast-swimming,
schooling fish that is an important
commercial fish worldwide
(b) Clownfish (Amphiprion
ocellaris), a mutualistic
symbiont of sea anemones
Figure 34.17a–d
(c) Sea horse (Hippocampus
ramulosus), unusual in
the animal kingdom in that
the male carries the young
during their embryonic
development
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(d) Fine-spotted moray eel
(Gymnothorax dovii), a
predator that ambushes
prey from crevices in its
coral reef habitat
• The fins, supported mainly by long, flexible
rays
– Are modified for maneuvering, defense, and
other functions
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Lobe-Fins
• The lobe-fins, class Sarcopterygii
– Have muscular and pectoral fins
– Include coelacanths, lungfishes, and tetrapods
Figure 34.18
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• Concept 34.5: Tetrapods are gnathostomes
that have limbs and feet
• One of the most significant events in vertebrate
history
– Was when the fins of some lobe-fins evolved
into the limbs and feet of tetrapods
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Derived Characters of Tetrapods
• Tetrapods have some specific adaptations
– Four limbs and feet with digits
– Ears for detecting airborne sounds
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Amphibians
• Class Amphibia
– Is represented by about 4,800 species of
organisms
• Most amphibians
– Have moist skin that complements the lungs in
gas exchange
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• Amphibian means “two lives”
– A reference to the metamorphosis of an
aquatic larva into a terrestrial adult
(b) The tadpole is
an aquatic
herbivore with
a fishlike tail and
internal gills.
(a) The male grasps the female, stimulating her to
release eggs. The eggs are laid and fertilized in
water. They have a jelly coat but lack a shell and
Figure 34.22a–c would desiccate in air.
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(c) During metamorphosis, the
gills and tail are resorbed, and
walking legs develop.
• Concept 34.6: Amniotes are tetrapods that
have a terrestrially adapted egg
• Amniotes are a group of tetrapods
– Whose living members are the reptiles,
including birds, and the mammals
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Derived Characters of Amniotes
• Amniotes are named for the major derived
character of the clade, the amniotic egg
– Which contains specialized membranes that
protect the embryo
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• Amniotes also have other terrestrial
adaptations
– Such as relatively impermeable skin and the
ability to use the rib cage to ventilate the lungs
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Reptiles
• The reptile clade includes
– The tuatara, lizards, snakes, turtles,
crocodilians, birds, and the extinct dinosaurs
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• Reptiles
– Have scales that create a waterproof barrier
– Lay shelled eggs on land
Figure 34.25
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• Most reptiles are ectothermic
– Absorbing external heat as the main source of
body heat
• Birds are endothermic
– Capable of keeping the body warm through
metabolism
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• The dinosaurs
– Diversified into a vast range of shapes and
sizes
– Included the long-necked giants called the
theropods
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Turtles
• Turtles
– Are the most distinctive group of reptiles alive
today
• Some turtles have adapted to deserts
– And others live entirely in ponds and rivers
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Birds
• Birds are archosaurs
– But almost every feature of their reptilian
anatomy has undergone modification in their
adaptation to flight
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Derived Characters of Birds
• Many of the characters of birds
– Are adaptations that facilitate flight
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• A bird’s most obvious adaptations for flight
– Are its wings and feathers
Finger 1
(b) Bone structure
Palm
(a) wing
Finger 2
Forearm
Wrist
Finger 3
Shaft
Vane
Shaft
Figure 34.28a–c
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Barb
Barbule
Hook
(c) Feather structure
• By 150 million years ago
– Feathered theropods had evolved into birds
• Archaeopteryx
– Remains the oldest bird known
Wing claw
Toothed beak
Airfoil wing with
contour feathers
Figure 34.29
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Long tail with
many vertebrae
• The demands of flight
– Have rendered the general body form of many
flying birds similar to one another
(b) Mallards. Like many bird species,
the mallard exhibits pronounced color
differences between the sexes.
(c) Laysan albatrosses. Like most birds,
Laysan albatrosses have specific
mating behaviors, such as this
courtship ritual.
(d) Barn swallows. The barn swallow is a member of
the order Passeriformes. Species in this order are
called perching birds because the toes of their feet
can lock around a branch or wire, enabling the bird
Figure 34.30b–d
to rest in place for long periods.
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• Foot structure in bird feet
– Shows considerable variation
Perching bird
(such as a
cardinal)
Grasping bird
(such as a
woodpecker)
Figure 34.31
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Raptor
(such as a
bald eagle)
Swimming bird
(such as a duck)
• Concept 34.7: Mammals are amniotes that
have hair and produce milk
• Mammals, class Mammalia
– Are represented by more than 5,000 species
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Derived Characters of Mammals
• Mammary glands, which produce milk
– Are a distinctively mammalian character
• Hair is another mammalian characteristic
• Mammals generally have a larger brain
– Than other vertebrates of equivalent size
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• The jaw was remodeled during the evolution of
mammals from nonmammalian synapsids
– And two of the bones that formerly made of the
jaw joint were incorporated into the
mammalian middle ear
Jaw joint
Key
Jaw joint
Dentary
Angular
Squamosal
Articular
Quadrate
Dimetrodon
Morganucodon
(a) The lower jaw of Dimetrodon is composed of several fused bones; two small bones, the quadrate
and articular, form part of the jaw joint. In Morganucodon, the lower jaw is reduced to a single bone,
the dentary, and the location of the jaw joint has shifted.
Middle ear
Stapes
Eardrum
Inner ear
Middle ear
Inner ear
Eardrum
Stapes
Sound
Sound
Incus (evolved
from quadrate)
Malleus (evolved
from articular)
Figure 34.32a, b
Morganucodon
Dimetrodon
(b) During the evolutionary remodeling of the mammalian skull, the quadrate and articular bones became incorporated
into the middle ear as two of the three bones that transmit sound from the eardrum to the inner ear. The steps in
this evolutionary remodeling are evident in a succession of fossils.
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Monotremes
• Monotremes
– Are a small group of egg-laying mammals
consisting of echidnas and the platypus
Figure 34.33
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Marsupials
• Marsupials
– Include opossums, kangaroos, and koalas
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• A marsupial is born very early in its
development
– And completes its embryonic development
while nursing within a maternal pouch called a
marsupium
(a) A young brushtail possum. The young of
marsupials are born very early in their
development. They finish their growth
while nursing from a nipple (in their
mother’s pouch in most species).
Figure 34.34a
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• In Australia, convergent evolution
– Has resulted in a diversity of marsupials that
resemble eutherians in other parts of the world
Marsupial mammals
Plantigale
Marsupial mole
Eutherian mammals
Deer mouse
Mole
Sugar glider
Flying squirrel
Wombat
Woodchuck
Tasmanian devil
Kangaroo
Figure 34.35
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Wolverine
Patagonian cavy
Eutherians (Placental Mammals)
• Compared to marsupials
– Eutherians have a longer period of pregnancy
• Young eutherians
– Complete their embryonic development within
a uterus, joined to the mother by the placenta
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