Mammals
Class Mammalia
• Most have an active metabolism
• Endothermic
• Has mammary glands that produce milk
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Let's recap!!
Amphibians have moist skin.
Reptiles have scales.
Birds have feathers.
Mammals have hair!
Functions of Hair
Reduces loss of heat by radiation
Keep out coarse dust particles
Eyelashes, hair in nasal chambers, ear
canals
Functions of Hair
Sex differentiation
Lions, beard and moustaches
Protects from environmental factors
Efficient respiratory and circulatory systems
(4 chambered heart)
Right side of heart
brings in oxygenpoor blood
Left side of heart
brings in oxygenrich blood
Pulmonary Circulation - Blue
Pulmonary –
refers to lungs
Gas exchange
occurs to change
oxygen-poor
blood to oxygenrich
Systemic Circulation - Red
Systemic– refers
to the rest of the
body
Oxygen-rich blood
is taken to top
and lower half of
the body.
Diaphragm helps with lungs
Inhalation – diaphragm
contracts, enlarging the
thoracic cavity (ribcage in the
chest)
Exhalation – diaphragm
relaxes, decreasing thoracic
cavity
Reproduction
• Most are born and not
hatched
• Internal fertilization
• Embryo develops in the
uterus
• Uterus forms a placenta
Brain
• Usually larger
• Capable of learning
• Care for young longer to
teach them skills
• Needed for survival
http://serendip.brynmawr.edu/bb/kinser/Size1.html
Feeding
• Teeth come in a variety
of shapes and sizes
that are adapted to eat
different kinds of foods
– Incisors and caninesshearing or tearing
– Premolars and molarsgrinding
Feeding
• Jaws that are different
from reptiles
• More fused and less
cranial kinesis
(movement of the jaw)
Major Orders of Mammals
» Monotremes
» Marsupials
» Placentals
Monotremes
• Comes from the greek word
monos (single) trema (hole).
• Have a cloaca
• Lack teeth as adults
• Have a spur on the legs in
the ankle region that
contains venom (only in
males) in a platypus.
• Legs are on the sides of
their bodies like reptiles
instead of underneath the
body like most mammals.
Monotremes
• Platypuses and Echidnas (spiny
ant eaters)
– Only mammals that lay eggs
• Contain yolk to nourish young
– Have hair and produce milk
– No nipples-glands secrete milk on
stomach and the babies suck milk
from fur
– Found in Australia and New Guinea
– Infant echidnas are known as
puggles.
Marsupials
• Opossums, Kangaroos,
Bandicoots, and Koalas
– Born very early in development
and completes embryonic
development while nursing
– Young are held in a pouch called a
marsupium
• Example: The red kangaroo is the
size of a honeybee at birth and is
born 33 days after fertilization.
– It then crawls from the exit of the
reproductive tract to the pouch
– Front limbs are more developed at
the time of birth for climbing.
Marsupials
• Reproduction
– Females have 2 vaginas
that lead to two separate
uteruses
– Females have a third
canal that is used for birth
– Males have a pronged
penis that is only used to
transfer sperm (not used
for urination).
– Both sexes have a cloaca
Placentals
• Gets it’s name from the
placenta
– Organ that transfers nutrients,
oxygen, carbon dioxide, and
wastes between mother and
embryo
– Allows the embryo to develop
for a longer time period inside
the mother
• Rats: a few weeks
• Elephants: two years
Mammal
Length of Gestation Period
Opossum (American)
12-13 days
Mouse and Rat
21 days
Rabbit
30-35 days
Guinea Pig
68 days
Human
254-294 days
African Elephant
660-760 days
12 Major Orders
• Insectivores (shrews, hedgehogs, moles)
– Insect eaters
– Have long narrow snouts and sharp claws for
digging
• Sirenians (Manatees, dugongs)
– Herbivores
– Live in rivers , bays and warm costal waters
scattered throughout most of the world
– Slow, large, fully aquatic mammals
12 Major Orders
• Cetaceans ( Whales, dolphins)
– Live underwater but must come to the surface to
breathe
– Most live and breed in the ocean
• Chiropterans (Bats)
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Winged mammals
Only mammals that can fly
1/5 of all mammalian species
Eat mostly fruit, insects, or nectar but some feed on
the blood of other vertebrates
12 Major Orders
• Rodents (Mice, rats, voles, squirrels, beavers,
porcupines, gophers, chipmunks, gerbils, prairie
dogs, chinchillas)
– Have a single pair of long, curved incisor teeth in
upper and lower jaws
– Gnaw wood and other tough plant material
• Perissodactyls (horses, tapirs, rhinoceroses, and
zebras)
– Hofed animals with an odd number of toes on each
foot
12 Major Orders
• Carnivores (dogs, foxes, bears, racoons,
walruses)
– Stalk or chase prey by running or pouncing, then kill
with their sharp teeth or claws
– Some eat plants and meat
• Artiodactyls (Cattle, sheep, goats, pigs, ibex,
giraffes, hippopotami, camels, antelope, deer,
gazelles)
– Hoofed mammals have an even number of toes on
each foot
– Mostly large grazing animals
12 Major Orders
• Lagomorphs (hares and rabbits)
– Herbivores
– Only have a pair of incisors in the upper jaw
– Most have hind legs adapted for leaping
• Xentharthrans (sloths, anteaters and
armadillos)
– Have simple teeth without enamel
– Some have no teeth at all
12 Major Orders
• Proboscideans (elephants)
– Animals with trunks
– Used to include mastodons and mammoths,
but today we only have African and Asian
elephants
• Primates (lemurs, tarsiers, apes, gibbons,
macques, humans)
– Have a highly developed cerebrum and
complex behavior
Primates
• Early primates
– Insectivores
– Cretaceous period
– Probably small and tree dwelling because they had
limber shoulders to swing on trees and hands to hang
on branches
– Claws were replaced with nails
– Sensitive, long fingers and toes
– Eyes are close together in front of their face
(binocular vision)
– Have depth perception that helps with swinging
– Increased parental care
Primates
• 2 Sub orders
– Prosimians “premonkeys”
• Lemurs, lorises, pottos,
and tarsiers
• More like early primates
– Anthropoids
• Monkeys, apes, and
humans
• Fossils indicated they
were already
established in Africa
and Asia 40 mya
Prosimians
• Small
• Nocturnal primates with large eyes
adapted to see in the dark
• Many have dog-like snouts
Anthropoids
• Anthropoid means “human-like primates”
• Branched into two based on evolutionary
history
• New World monkeys and Old World
monkeys
Monkeys
• Came to South America by raft (continents
were closer together then) or by migration
New World Monkeys
• Arboreal-live and
swing on trees
– Have long prehensile
tails that coil around
branches
– nostrils that open to
the side
Old World Monkeys
• Ground dwelling and
arboreal
– Tail is not for swinging
and the nostrils open
downward
– They also have tough
seat pads on their
behinds
– Most are diurnal
(active during the day)
– Usually live in bands
– Hominids are larger
Hominids (or “Great Apes”)
•
Have 4 Genera
1. Hylobates (gibbons)
2. Pongo (orangutans)
3. Gorilla (gorillas)
4. Pan (chimpanzees)
5. Humans
Hominids
• Are larger than monkeys
• Long arms, short legs, and no
tails
• All apes can swing from
branches
– Only gibbons and orangutans
are arboreal
• Gorillas and chimpanzees are
very social
• Apes have proportionally larger
brains than monkeys
• Apes behavior is more
adaptable
• Can walk upright and grasp
with thumbs