Transcript I Unit 9 PPT

Mammals
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Mammals
Kingdom Animalia
---Phylum Chordata
-----Subphylum Vertebrata
---------Class Mammalia
What do you get when
you cross an elephant
with a fish?
swimming trunks
Evolution and Characteristics
Mammals belong to
the class
Mammalia, which
includes 4000
species
Most dominant
land animals on
earth.
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Origin
Fossil skeletons show that
early mammals had large
eye sockets, which may
have meant that they
were active at night.
Mammals did not compete
with dinosaurs for food,
and fed primarily on
insects.
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Origin
Mammals were not
abundant during the
Mesozoic era.
Fossils of the first
mammals are scarce,
thus indicating that they
were not as abundant.
The Cenozoic era is called
the Age of Mammals,
for this is when they
proliferated rapidly.
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Origin
Thus, mammals did not come to
dominate until after the dinosaurs
became extinct
Early
mammals were
probably
rodent-like
and nocturnal
Evolution
•Animals evolved from
the group of reptiles
called Therapsids.
•Therapsids have both
reptilian and
mammalian
characteristics.
•Therapsids have a jaw
bone composed of 5
bones rather than a
simple jaw bone.
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Evolution
•Like
mammals, Therapsids have
specialized teeth adapted for
specialized functions.
•The earliest mammalian fossil found is
from the early Mesozoic era, 200
million years ago
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Mammal Characteristics
• Endothermic
• Have hair
• Well-developed
brains
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How do mammals stay warm?
Hair insulates most mammals
Some marine mammals have a layer of
subcutaneous fat (blubber)
Mammal Characteristics
• Mammalian
heart has 4
chambers
• Mammals have
a muscle , the
diaphragm,
that aids in
breathing
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How the Diaphragm Works
Mammal Characteristics
• Mammals have a single lower jaw
• Most species have 4 different
types of teeth
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Specialized Teeth
• incisors – biting
• canines - stabbing, holding
• molars - crushing, grinding
Different types of mammals have
different types of teeth
- depends on their diet
Predators have large canines
Herbivores have large flat molars
The canines of
predators are very
large and sharp,
used for tearing
flesh
Mammal Characteristics
• Most species are viviparous, in which
females carry their young until full
development
• Females secrete milk from mammary
glands to feed newborn young.
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What are mammary glands?
Only found in mammals, produce
milk to feed young.
Mammal Characteristics
Two features that distinguish them from
other invertebrates are: 1) all have
hair; 2) all produce milk.
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Body Plan
• Range in size from 1.5 g to
130 tons
• Endoskeleton
• Striated and smooth muscles
• 4 limbs
• 2 sets of teeth—permanent
and milk
• Moveable eyelids
SKIN
• Integument with glands
– Sweat
– Sebaceous (oil)
– Mammary
– Scent
• Exposed areas of skin covered with
thick cornified layers of keratin
• Thicker then most animals
– Dermis and epidermis
SKIN
• Skin covered with hair ( may
be reduced in some)
– Protects, camouflage, keeps
dry
– May molt (shed) periodically
– May be modified into spines
or whiskers
Keratinized Epidermis of antlers/hornes
HORNES
– True horns found in
ruminants
(sheep/cattle)
– Hollow sheaths
– Bone at the core
arising from skull
– Not shed
– Not branched
– May curve
– May be absent in
females
ANTLERS
– Possessed by deer family
– Composed of solid bone
– Shed annually after
breeding season
– Annual spring regrowth—
velvet
– Branched
– Only males produce
antlers (except caribou)
Rhino Horns
• Not really horns
– Hair-like keratinized
filaments that are cemented
together
• Pushing the Asian and African
rhinos toward extinction
– Aphrodisiac, treating heart
and liver disease
– To make daggers
Antler design
Blood supply
while in velvet
Respiration
• Lungs with alveoli
• Voice box and larynx
• Epiglottis to separate
esophagus from
trachea
• Diaphragm
–Positive pressure
Circulation
• Closed circulatory
system
• Pulmonary system
• 4 chambered heart
• Non-nucleated red
blood cells
Nutrition
• Some mammals require a specialized diet,
others depend on a diverse diet
–
–
–
–
Carnivores
Insectivores
Herbivores
Omnivores
• Teeth typically dictate what a mammal
eats
– Cut, gnawing, tearing grinding and chewing
• The smaller the animal, the greater its
metabolic rate  amount of food needed
is increased
Nutrition – The Caecum
Cellulose Digestion
• The caecum is also responsible for
breaking down the cellulose fibers
from digesting plant matter. Animals,
both herbivores and omnivores, take in
cellulose when eating plants. Bacteria
and enzymes in the caecum of these
animals cause fermentation that
breaks down cellulose fibers, which
then allows the rest of the large
intestine to digest the nutrients from
cellulose.
