Download Echinodermata

The Animal Kingdom:
The Deuterostomes
Chapter 31
Learning Objective 1
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What are the shared derived characters of
deuterostomes?
Deuterostomes 1
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Include echinoderms, hemichordates,
chordates
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Hemichordates (acorn worms)
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marine deuterostomes
three-part body (proboscis, collar, trunk)
Deuterostomes 2
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Shared derived characters
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radial, indeterminate cleavage
blastopore becomes anus
larva have a loop-shaped ciliated band used
for locomotion
KEY CONCEPTS
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The echinoderms and the chordates are
the two most successful deuterostome
lineages in terms of diversity, number of
species, and number of individuals
Learning Objective 2
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What are three shared derived characters
of echinoderms?
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Describe the main classes of echinoderms
Phylum Echinodermata
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Marine animals with
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spiny “skin”
water vascular system
tube feet
endoskeleton
Larvae exhibit bilateral symmetry
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Most adults exhibit pentaradial symmetry
Sea Star Body Plan
Stomach
Digestive
gland
Anus
Ampulla
Tube feet
Spine
Gonad
Dermal gill
Pedicellariae
Fig. 31-2a, p. 670
Class Crinoidea
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Sea lilies, feather stars
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oral surface turned upward
some crinoids are sessile
Class Asteroidea
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Sea stars
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central disc with five or more arms
use tube feet for locomotion
Class Ophiuroidea
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Brittle stars
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arms longer, more slender than sea stars
arms more distinct from central disc
use arms for locomotion
tube feet lack suckers
Class Echinoidea
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Sea urchins, sand dollars
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lack arms
have a solid shell
are covered with spines
Class Holothuroidea
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Sea cucumbers
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elongated flexible bodies
circle of modified tube feet surrounds mouth
Fig. 31-1, p. 669
KEY CONCEPTS
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Echinoderms are characterized by radial
symmetry in adults, a water vascular
system, tube feet, and spiny skin
Learning Objective 3
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What are five shared derived characters of
chordates?
Phylum Chordata 1
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Subphylum Urochordata
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Subphylum Cephalochordata
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Subphylum Vertebrata
Chordate Evolution
Phylum Chordata 2
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At some time during life cycle have
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flexible, supporting notochord
dorsal, tubular nerve cord
pharyngeal (gill) slits
muscular postanal tail
endostyle (or thyroid gland)
Chordate Body Plan
Brain
Dorsal, tubular
nerve cord
Notochord
Mouth
Pharynx
Postanal
tail
Anus
Pharyngeal
(gill) slits
Intestine
Muscular
segments
Heart
Fig. 31-4, p. 671
KEY CONCEPTS
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At some time in its life, a chordate has a
notochord; dorsal, tubular nerve cord;
pharyngeal slits; and a muscular postanal
tail
Learning Objective 4
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What are the invertebrate chordate
subphyla?
Subphylum Urochordata
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Tunicates
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marine animals with tunics
suspension-feeders
Larvae are free swimming
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Most adults are sessile
Tunicate Body Plan
Vertebrata
Cephalochordata
(lancelets)
Urochordata
(tunicates)
Hemichordata
(acorn worms)
Echinodermata (sea
stars, sea urchins)
Chordata
Deuterostome
ancestor
Fig. 31-5a, p. 672
Incurrent siphon
Ganglion
Oral tentacles
Pharynx with
slits
Excurrent
siphon
Atrium
Endostyle
Tunic
Intestine
Esophagus
Testis
Digestive
gland
Ovary
Heart
Stomach
Fig. 31-5b, p. 672
0.5 mm
Fig. 31-5c, p. 672
Pharynx
with
slits
Incurrent
opening
Atrium
Excurrent
opening
Nerve cord
Adhesive
papilla
Notochord
Heart
Stomach
Fig. 31-5d, p. 672
Subphylum Cephalochordata
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Lancelets
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small, segmented, fishlike animals
Vertebrata
Cephalochordata
(lancelets)
Urochordata
(tunicates)
Hemichordata
(acorn
worms)
Echinodermata
(sea stars, sea
urchins)
Chordata
Deuterostome
ancestor
Fig. 31-6 (1), p. 673
Tentacles
Nerve
cord
Notochord
Pharyngeal
slits
Intestine
Caudal
fin
Tentacles
Endostyle
Atrium
Gonads Atriopore
Anus
Fig. 31-6 (a-b), p. 673
Learn more about the body plans
of the deuterostomes by clicking
on the figures in ThomsonNOW.
