Mammals
General Characteristics
Mammals are Endothermic
animals who use hair, fur and
subcutaneous fat to conserve
heat
Mammals also have Sweat glands to
cool body
With the exception of a few species
all mammals are Viviparous
Mothers have mammary glands to
produce milk to nourish young
The mammary glands are the most
important characteristic
Mammals have Many types of
teeth and well developed breathing
muscles including a diaphragm
Mammals also have a 4 chambered
heart consisting of 2 atria and 2
ventricles.
Evolution of mammals
The first mammals were shrew-like
By the end of the cretaceous period there
were three groups of mammals
3 Groups of Mammals
1. Monotremes – duckbill platypus and
spiny anteater, lay eggs
2. Marsupials – opossum, kangaroo,
wombat, koala – have pouch where young
develop
3. Placental mammals – all mammals we’re familiar
with (humans)
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Carnivores
Canine teeth and claws on feet
Herbivores have developed
Strong lips, tongues and flat edged
incisors and flattened molars to grind
up vegetation
Have stomach compartment called
rumen where a bacteria digests cellulose
Herbivores w/out rumen have cecum
The appendix is a remnant of the cecum
in humans
Respiration
Lungs
Powered by 2 sets of muscles
(chest and diaphragm)
Many have vocal cords to
produce sound
Internal Transport
4 chambered heart that pumps
oxygenated blood to body and
deoxygenated blood to lungs
Excretion
Well-developed kidneys
that control the level of
body fluid
Reponse
Well-developed brain allowing
them to respond to environment
Brain – cerebrum, cerebellum
and medulla
Most mammals don’t see color
well
Most have higher level of
hearing and smell than humans
Movement
4 limbs
Depending on type of
movement the limb will have a
certain structure
Reproduction
Monotremes – oviparous (lay eggs
and incubate them outside body)
Marsupials – viviparous (bear
young alive, egg grows into
embryo outside body in pouch)
Placental – viviparous (placenta
exchanges waste and nutrients
to embryo inside mothers
womb)
Time in embryo is gestation
period
32-2 Monotremes
Monotremes are egg laying mammals and
are very rare. Only six species alive today
Marsupials
Marsupials are pouched mammals. Only the
opossums are found in America. Most
other marsupials are found in Australia
Orders of Placental Mammals
Placenta mammals are placed into sixteen
orders.
Order Insectivora
Insect eating mammals
Shrews, hedgehogs and moles
High metabolic rate and must eat
constantly to stay alive
Order Chiroptera
Many diff. species of bats
Eat insects, fruit, frogs, blood
They use echolocation.
Order Edentata
Mammals without teeth
Anteaters, armadillos, sloths
Feed on insects
Order Rodentia
Rodents have 2 long front teeth that can
chew through wood
Mice, rats, squirrels, beavers, porcupines,
gophers
Constant gnawing keeps teeth worn down
(always grow)
Order Lagomorpha
rabbits
Order Carnivora
Meat eaters
Cats, dogs, weasels, wolves, bears, hyenas, seals
Stalk, chase prey and kill with teeth and claws
Order Cetacea
Whales, dolphins, porpoises
Still breathe air
Developed lungs and circulatory system
allow long dives
Whales have lost ears and hind legs
carnivores
Order Sirenia
Manatee (sea cow)
Lives in rivers and streams
Order Artiodactyla
Large grazing animals
Two toes called even-toed unguluates
(hoofed animals)
Order Perissodactyla
Odd toed ungulates
Zebras, horses, tapirs and rhinos
Order Proboscidea
Mammals with trunks
Order Primates
Humans and apes