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D
I
G
E
S
T
I
O
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Excretion
• Complex kidney with
tubules
– Ureters open to a
bladder
• Secretion of uric acid
– Helps conserve water
Nervous System
• Highly developed brain
• Two hemispheres of cerebrum
• Occipital lobe
• cerebellum
• 12 pairs of cranial
nerves
• Highly evolved senses
Reproduction
•
•
•
•
Dioecious
Sexual/internal fertilization
Oviparous
Viviparous
– Marsupials finish embryonic development in
pouch
– Placental animals have a long gestation within
the uterus
• Some mammals can retain a
fertilized egg in uterus until
favorable conditions exist for birth
Reproduction
• Number of young/season
(fecundity) depends on mortality
rate
– Usually the larger the animal,
the smaller the number of
young in a litter
• Young are nourished by mammary
glands secreting milk
• Mammals claim territory,
especially during mating season
Development
• Length of development depends
upon species type
– Some animals are born deaf
and blind
– Others must defend themselves
within minutes
• All exhibit some sort of youth,
defended and taught by adults
• Life spans also vary widely
Mammal Orders
There are 19 orders of mammals in
the class Mammalia in which 17
nourish unborn young via a
placenta. The others are egg
laying mammals and marsupials.
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What is the placenta?
Attached to the
wall of the uterus ,
it provides the
fetus with
nourishment.
Monotremes and Marsupials
Only 5 percent of all mammalian species
are in the orders Monotremata and
Marsupialia.
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Monotremata
• Oviparous or egg laying mammals
• Only 3 in existence – all in Australia
• Duck-billed platypus and two species of spiny
anteaters called echidna.
• Not completely endothermic (their body
temperature is lower and fluctuates more
than other mammals)
• Have reptilian characteristics (cloaca & egg
laying)
• Have mammalian features (hair, mammary
gland)
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Duck Billed Platypus
and the Echidna
(also called Spiny Anteater)
Marsupials
• Marsupials give birth to tiny
immature young that crawl to a
pouch on the mothers belly
immediately after they are
born.
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Kangaroo Birth
They attach
themselves to
milk secreting
nipples, nursing
until they are
mature enough
to survive
outside the
pouch.
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250 species of marsupial species
exist in Australia, New Guinea,
• .
Tasmania, And the Americas
Tasmanian
Devil
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Marsupial Examples
Can you
name
these
animals?
The only American marsupial
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Adaptive Radiation
• 60 hundred million years ago, no
placental mammals inhabited the
continent
• Lacking in competition Australian
marsupials underwent adaptive radiation:
The evolutionary diversification of a
species or single ancestral lineage into
various forms that are each adaptively
specialized to a specific environmental
niche. Adaptive radiation generally
proceeds most rapidly in environments
where there are numerous unoccupied
niches or where competition for
resources is minimal.
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Placental Mammals
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Characteristics of Placentals
• Placental mammals carry unborn young in the
uterus until they can survive in the wild.
• Oxygen and nutrients are transferred from
mother’s blood to baby’s blood via the
placenta
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Placental Characteristics
• The placenta is a
membrane providing
nutrient, waste, and
gas exchange between
the mother and
developing young
• Gestation period - the
time in which mammals
fully develop in the
mother’s uterus
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Mammals are a diverse group, living
on land and in water. Some mammals
can fly!
Walrus
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Insectivora
• Consists of 400 species
• Includes shrews and moles
Shrew
Mole
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Insectivora
• Small animals with high metabolic
rate, found in North America,
Europe, and Asia.
• Most have long pointed noses that
enable them to grub for insects,
worms, and invertebrates.
• Live on ground, trees, in water,
and underground.
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Rodentia
• Largest mammalian order having over
2,400 species.
• On every continent except for
Antarctica
• Includes squirrels, marmots, chipmunks,
gophers, muskrats, mice, rats, and
porcupines.
