Chapter 16

Mammals

Animals-Vertebrates-Mammals

On the fifth and sixth days of creation God created a new kind of being: “the moving creature that hath life.” Genesis 1:20

Genesis 1:20-25 describes the two main attributes of the animal kingdom: mobility and diversity.

Mobility and Diversity

Animals are living organisms that move from place to place in their environment, mainly for the purpose of obtaining food.

Most animals are motile – they move from place to place.

Some animals are sessile – they are stuck in one place, but are able to move food toward themselves.

Mobility and Diversity

There are over one million known and classified species of animals alive today.

Symmetry in the Animal Kingdom

Three types of symmetry:

1. Bilateral – organism can be cut in half and be the same on both halves

2. Radial – cut in half in many ways and all the halves will be the same

3. Asymmetry – changing shape constantly – no symmetry

Vertebrates: Animals with Backbones

Zoology is a broad study that is divided into smaller parts…

two of these parts are:1. vertebrates – animals with

backbones2. invertebrates – animals without

backbones

Vertebrates make up only 3% of all animals and include: mammals, birds, reptiles, amphibians, and fish

Characteristics of Vertebrates

• Endoskeleton – made of bone or cartilage

• Tetrapods – most have four appendages

• Bilateral symmetry

• Phylum Chordata – modern evolutionists place vertebrates into this larger group.

Mammals

• Warmblooded • Hair• Mammary glands (produce milk)• Lungs• Four-chambered heart• Most are born alive• Most have two pairs of limbs and seven

neck vertebrae

Mammals

Mammals have many characteristics in common, but there are differences in structure of the design.

Example: Elephants have incisors, but they take the form of tusks.

Temperature Regulation• Animals are classified as either warmblooded or

coldblooded.• A warmblooded animal does not necessarily

have warmer blood than a coldblooded animal.• The difference?

a warmblooded animal regulates its temperature by internal mechanisms

a coldblooded animal must regulate its temperature by external mechanisms

• All mammals are considered warmblooded.

Temperature Regulation

• Homeothermic – warmblooded animals are able to maintain the same temperature

• Hibernation – small animals like squirrels cannot gather enough food in the winter to maintain warmth and so will hibernate.

if disturbed they will not wake up• Winter Sleep – larger animals like bears sleep in

the winter to maintain warmthif disturbed they will wake up

Mammals and Nature

• Mammals are important to man as helpers and food.

• Mammals are important to nature in that they keep a balance in population of animals and plants.

• Carnivores prey upon herbivores and thus keep plant populations from dwindling.

Mammal Reproduction

• Fertilization – mammals reproduce by sexual fertilization

• In sexual reproduction a reproductive cell from a male unites with a reproductive cell of a female.

• The male cell (a sperm) is produced in the organ called testes.

• The female cell (an egg) is produced in the organ called ovaries.

Mammal Reproduction

• The eggs enter a tube called the oviduct

it is here where fertilization takes place

• Some mammals like cats and dogs release several eggs for fertilization, others like horses generally only one.

Mammal Reproduction

• Cell Division

- The oviduct leads to a organ called the uterus

- in the uterus the fertilized egg (now already several cells large) attaches to the wall via a placentia

Mammal Reproduction

Embryonic Development At the time of attachment the developing

mammal is now called an embryo.

The embryo forms three layers called primary germ layers:1. Ectoderm – Outer layer – will specialize into the

nervous system, sensory organs, and skin.2. Mesoderm – middle layer – will specialize into muscle,

bone, blood, lymph vessels, reproductive organs, and kidneys.

3. Endoderm – inner layer- will specialize to become the digestive system, respiratory tract, urinary bladder, and urethra.

Mammal Reproduction

• The embryo grows and develops nourished by the placenta and surrounded by amniotic fluid for protection.

• Once the embryo is recognizable it is called a fetus.

• The entire time from fertilization and birth is called the gestation period.

for hamsters a period of 16 daysfor elephants a period of 2 years!

Mammal Reproduction

• At birth the umbilical cord will be cut by the mother freeing the newborn from the mother.

• Mammals that then nourish their young during development are called viviparous.

Mammal Reproduction

Non-placental mammals two orders of mammals are not nourished thru a

placenta1. Monotemata

young are expelled in an egg-like shell.these oviparous mammals do not bear live

young.Examples: duckbill platypus – the babies lap up

milk from the mother.2. Marsupials

Young attach to the mother in a pouchExample: kangaroos, opposums

Three Major Categories of Mammals

Based upon the way the developing young are nourished:

1. Placental mammals

2. Egg-laying mammals

3. Pouched mammals

The Mammalian Orders

There are about 20 mammalian orders comprising 4000 species…

Order Tububildentata

Contains only one species: The aardvark

designed for two things:

digging holes and eating termites and ants

Order Proboscidea

Only two species:African elephants and Asian elephants

They are the largest living land mammal, but there are over 300 species in fossils

Elephants are herbivores and a bull male can eat 300 lbs of food a day!!

Order Proboscidea

Tusks are made from ivory and are enlarged incisor teeth.

Their teeth wear down over time, but are replaced 5 times over their lifetime.

