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Mammals

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Class Mammalia

The name mammalia is derived from mammary glands. These glands produce milk to nourish newborns. Females are the only sex that produce milk, but males also possess these glands. Males just don’t have certain increases of hormones that cause lactation or milk production.

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Class Mammalia• Hair• Mammary glands• Sweat glands• Muscular diaphragm• Endothermic• Four chambered heart

• Two sets of teeth(“baby” and “adult”)

• Heterodont teeth– Different shapes and

functions

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Class Mammalia

Additional characteristics (you don’t need to write these down)

• Movable eyelids• Two occipital condyles• Three ear bones• Placenta

– Except two groups

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Mammals are endothermic. They maintain a constant internal body temperature. Hair and a subcutaneous fatty layer helps to maintain warmth, while sweat glands help cool.

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Movement

• Backbone that flexes vertically and side to side

• Variations in limb bones allow walking, running, climbing, burrowing, hopping, swimming, flying, etc.

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Basic Mammal

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Lion

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Rhinoceros

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Gorilla

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Chimpanzee

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Chimp and Human

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Bat

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Same bones, different stance

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Feeding and Digestion

• Mammals may be herbivores, carnivores, omnivores, or filter feeders (baleen whale).

• They have specialized teeth• Some mammals that eat plant material have

specialized organs to break down plant material including a rumen and cecum

• The mammalian digestive system cannot break down plant material on its own. Symbioitic relationships with bacteria and fungi allow plant material to be digested in mammalian organs.

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Incissors

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Canine

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Premolars

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Molars

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Grass eaters have different teeth than carnivores

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SALIVARY GLANDS

• DIGESTION starts in the MOUTH

Image from: http://www.entnet.org/healthinfo/throat/salivary.cfm

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BALEENThin keratin plates

that hang from the roof of the mouth and screen food from water

Image from: http://home.iprimus.com.au/readman/whale.htm

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RUMEN

In cud chewers like cows, sheep, goats, giraffes

First chamber of stomach containing bacteria to digest plants

Image from:http://arbl.cvmbs.colostate.edu/hbooks/pathphys/digestion/herbivores/rumen_anat.html

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CECUM

In non cud chewers like horses, rabbits, rodents, elephants

Small pouch off small intestine containing bacteria to digest plants

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Human Digestive System

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Respiration

• Mammals have a large diaphragm muscle that when contracted, pulls the bottom of the chest cavity downward, increasing the volume of the chest cavity, allowing a mammal to inhale.

• Air is pulled into the chest cavity and lungs when this happens.

• When the diaphragm muscle relaxes, the volume of the chest cavity decreases and causes air to be pushed out—exhaling.

Human Respiratory system

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Circulatory system

• Mammals have a two loop closed system (pulmonary and systemic) that is very efficient at transporting oxygen to cells and removing carbon dioxide from cells.

• 4 chambered heart

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Fig. 31.12

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Mammal Circulation

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Excretory system

• Mammals have highly developed kidneys that help maintain homeostasis.

• Kidneys osmoregulate, maintaining water and ion concentrations, as well as removing excess urea or nitrogenous waste from the blood.

Human excretory system

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Nervous system and response• Mammals have the most highly developed

brain of any animal. The three main parts of the mammalian brain are the cerebrum (motor movement, sensory info), cerebellum (balance and coordination), and medulla oblongata (involuntary organ control).

• Mammals have a cerebral cortex, the center for thinking and complex behaviors

• Mammals have exceptional senses such as smell, hearing, and eyesight.

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Reproduction and development• Distinct separate sexes, sexual reproduction,

and internal fertilization.• Most viviparous (duck billed platypus is

oviparous and lays eggs)

• Young nourished by mother’s milk and usually raised for an extended period of time.

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There are 3 general groups of mammals. Include in notes general characteristics for each as well some common examples.

