Title: Biology - Chapter 33
1Biology - Chapter 33Mammals
- Charles Page High School
- Stephen L. Cotton
2Section 33-1 Mammals
- OBJECTIVES
- Describe the characteristics of mammals.
3Section 33-1 Mammals
- OBJECTIVES
- Discuss the importance of endothermy in the
evolution of mammals.
4Section 33-1 Mammals
- The animals known as mammals vary greatly in
appearance - from a tiny mouse to a huge elephant
- flying in the air running along the ground
swimming in the sea - but, Class Mammalia does have certain
characteristics
5Section 33-1 Mammals
- Mammals are
- endothermic animals (generate body heat
internally) - experts at maintaining a constant body
temperature, because of subcutaneous fat - also have sweat glands to help cool the body as
it evaporates
6Section 33-1 Mammals
- Most mammals are viviparous- develop inside the
mother for a time, and are then born alive
however, a very few primitive varieties lay eggs
(oviparous) - female mammals have mammary glands which produce
milk for the young - have hair or fur at some time
7Section 33-1 Mammals
- Mammals have several kinds of teeth that either
bite, chew, or grind food with efficient jaws - scientists use the teeth of a mammal to classify
it into the different mammalian orders - Have well-developed breathing muscles, including
a diaphragm that separates chest abdomen
8Section 33-1 Mammals
- A 4-chambered heart, consisting of 2 atria and 2
ventricles, and a double loop circuit - one circuit moves blood to and from the lungs
- the other circuit moves blood to and from cells
in the rest of the body
9Section 33-1 Mammals
- Evolution of Mammals- the first mammals were
small and probably resembled species of the tree
shrews alive today - Figure 33-4, page 739
- probably nocturnal, active mainly at night
because they were endotherms
10Section 33-1 Mammals
- By the end of the Cretaceous Period, mammals had
split into three groups - 1. Order Monotremata- called monotremes most
primitive 6 species alive today examples are
the duckbill platypus spiny anteater
11Section 33-1 Mammals
- 2. Order Marsupalia- the marsupials
- includes opossums, kangaroos, wombats, and koalas
- each of these species has a pouch (marsupium) in
which its young live for a time to complete
their development
12Section 33-1 Mammals
- 3. Placentals- composed of 16 orders
- includes the mammals we are most familiar with,
such as mice cats whales elephants and humans - hard to say exactly when each of these 3 groups
appeared
13Section 33-1 Mammals
- We do know that the placental mammals experienced
adaptive radiation in North America and Europe - Marsupials experienced adaptive radiation in
Australia, South America, and Antarctica (which
was a good deal warmer then than it is today)
14Section 33-1 Mammals
- Feeding- carnivorous mammals, such as cats and
dogs, developed strong, sharp incisors and
canines that are used for biting and ripping
flesh use an up and down motion of the jaws - may also have sharp claws to grab prey bodies
built for bursts of speed to chase prey
15Section 33-1 Mammals
- Herbivorous mammals, from cows to giraffes, eat
plants that require thorough chewing - have evolved strong lips and flat-edged incisors
that grasp and tear this tough vegetation - move their jaws side to side
- However, it is still difficult to digest the
plant cellulose
16Section 33-1 Mammals
- Many grazing animals (called ruminants) have a
chamber in their digestive tract called the
rumen, in which newly swallowed plant food is
stored and processed for a time - the rumen contains thriving colonies of symbiotic
bacteria that produce enzymes
17Section 33-1 Mammals
- After a time, the animal can then regurgitate the
plant food from the rumen into its mouth - described as chewing their cud
- the second time food is swallowed, it moves
through the rest of the digestive system to
complete digestion
18Section 33-1 Mammals
- Herbivores such as rabbits lack a rumen, but have
a large dead-end sac called the cecum - contains some of the same types of bacteria that
produce the digestive enzymes - ancestors of humans had a cecum, but is now
shrunk into our appendix
19Section 33-1 Mammals
- Other mammals may drink blood, such as vampire
bats - a chemical in saliva keeps the blood from
clotting - Filter feeders- such as the giant blue whale- the
teeth are modified into huge stiffened plates
called baleen, which act like giant filters
20Section 33-1 Mammals
- Respiration- all mammals, even sea mammals, use
lungs powered by two sets of muscles - 1. Chest muscles move ribs
- 2. Diaphragm pulls downward to increase size of
chest cavity and draw air in - many mammals use exhaled air over the vocal cords
for sound
21Section 33-1 Mammals
- Internal Transport- 4-chambered heart pumps
deoxygenated blood to the lungs, and after