Chipmunk
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Marmot
Porcupine
Squirrel
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Only two incisors in each
jaw, grow as long as
rodent lives, and used for
gnawing
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Lagomorpha
• Includes rabbits, hares, and small
mountain mammals called pikas.
• Found worldwide
Hare
Pika
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Lagomorpha
Double row of incisors, large front
teeth backed with two smaller
ones, adaptation for herbivorous
diet.
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Edentata
• Made up of 30 living species including
anteaters, armadillos, and sloths.
• The name edentate means “without
teeth”
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Anteater
Sloths
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Armadillo
Edentates have adaptations for
insectivorous diets, including a
long, sticky tongue and clawed
front paws
Anteater feeding at
a Termite mound
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Sloths, on the other hand, have
continuously growing teeth as an
adaptation for grinding plants
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Chiroptera
• Made up of over 900 species of bats
• Live throughout the world except in polar
environments
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• A bat’s wing is a modified front limb,
with membranous skin between
extremely long finger bones
• Bats use thumbs for climbing, walking,
or grasping
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• Most bats are active at night and have
a special way to navigate using
echolocation (bounce-back of highfrequency sound waves)
• Frequency of returning sound waves
depicts the size, distance, and rate of
movement of different objects
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Chiroptera
• Bats that use
echolocation have
small eyes and
large ears.
• Feed on insects
and have teeth
specialized for
such diets
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• Some bats feed on fruit and flower
nectar and do not use echolocation.
• These large bats are sometimes
called flying foxes, have large eyes,
and a keen sense of smell.
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Cetacea and Sirenia
• 90 species of whales, dolphins, and
porpoises are distributed worldwide.
• Cetaceans have fishlike bodies with
forelimbs modified as flippers.
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• Cetaceans are divided into two groups:
1) toothed whales 2) baleen whales
• Toothed whales include beaked whales,
sperm whales, beluga whales, narwhals,
killer whales, dolphins, and porpoises.
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• Most have over 100 teeth
• Prey on fish, squid, seals and
other whales
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• Baleen whales lack teeth
• Baleen-thin plates of finger like
material; acts as strainer for
feeding
• Shrimp and other small
invertebrates are the prey of
baleen whales.
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The Order Sirenia is made up of four
species of manatees and dugongs.
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• Front limbs are flippers for
swimming
• Sirenians lack hind legs but have
flattened tails.
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Carnivora
• 250 living species in Carnivora
distributed worldwide
• Most of the species eat meat, which
explains the name.
• About 34 species are pinnipeds
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• Some members of
this order, such as
bears, feed
extensively on plant
material, with some
meat, and are
called omnivores.
• Carnivores generally
have long canine
teeth, strong jaws,
clawed toes.
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Pinnipedia
• Pinnipedia are water dwelling
carnivores with streamlined bodies
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Artiodactyla and Perissodactyla
• Ungulates-hoofed mammals, classified
into two orders: Artiodactyla and
Perissodactyla
• These two classes are herbivores.
• They have a storage chamber in their
stomach called the rumen. Food
undergoes double digestion.
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Ungulates with an even amount of
toes make up the class
Artiodactyla
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Ungulates with an odd number of
toes make up the class
Perissodactyla.
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Proboscidea
• Characterized by a boneless nose or
proboscis
• Elephants are the largest land
dwellers alive today, weighing more
than 6 tons.
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They have modified incisors, called
tusks, for digging up roots and
stripping bark from branches.
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Primates
• 200 living species of primates,
classified as prosimians.
• Traditionally primates are divided into
two groups- Prosimians which include
lemurs, lorises, and tarsiers and;
Anthropoids which include monkeys,
apes, and humans.
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• A complex brain has enabled
anthropoids to develop behaviors
conducive to living in highly
organized social groups.
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Environmental Interaction
•
•
•
•
•
4,600 species
Occupy most every environment
Highly adaptive
Very diverse
Most affected by humans
– Biomedical research
– Domestication
– Food source
– Endangered/Extinct
Environmental Interaction
• Predator, prey, scavenger,
herbivore, omnivore, carnivore
• Some migrate for food and
reproduction
• Population size is very
dependent on external stimuli
– Mammals can exhibit huge population
fluctuations – mice, rabbits,
lemmings
• Can be very territorial
Endangered Species
• Causes
• Habitat loss
• Predation
• Interspecies
competition
• Disease
• Exploitation
• Unknown causes
Endangered Species Act
Signed in 1973 by President Nixon
1,000 animals are currently on this
endangered list