Learning Objective 5
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Discuss the evolution of chordates
Evolution of Chordates
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Urochordates (tunicates)
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probably first chordates to evolve
Subphyla Cephalochordata and Vertebrata
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sister taxa (recent common ancestor)
Vertebrate Evolution
Explore the evolutionary
relationships of vertebrates by
clicking on the figure in
ThomsonNOW.
Learning Objective 6
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What are four shared derived characters
of vertebrates?
Vertebrates 1
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Vertebral column
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Cranium
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chief skeletal axis of body
braincase
Neural crest cells
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determine development of many structures
Vertebrates 2
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Pronounced cephalization
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Complex brain
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Muscles attached to endoskeleton for
movement
KEY CONCEPTS
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Shared derived characters of vertebrates
include a vertebral column, cranium,
neural crest cells, and an endoskeleton of
cartilage or bone
Learning Objective 7
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What is the difference between the major
groups of jawless fishes?
Jawless Fishes 1
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Ostracoderms (extinct)
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Agnathans (hagfishes)
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among earliest known vertebrates
class Myxini
Lampreys
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class Cephalaspidomorphi
Hagfish
Lampreys
Hagfishes
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Have no trace of vertebrae
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Why are they classified as vertebrates?
Some systematists classify vertebrates
plus hagfishes as craniates (Craniata)
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But molecular data support classifying
hagfishes as vertebrates
Jawless Fishes 2
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Jaws and paired fins absent
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Hagfishes
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in both hagfishes and lampreys
marine scavengers
secrete slime as a defense mechanism
Lampreys
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many are parasites on other fishes
Learning Objective 8
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Trace the evolution of jawed fishes and
early tetrapods
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Identify major taxa of jawed fishes and
amphibians
Class Chondrichthyes
(Cartilaginous Fishes)
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Includes sharks, rays, skates
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Cartilaginous fishes have
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jaws
two pairs of fins
placoid scales
Cartilaginous
Fishes
Shark Structure
Spleen Kidney
Stomach Testis
Gill slits
Clasper
Mouth
Pelvic Cloaca Intestine Pancreas
fin
Liver
Heart Pericardial Pharynx
cavity
Internal structure of a shark.
Fig. 31-12a, p. 679
Spleen
Kidney
Stomach Testis Gill slits
Clasper
Mouth
Pelvic Cloaca Intestine Pancreas
fin
Liver
Heart Pericardial Pharynx
cavity
Internal structure of a shark.
Stepped Art
Fig. 31-12a, p. 679
Enamel
Pulp cavity
Dentine
Epidermis
Dermis
Structure of a placoid scale.
Fig. 31-12b, p. 679
Shark Reproduction
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Oviparous
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Ovoviparous
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lay eggs
young enclosed by eggs
incubated in mother’s body
Viviparous
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young develop in mother’s uterus
nutrients transferred from mother’s blood
Bony Fishes
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Class Actinopterygii
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Class Actinistia
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ray-finned fishes
coelacanths
Class Dipnoi
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lungfishes
Bony Fishes
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During the Devonian, bony fishes gave
rise to two evolutionary lines:
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Actinopterygii (ray-finned fishes)
Sarcopterygii (lobe-finned fishes)
Early Jawed Fishes
Ray-Finned Fishes
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Gave rise to modern bony fishes
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Lungs modified as swim bladder
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air sac for regulating buoyancy
Modern Bony Fishes
Bony Fish Structure
Swim bladder Nerve cord
Dorsal fins
Kidney
Ureter
Caudal fin
Brain
Nostril
Pharynx
Gills
Heart
Urinary
bladder
Anal fin
Gonad
Liver
Cloaca
Stomach Pelvic fin Intestine
Fig. 31-13, p. 680
KEY CONCEPTS
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Jaws and fins were key adaptations that
contributed to the success of jawed fishes
Sarcopterygii
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Gave rise to
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lungfishes (class Dipnoi)
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coelacanths (class Actinistia)
Sarcopterygii
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Lungfishes gave rise to tetrapods
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land vertebrates
Tiktaalik
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transitional between fishes and tetrapods
Early Tetrapods
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Early amphibians
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mainly aquatic
moved onto land to find food, escape
predators
had limbs strong enough to support body
weight on land
Class Amphibia 1
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Salamanders, frogs and toads, caecilians
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Most return to water to reproduce
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Frogs
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embryos develop into tadpoles, which
undergo metamorphosis to become adults
Insert “Salamander
locomotion”
salamander_walk.swf
Modern
Amphibians
Class Amphibia 2
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Use moist skin as well as lungs for gas
exchange
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Have a three-chambered heart
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systemic and pulmonary circulations
Learn more about jawless, early
jawed, cartilaginous, and bony
fishes by clicking on the figures
in ThomsonNOW.