returning to the heart it pumps oxygenated blood
to the body tissues - two circuits, one to lungs and the other to the
body, efficiently transport gases and nutrients
22Section 33-1 Mammals
- Excretion- most highly developed kidneys of all
vertebrates - kidneys also control the composition of body
fluids - extract nitrogenous wastes from blood as urea
- urea water excess salts urine flows
through the ureters to the urinary bladder to
store
23Section 33-1 Mammals
- Response- most highly developed brains of any
animals - three parts of the brain
- 1. Cerebrum- thinking, learning
- 2. Cerebellum- coordination
- 3. Medulla- regulate body functions such as
breathing and heart rate
24Section 33-1 Mammals
- Mammals depend on highly developed senses- well
developed sight, hearing, smell - most mammals do not see color well- except for
apes, monkeys, and humans - probably because the first mammals were nocturnal
- human ears not real sensitive
25Section 33-1 Mammals
- Dogs and bats hearing is great
- human taste and smell is also not highly
developed - Mammals depend on complex behavior for protection
- herbivores able to run horns or hooves for
defense band together into groups for protection
26Section 33-1 Mammals
- Movement- four limbs inherited from their
ancestors - running mammals such as horses attain great
speeds - climbing mammals such as monkeys prehensile tail
- flying mammals bats
- aquatic mammals like dolphins
27Section 33-1 Mammals
- Reproduction- the 3 groups of mammals vary
greatly in their methods of reproduction - oviparous monotremes but still provide milk for
nourishment - marsupials have limited yolk sac, so they are
born early and crawl into a pouch (marsupium) to
obtain the milk
28Section 33-1 Mammals
- In placental embryos, the egg membranes develop
into tissues called the umbilical cord, which
join with the mothers tissues at the placenta - the placenta allows the embryo to develop for a
much longer time inside the mother - time is called gestation period
29Section 33-2 Important Orders of Living Mammals
- OBJECTIVES
- Compare methods of mammalian reproduction.
30Section 33-2 Important Orders of Living Mammals
- OBJECTIVES
- Identify the most important orders of placental
mammals.
31Section 33-2 Important Orders of Living Mammals
- OBJECTIVES
- Recognize the importance of mammals in the world.
32Section 33-2 Important Orders of Living Mammals
- Scientists use several traits to classify the
mammals - structure of teeth
- number and kinds of bones in the head
- most important characteristic is the type of
reproduction- we already learned the 3 types
33Section 33-2 Important Orders of Living Mammals
- Order Monotremata- the monotremes are egg-laying
mammals, and are very rare - found in isolated parts of Australia and New
Guinea - examples are the duckbill platypus (p.743) and
spiny anteater (or echidna- p.746)
34Section 33-2 Important Orders of Living Mammals
- Order Marsupalia- the pouched mammals such as
kangaroos and koalas are found in Australia - opossums are the only marsupials found in North
America eat insects, birds - newborn are about the size of a bee- crawl into
the pouch
35Section 33-2 Important Orders of Living Mammals
- Living placental mammals are placed into 16
orders we will study 12 of the most important - in addition to having different reproductive
habits, placental mammals have slightly higher
metabolic rates - more abundant than marsupials
36Section 33-2 Important Orders of Living Mammals
- 1. Order Insectivora- the name means
insect-eater - shrews, hedgehogs, moles
- extremely high metabolic rate eat almost
constantly to stay alive - biologists believe that the first mammals looked
and behaved much like certain modern shrews
37Section 33-2 Important Orders of Living Mammals
- 2. Order Chiroptera- the different species of
bats - some eat only insects
- others eat only fruits
- some feed on blood of other mammals (vampire
bats) - echolocation-navigate at night
38Section 33-2 Important Orders of Living Mammals
- 3. Order Edentata- the name means without teeth
even though some of them have teeth - sloths (South American- slow moving, hang upside
down), anteaters (long tongue, tapered snout
powerful legs to rip open ant nests), and
armadillos
39Section 33-2 Important Orders of Living Mammals
- 4. Order Rodentia- many amusing animals, and some
quite destructive - mice rats squirrels beavers porcupines, and
gophers - all have 2 long front teeth that continually
grow, thus they wear them down by gnawing
40Section 33-2 Important Orders of Living Mammals
- Most rodents are small, and have a short
gestation period - rats and mice are adaptable animals that eat a
wide variety of foods - long ago, these rodents moved in with humans and
have traveled with us the world over
41Trees damaged by beavers.