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Monotremes

• Lay eggs• Transitional species• Incubate 12 days• Lick milk from

mothers fur

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MONOTREMES“Egg laying”

Duckbilled PlatypusAnteaterEchidna

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Marsupials

• Pouched mammals• Birth to tiny embryo

that is not fully developed

• Embryo crawls into mother’s pouch to complete development

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MARSUPIALSPremature babies develop in pouch

Mostly found in Australia/ New Guinea

• Kangaroo

• Wallaby

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MARSUPIALSOnly North American Marsupial

• Oppossum

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Placental Mammals

• Placenta nourishes embryo inside mother

• Long gestation period– 22 months for

elephant

• Most successful group of mammals

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PLACENTALEmbryos nourished inside mother

by placenta

95% of all mammals are placental

At least 18 orders

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Placental Mammals

• Competitive advantage over monotremes and marsupials– Better nutrition from

placenta– Less vulnerable to

predators• More advanced at birth

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Evolution of Placenta from Amniotic Egg (you don’t have to write down)

Reptile • Chorion

– Oxygen from air

• Amnion– Provides private pond

• Yolk Sac– Food for embryo

• Allantois– Store urinary waste

• Mammal• Chorion

– Form placenta to get oxygen & food from mothers blood

• Amnion– Provides private pond

• Yolk sac– Temporarily make RBCs

• Allantois– Form umbilical cord

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Mammal Classification

• 14 major orders• Over 4,000 species• About half are rodents• Don’t worry about

writing down various order names and groups

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Order Monotremata

• Lays eggs• Young lick milk from

mothers fur

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Order Marsupiallia

• Pouch

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Order Insectivora

• Sharp-snout• Small• Burrow underground• Eat insects

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Order Chiroptera

• Flying mammals• Elongated fingers• Echolocation

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Order Xenarthra

• Toothless or peg like teeth

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Order Carnivora

• Large canine teeth• Teeth adapted to

shear flesh

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Order Rodentia

• Chisel-like incisor teeth

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Order Lagomorpha

• Four upper incisors• Hind legs adapted for

jumping

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Bats

• Only flying mammal• Seed dispersal• Pollination• Control insects

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Smallest Mammal

• Kitti’s hog-nosed Bat• Bumble size• 1.5 grams

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ECHOLOCATIONBats can fly without eyes, but

NOT without ears

Bats emit high frequency sound waves that bounce off objects

Can determine size, distance, direction, speed

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Echolocation

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Order Cetacea

• Front limbs modified into flippers

• No hind limbs• Marine

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Whales

• Blue whale• 100 feet long, 120 tons

– 9 story building

• Loudest animal– 188 dB• Sound travels 100’s of miles

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Grey Whale

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Migrates 12,500 miles

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Grey Whale

• 50 feet long• 35 tons• Baleen whale

– Sift mud

• Endangered species

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Killer Whale

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Blue Whale

• Baleen whale• Eats krill

– Tiny crustaceans– 400 pounds/day

• Heart weighs 1000 pounds– Size of a Volkswagen

• Endangered species

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Breaching

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Killer Whale

• 12,000 pounds• Eat fish, squid, seals

and whales– 200 pounds/day

• Swim 30 mph

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Humpback Whale

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Order Pinnipedia

• Limbs modified for swimming

• Marine carnivores

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Order Proboscidea

• Tusks• Largest living land

mammal

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Order Artiodactyla

• Two or four toes

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Order Perissodactyla

• One or three toes

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Order Primates

• Opposable thumb• Binocular vision• Well developed cerebrum• Fingers and toes,

fingernails usually• Arms rotate around

shoulder joint• Mammary glands

reduced to one thoracic pair

Write down general characteristics of primates below

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PRIMATES Larger Brain

Grasping hand with fingernails instead of claws

2 forward facing eyes

Includes:•Gorillas•Monkeys•Lemurs

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PRIMATESHumans are

primates too!

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The End

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References

• Content and slides taken from:

• Seth Garrison the great

• Professor Dennis Anderson at Oklahoma City Community College

• Kelly Riedell and her zoology website

• Prentice Hall Biology 2002

• McGraw Hill Zoology 2008