Zoology – MAMMALS

THINGS YOU NEED TO KNOW FROM THIS CHAPTER…

1. Classification of Mammals
1. What phylum do mammals belong to?
2. What class do they belong to?
3. Memorize the 11 orders of mammals from your notes and the example mammals of those orders.

i. I suggest that you make flashcards. Put the example mammals on one side and the order names on the other. Then start practicing by flipping through them.

2. What is the critical sign of being a mammal?
1. What are the many functions of hair?
3. Are all mammals placental?
1. What is a placenta?
2. What always nourishes mammalian newborns?
4. How many extant mammal species are there?
5. What did mammals of the late Triassic Period look like?
1. What does diphyodont mean?
2. What does endothermic mean?
3. What glands did these mammals have to have since they had hair?
4. Why did these mammals diversify (or radieate)?
5. What were the keys to their success?
6. Do mammals molt?
1. Why do mammal coats have various colors, spots, and stripes?
2. What are vibrissae?
3. Can a porcupine shoot quills in defense?
7. What is the difference between horns and antlers?
1. What animals have true horns?

i. Are horns branched?

ii. Are they shed?

iii. Are they found in both sexes?

2. Which mammalian family produces antlers?

i. Are they found in both sexes?

ii. What happens as the animals get older?

3. Why isn’t the rhinoceros horn a true horn?
7. From what are all mammalian integumentary glands derived?
1. What are the difference between the following glands…

i. Eccrine sweat

ii. Apocrine sweat

iii. Scent glands

iv. Sebaceous glands

v. Mammary glands

9. Teeth
1. What is the difference between homodont & heterodont dentition?

i. Which condition exists in mammals?

2. What are the following teeth used for in mammals?

i. Incisors

ii. Canines

iii. Premolars

iv. Molars

10. What do we call insect eaters?
1. How long are their digestive tracts?
11. What do we call plant eaters?
1. How are their teeth different than other mammals?
2. What is a diastema?
3. What is cellulose?

i. How do mammals get energy from it?

4. What is a cecum?
5. What does coprophagus mean?
6. What is unique about ruminants?
7. How long are the digestive tracts of plant eaters?
11. What do we call meat eaters?
1. How long are their digestive tracts?
2. As a general rule, are they intelligent animals?
12. What do we call generalists that eat plant and animal matter?
13. Finish the following sentence with increases &/or decreases.
1. As an animal ____ in body weight its food intake per body size ____.
14. Do mammals migrate?
15. What unique hunting strategy is utilized by bats?
1. How is nocturnal different from crepuscular?
16. What is estrous and how does it help baby mammals survive?
1. Differentiate between the following terms…

i. Proestrus

ii. Estrus

iii. Metestrus

iv. Diestrus

18. What is menstruation
19. What are monotremes?
1. Give an example monotreme mammal.
20. What are marsupials.
1. Finish the following statement with shorter &/or longer.

i. They have a ______ gestation period and a ______ lactation period.

2. What is unique about the timing of kangaroo births?
20. What are placental mammals?
1. Finish the following statement with shorter &/or longer.

i. They have a ______ gestation period and a ______ lactation period.

2. What’s strange about human development?
21. List some examples of domesticated mammals.
22. Why are rodents particularly troublesome to humans?
23. What transmits and carries bubonic plague & typhus?
24. What transmits and carries tularemia?
25. What transmits and carries Rocky Mountain spotted fever?
26. What transmits and carries lyme disease?
27. How do humans become infected with trichina worms and tapeworms?

CLASSIFICATION OF MAMMALS

Phylum Chordata

Class Mammalia (** Only select orders, listed below, need to be

memorized.**)

Order Marsupialia – viviparous pouched mammals – opossums,

kangaroos, et al.

Order Chiroptera – bats

Order Primates – monkeys, apes, humans, et al.

Order Xenarthra – armadillos, anteaters, et al.

Order Lagomorpha – rabbits, hares, et al.

Order Rodentia – squirrels, rats, et al.

Order Cetacea – whales, dolphins, et al.

Order Carnivora – dogs, wolves, cats, bears, et al.

Order Proboscidea – elephants

Order Perissodactyla – odd-toed hoofed mammals – horses,

zebras, rhinoceroses, et al.

Order Artiodactyla – even-toed hoofed mammals – swine, deer,

cattle, sheep, goats, et al.

I. Features and Diversity

A. Overview

1. ______________________ is a critical sign of being a mammal.

2. Hair serves many functions: protection, concealment,

waterproofing and buoyancy, signaling, sensitive vibrissae and

especially thermal insulation.

3. Mammals have other characteristic features.

a. Most have a specialized ______________________ to

feed the embryo.

b. The mammal nervous system is more advanced than in

other animal groups.

c. ____________________________________________

nourish the newborn.

B. Diversity

1. About ______________________ living species are known.

2. Nevertheless they are the most highly differentiated group in the

animal kingdom.

II. Origin and Evolution of Mammals

A. History

1. The evolution of mammals from their earliest amniote ancestors

is very fully documented.

2. Over the last 150 million years, small, ectothermic, hairless

ancestors evolved into today’s endothermic, furry mammals.