42Trees damaged by beavers.
43Section 33-2 Important Orders of Living Mammals
- 5. Order Lagomorpha- familiar rabbits and hares
- closely resemble rodents because they have sharp
front teeth and eat plant material - gestation period is short, and the number of
offspring is high - compete with us for food
44Section 33-2 Important Orders of Living Mammals
- 6. Order Carnivora- are meat eaters- dogs, cats,
wolves, bears, weasels, hyenas, seals - most are terrestrial, stalking and chasing their
prey - seals and walruses had at one time land
ancestors, but have since returned to the ocean
45Section 33-2 Important Orders of Living Mammals
- 7. Order Cetacea- the truly aquatic mammals-
whales, dolphins, and porpoises - still breathe air- have lungs and a circulation
designed to permit long, deep dives - have a layer of subcutaneous fat (blubber) to
keep warm
46Section 33-2 Important Orders of Living Mammals
- 8. Order Sirenia- strange aquatic animals related
to elephants - peaceful,slow-moving herbivores in rivers and
streams of Africa, South America, and Florida - the manatee (sea cow) is often injured by
careless boaters
47Section 33-2 Important Orders of Living Mammals
- 9. Order Artiodactyla- large grazing animals
cattle, sheep, goats, hippos, giraffes, pigs - original 5 toes on each foot have been reduced to
2 - called even-toed ungulates (hoofed mammals)
48Section 33-2 Important Orders of Living Mammals
- 10. Order Perissodactyla- horses, zebras, tapirs,
and rhino - these are the odd-toed ungulates
- contains many grazing animals with habits similar
to those of the even-toed ungulates
49Section 33-2 Important Orders of Living Mammals
- 11. Order Proboscidea- mammals with trunks- the
great elephants - formerly included mammoths and mastodons
- today, 2 species the Indian elephant and African
elephant, both in danger of extinction
50Section 33-2 Important Orders of Living Mammals
- 12. Order Primates- which includes our own
species (humans), and is closely related to
ancient insectivores - most highly developed cerebrum, and most
complicated behaviors
51Section 33-2 Important Orders of Living Mammals
- The most primitive living primates, the lemurs,
are small tree dwellers two other main branches
are monkeys and apes - Very early in their evolutionary history,
primates as a group were split apart by the
moving continents
52Section 33-2 Important Orders of Living Mammals
- One branch, the New World monkeys, includes the
squirrel monkey and spider monkey - these live almost entirely in trees
- have long arms for swinging, and a long
prehensile tail for grasping
53Section 33-2 Important Orders of Living Mammals
- The other branch, the Old World monkeys, include
chimpanzees, gorillas, and the ancestors of
humans - many still spend much of their time in trees, but
they all lack prehensile tails
54Section 33-2 Important Orders of Living Mammals
- How Mammals Fit Into the World
- evolved from early reptile ancestors during the
Mesozoic Era about 200 million years ago - herbivores are major plant consumers- grazing
zebras, reindeer herds, oxen
55Section 33-2 Important Orders of Living Mammals
- The herbivores are food for the carnivores-
lions leopards wild dogs wolves - bats eat large numbers of mosquitoes
- squirrels eat nuts and seeds
- domesticated animals for work horses oxen mules
56Section 33-2 Important Orders of Living Mammals
- Many of these animals also provide food in the
form of meat and dairy products - dogs are used to hunt, helping humans find food
- But, some mammals have a negative impact on human
life
57Section 33-2 Important Orders of Living Mammals
- Carnivores prey on domesticated animals
- rodents such as rats and mice damage crops, eat
stored food - some mammals carry diseases, such as rats that
harbor fleas that spread the plague
58Section 33-2 Important Orders of Living Mammals
- Dogs, squirrels, other wild animals that transmit
the virus for rabies - elephants destroy trees as they feed
- overgrazing by cattle turns land into a dust
bowl beavers flood areas - Humans- good or bad influence?