Class MammaliaPages 557 - 573

Mammalia is one of the smallest classes under Kingdom Animalia

However, it contains most of what we call “animals” today

Mammalia also contains humans There are 26 orders under Class Mammalia

(12 are under placental mammals)

Class Mammalia

6 Main Characteristics:◦ Breathe air (they have lungs)◦ Are endothermic (warm-blooded: cold room does

not equal cold mammal)◦ Have 4 chambers (sections) to their hearts◦ Have specialized teeth (different teeth for

different jobs)◦ Produce (make) milk for their young◦ Have hair

Characteristics of Class Mammalia

2 Kinds of mammal hair:◦ Underhair: soft, insulating fur next to the skin; it

keeps the animal warm◦ Guard hair: coarse (hard and strong), longer, and

found over the underhair; gives the animal color◦ *Whiskers: a special kind of guard hair with

nerves around the roots of the hair – these allow animals to feel what is around them

◦ Some other guard hairs can also have nerves at the base and feel things

Mammalia Hair

Mammals can be carnivorous (lions), herbivorous (cows) or omnivorous (humans)

Almost all mammals will have some kind of teeth

Different teeth do different jobs

Digestion in Mammals

Three basic kinds of teeth:◦ Incisors – flat, thin teeth at the front of the mouth

used for gnawing or biting◦ Canines – rounded, pointed teeth toward the front

of the mouth used for tearing◦ Molars – thick, squat teeth in the back of the

mouth used for grinding and chewing

Kinds of Teeth

Herbivorous (plant eaters) have a special, longer digestive tract to let the food break down

Some, like the cow, have a rumen: a bag at the top of the stomach with spit, where the food goes to get wet◦ After being mixed with the spit, the cow will throw

up the food into its mouth (food is now called cud) and chew it again to get it to break down even more

Digestion in Herbivorous Mammals

Cow Digestion VS. Horse Digestion

Some, like horses, have a cecum: an extra bag where the food sits in spit for an extra few hours to break down even more before becoming poop

Digestion in Herbivorous Mammals

All mammals will have lungs to breathe oxygen

These lungs are controlled by a muscle called a diaphragm◦ The diaphragm pulls the lungs down to pull air in

and goes up to push air out The air passes through a larynx inside the

throat◦ The larynx gives the animal its voice

Respiration in Mammals

All mammals have 4 chambers in their hearts

The heart is very strong, like in Class Aves and Class Reptilia

Circulation in Mammals

All mammals are endothermic – they can control their own body temperature

Many mammals lose body heat through their skin, but some do other things◦ Dogs pant and lose heat through their tongues◦ Elephants can lose heat through their ears◦ Pigs and elephants can lose heat by rolling in the

mud

Endothermic

Many mammals hibernate (sleep deeply in winter)

Squirrels and woodchucks will hibernate in winter – they sleep deeply, become very cold, and their body systems slow down, they can’t wake up easily

Bears and badgers become dormant – they sleep deeply, but they can’t wake up if they are bothered – they do not HIBERNATE!

Hibernating

Mammals have brains and can think for themselves

Mammals have memories and can learn well

Some mammals seem to show emotions These things come from a part of the brain

called the Cerebrum – the biggest part of the brain

Response in Mammals

Mammals can reproduce one of three ways1.) Placental Mammals – their babies develop

(grow) inside the mother’s uterus and are connected to the mother through a placenta

The umbilical cord connects the baby to the placenta and is cut when the baby is born

Gestation is the name of pregnancy in these mammals

Cats, dogs, horses, humans All of the orders we will study are placental

mammals

Reproduction in Mammals

2.) Marsupial Mammals: mammals with pouches◦ Babies are made inside the mother, but do not

have a placenta – they have a small yolk sac for food instead

◦ After the yolk sac is gone, the babies go into a marsupium (pouch/bag) on the mother and drink her milk until they are old enough to be out on their own

◦ Kangaroos, koalas, wombats, opossums◦ Marsupials usually live in Australia (but also China

and America)

Reproduction in Mammals

Monotreme Mammals: mammals that lay eggs and sit on them to keep them warm until they hatch (ovoparous NOT viviparous)◦ Monotremes feed their babies with milk, but do

not have nipples – their milk gets put onto their skin and the babies lick it off

◦ The most common monotreme is the platypus

Reproduction in Mammals

These mammals have well-developed, continuously growing incisors (flat, thin teeth at the front of the mouth)

If they don’t chew on something hard, those teeth can grow into their brains

Beavers, mice, squirrels

Order Rodentia

Well-developed canine teeth (rounded, pointed teeth used for tearing)

Claws on toes Carnivorous Cats, dogs, bears, lions, tigers

Order Carnivora

They have four fins (legs/arms for swimming)

Marine environments – they live in the water

Carnivorous Seals, walruses

Order Pinnipedia

Marine mammals – live in the water Dorsal blowholes – a hole on the back used

to breathe Horizontal flukes – arms used for swimming

on both sides of the body Use echolocation – they send out sound

waves to figure out what is in front of them Whales, dolphins

Order Catacea

Binocular vision – can see near and far away

Erect stature – they stand up and walk on their back legs

Opposable thumbs – their thumbs can bend to grab things

Apes, monkeys, humans

Order Primates

Odd-toed ungulates – mammals with hooves that either have one toe or three toes

They have a cecum – a bag where food sits in spit to break down

Herbivorous – they only eat plants Horse, donkey, zebra, rhinocerous

Order Perissodactyla

Even-toes ungulates – have hooves with two toes

They can have a cecum or rumen (bag on top of the stomach where food gets spit put on before being thrown up into the mouth to be chewed again)

Pigs, cows, hippopotamuses, deer

Order Artiodactyla

Leviticus 11 told the Jewish people what to eat◦ Cloven footed beasts (even-toed hooves)◦ Chew the cud (have a rumen)

What did Jews eat?

Teeth undeveloped or absent (not there) Unique (special) back vertebrae (hard, wide

plates instead of round vertebrae) Anteaters, armadillos, sloths

Order Edentata

Flying mammals Use echolocation (they send out sound

waves to figure out what is in front of them) Bats

Order Chiroptera

Mainly insectivorious (they eat insects) Live underground Shrews, moles, hedgehogs

Order Insectivora

Live in coastal areas (where the land and water meet) in tropical and semitropical waters (Hawaii, India, Vietnam, Philippians)

Called Sea Cows Manatees, dugongs

Order Sirenia

Long, boneless trunk (long nose) Largest land mammals Elephants and Mammoths Mammoths are now extinct (they are all

dead)

Order Proboscidea