Order Sirenia

• Often called “sea cows”• Include manatees and

dugongs

• Dugongs live in smaller seas like the red sea

• Manatees are larger and live in larger coastal waters around the Caribbean and Florida.

Order Monotremata

• The only oviparous (egg-laying) mammals in existence

• Includes the echidna (spiny anteater) and the duckbill platypus

• Both only live in Australia, New Guinea, and Tasmania

Order Edentata

• Armadillos, Sloths, and Anteaters

Order Pholidota

• Pangolins (scaly anteater)

• Live in southeast Asia, Indonesia, and parts of Africa south of the Sahara

Order Marsupialia

• The pouched mammals

• Includes kangaroos, opossums, wombats, koalas, and numbats

Order Insectivora

• Includes 300 species• Includes shrews,

hedgehogs, and moles

• The smallest mammal is believed to be the pigmy shrew.

Order Chiroptera

• The flying mammals – bats

• Echolocation system: Contrary to popular opinion, bats can see very well…but they also have a sonar system to locate insects.

• Scientist think that this system is so unique that the bats are able to actually create a mental picture of the insect.

Order Chiroptera

• In the summer in Bracken Cave near San Antonio, Texas, the 20 million bats that live there consume 250 tons of insects every night.

Order ChiropteraBats

• Behavioral Characteristics: - Bats are timid and do not generally attack

people - Some bats are fruit eaters - Bats are nocturnal - Bats in cold regions are known to spend

longer periods of time in hibernation than any other mammal

- vampire bats do drink blood, but it is the blood of cattle – the only danger to the livestock is the rabies virus that many bats carry

Order Cetacea

Marine Mammals:

Includes: Baleen whales – they sift their food

Blue whales – largest animal

Sperm whale and killer whale – both have teeth

Dolphins – use echolocation

Order Cetacea

This order gives birth to live young.

The whaling industry in the United States ceased in 1971.

kwintro.mov

Order Primata

Tree Dwelling Mammals

Includes 166 species…monkey, apes, chimpanzees, orangutans, gibbons, and gorillas...lemurs and others…

Order Primata

Apes: Primates without tails…

The largest is the mountain gorilla of the volcanic mountain ranges of East Africa (Congo)

The smallest ape is the gibbon.

Considered the most intelligent is the chimpanzee…

Order Primata

Monkeys

Monkeys are divided into two groups…New world and old world monkeys.

New world monkeys live in the tropical forests of Central and South America as well as Africa and Asia

They possess a prehensile tail (a tail for grasping objects)

They include spider monkeys and howlers as well as others…

Order Primata

Monkeys

Old world monkeys are noted for their close nostrils.

They live in Africa and Asia only…

They include colobus monkeys, baboons

They mostly eat leaves…

Order Primata

Lemurs:

Live only in one area – Madagascar

They eat some insects as well as leaves, fruit, and bark

Order Rodentia

Gnawing Mammals

1700 species…Including: mice, rats, capybara,

squirrels, woodchucks, gophers, beavers, porcupines…

There are more rodents than there are all other mammals combined.

Order Rodentia

Mice: mice are the most prolific animal…they produce 5 or more litters of 3 to 12 young every year..

Rats: rats are aggressive…they are impossible to kill off…if their numbers become low, the survivors become stronger and more productive

rats are a great health concern as they carry many diseases (plague, food poisoning, and typhus)

Order Rodentia

Woodchucks (groundhog): make tunnels and mounds several feet high.

Beavers: largest rodent in U.S…have been known to build dams up to 2300 feet wide.

Porcupines: even with their barbs, they are still preyed upon by carnivores and owls.

woodchuck

Order Dermoptera

Flying lemers

Found in Malaysia, Thailand, Borneo, Java, and the Philippines.

The longest gliding mammal.

Order Lagomorpha

Hare-like mammals:

Have four upper incisors…

Includes rabbits, hares, and pikas

Order Hyracoidea

This order includes only the hyrax…

It is mentioned in the Bible…Proverbs 30:26.

They have hoofs on their toes and pads on the sole of their feet.

They are defenseless and live in rocky terrains for protection.

Order Perissodactyla

Odd-toed hoofed mammals

Hoofed animals are called ungulates.

Includes rhinoceros, tapirs, horses, zebras, and donkeys

Most ungulates have been designed as swift runners, because they need to escape from predators.

Order Artiodactyla

Even-toed hoofed animals

There are 171 species of even-toed ungulates.

Many either have antlers or horns…

They include cattle, buffalo, sheep, goats, and antelope – with horns

and deer – with antlers

It also includes the giraffe.

Order Artiodactyla

This order is the most important on the earth, providing a link between man’s use and also the use by a number of flesh eating animals.

Order CarnivoraFlesh eaters!!!!

Carnivores lead a more active life than herbivores.

There are over 200 species of carnivores.

Includes bears, cats, dogs, foxes, raccoons, weasels, seals, walruses, sea lions, pandas, skunks, badgers, otters, mongooses, civets, and hyenas.

Carnivores eat herbivores and lack a complex stomach.

Carnivores eat separate meals and have time in between to play, explore, and develop their hunting skills.

Order Carnivora

Bears

Bears are actually omnivores – they eat plant and meat

The Alaska brown bear (Kodiak bear) is the largest bear – they are a type of grizzly bear.