Learning Objective 9
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What are three vertebrate adaptations to
terrestrial life?
Terrestrial Vertebrates
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Amniotes
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Amniotic egg (with shell and amnion)
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include reptiles, birds, mammals
important adaptation for life on land
Amnion (membrane)
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forms fluid-filled sac around embryo
Amniotic Egg
Amnion (protects embryo)
Embryo
Chorion
(encloses entire embryo)
Allantois
(stores wastes in
reptiles and birds)
Yolk sac
(encloses yolk,
provides nutrients)
Shell
Albumen (provides nutrients)
Fig. 31-19, p. 683
Amniotes
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Have body covering that retards water loss
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Have physiological mechanisms that
conserve water
Learn more about the amniotic
egg by clicking on the figure in
ThomsonNOW.
Learning Objective 10
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Describe reptiles and birds
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Give an argument for including birds in the
reptile clade
Class Reptilia
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A paraphyletic group
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dinosaurs, turtles, lizards, snakes, alligators
Biologists classify amniotes in two main
groups: diapsids and synapsids
Amniotes
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Diapsids
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turtles, ichthyosaurs, tuataras, squamates
(snakes and lizards), crocodiles, pterosaurs,
saurischian dinosaurs, birds
Synapsids
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gave rise to therapsids, which gave rise to
mammals
Diapsids
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Many biologists consider birds
as feathered dinosaurs
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classify birds and most
reptiles as diapsids
Pelvis
Leg
Feathers
Fig. 31-22b, p. 688
Therapsid
Amniote Evolution
4 Groups of Extant Reptiles
1. Turtles, terrapins, tortoises
4 Groups of Extant Reptiles
2. Lizards, snakes, amphisbaenians
4 Groups of Extant Reptiles
3. Tuataras
4 Groups of Extant Reptiles
4. Crocodiles, alligators, caimans, gavials
Reptile Characteristics 1
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Reproduction
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internal fertilization
leathery protective shell around egg
embryo develops protective membranes
(including amnion)
Reptile Characteristics 2
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Dry skin with horny scales
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Lungs with many chambers
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Three-chambered heart
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some separation of oxygen-rich and oxygenpoor blood
Birds 1
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Adaptations for powered flight
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feathers
wings
light, hollow bones containing air spaces
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Four-chambered heart
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Very efficient lungs
Birds 2
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Excrete solid metabolic wastes (uric acid)
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Endotherms
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maintain constant body temperature
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Well-developed nervous system
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Excellent vision and hearing
Modern Birds
KEY CONCEPTS
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Limbs, a body covering that retards water
loss, and the amniotic egg, with its shell
and amnion, were key adaptations that
contributed to the success of terrestrial
vertebrates
Learning Objective 11
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Contrast monotremes, marsupials, and
placental mammals
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Give examples of animals that belong to
each group
Mammals
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Characterized by
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hair
mammary glands
differentiated teeth
three middle-ear bones
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Have highly developed nervous system
and muscular diaphragm
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Are endotherms
Monotremes (Subclass Holotheria)
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Duck-billed platypus, spiny anteaters
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Monotremes lay eggs
Marsupials (Subclass Metatheria)
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Include pouched mammals
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kangaroos, opossums
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Young are born in embryonic stage
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Complete development in mother’s
marsupium
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nourished with milk from mammary glands
Marsupials
Placental Mammals
(Subclass Eutheria)
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Characterized by placenta
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for exchange between embryo and mother
Mammal Evolution