3. Early Mammals of the ______________________ Period

a. The earliest mammals of the late Triassic were small and

mouse- or shrew-sized.

b. They were ______________________; teeth were

replaced only once as deciduous and permanent teeth.

c. They were almost certainly ______________________

although cooler than modern placental mammals.

d. Hair was essential and also indicates that

____________________________ and

____________________________ were present.

e. There is no fossil evidence but mammary glands must

have evolved before the end of the Triassic.

f. Young early mammals must have hatched from eggs and

relied on maternal milk.

g. Mammals, having developed in the mid-Triassic, had to

wait 150 million years to diversify.

4. ______________________ Radiation of Mammals

a. Mammals survived first as ______________________

______________________ animals, then in a radiation in

the Eocene Epoch.

b. The radiation is attributed to the many habitats vacated by

extinction of many amniote groups (including dinosaurs) at

the end of the Cretaceous.

c. Mammals were agile, endothermic, intelligent, adaptable,

and gave birth to young they protected.

III. Structural and Functional Adaptations of Mammals

A. Integument and Its Derivatives

1. Skin

a. Mammals skin is generally thicker than in other classes of

vertebrates.

b. As with all vertebrates, skin is made of epidermis and

dermis.

c. In mammals, the dermis becomes much thicker than the

epidermis.

d. The epidermis is thinner and well protected by hair.

e. In places that are subject to abrasion, the outer layers

become thicker and cornified with keratin.

2. Hair

a. Hair is characteristic of mammals; it is reduced on

humans and exists as a few bristles on whales.

b. Dense and soft underhair serves for insulation by trapping

a layer of air.

c. Coarse and longer guard hairs protect against wear and

provide coloration.

d. Hair stops growing at a certain length; it remains in the

follicle until new growth pushes it out.

e. In most mammals, there are periodic

______________________ of the entire coat.

1) Foxes and seals shed once every summer.

2) Most mammals molt twice, in the spring and in the

fall, with the winter coat much heavier.

3) Some have white winter coats for camouflage and

brown summer coats.

f. Patterns including spots, stripes, salt-and-pepper, etc. are

disruptive and conceal the animal.

g. ______________________ or “whiskers” are sensory

hairs; they provide a tactile sense to nocturnal mammals.

h. Porcupine, hedgehog, and echidna quills are barbed and

break off easily.

3. Horns and Antlers

a. True Horns

1) Horns are found in ______________________

such as ______________________ and

______________________.

2) Horns are hollow sheaths of _________________

______________________.

3) They embrace a core of ___________________

rising from the skull.

4) They are not normally shed and are not usually

branched, but may be greatly curved.

5) Horns grow continuously and are found in both

sexes, although they may be longer in males.

b. Antlers

1) Antlers are formed in the _______________ family.

2) Antlers are composed of solid bone when mature.

3) Antlers develop beneath an annual spring covering

of highly vascular soft skin or “velvet.”

4) Except for caribou, only _____________ produce

antlers.

5) When growth is complete just before breeding

season, the blood vessels constrict and the stag

removes the velvet by rubbing it against trees.

6) Antlers are shed after the breeding season and a

new bud appears for the next growth.

7) Each year, the new pair of antlers is ___________

than the previous set.

c. Rhinoceros Horn

1) Hairlike keratinized filaments arise from dermal

papillae and are cemented together.

2) These structures, however, are not attached to the

skull.

4. Glands

a. Mammals have the greatest variety of

______________________ glands; all are derived from the

______________________.

b. ______________________ glands are tubular, highly

coiled glands found in mammals but never in other

vertebrates.

c. ______________________ Sweat Glands

1) Eccrine glands secrete a watery fluid that draws

______________________ away from the skin

surface.

2) They are found in ______________________

regions such as footpads.

d. ______________________ Sweat Glands

1) Apocrine glands open into a ________________

______________________.

2) In humans, they develop near puberty and are

restricted to armpits, external ear canals, etc.

3) In contrast to watery secretions of eccrine glands,

apocrine secretions form a film on the skin.

4) Apocrine glands are unrelated to heat regulation

and are correlated with ______________________

______________________.

e. ______________________ Glands

1) Present in nearly all mammals, they vary greatly in

location and function.

2) They communicate with members of the same

species: mark territory, warning and defense.

f. ______________________ Glands

1) Usually intimately associated with

______________________, onto which they secrete

their oil.

2) Cells accumulate fats, then die and are expelled to

form oily sebum.

3) It does not turn rancid but serves as a dressing to

keep the skin and hair pliable and glossy.

4) Most mammals have sebaceous glands over the

entire body.

g. ______________________ Glands

1) Mammary glands are probably modified

______________________ glands.

2) They are rudimentary in males and occur on all

female mammals.

B. Food and Feeding

1. Mammals exploit a wide variety of food sources; some are

specialists and others are generalists.

2. Mammal structures are closely associated with adaptations for

food finding or capturing.

3. Teeth

a. Structure or teeth reveal the life habits of a mammal.

b. Reptiles had ______________________ dentition or

uniform tooth patterns.

c. Differentiation of teeth for cutting, seizing, gnawing, etc.

resulted in ______________________ dentition.

d. Types

1) ______________________ have sharp edges for

snipping or biting.

2) ______________________ are specialized for

piercing.

3) ______________________ have compressed

crowns with one or two cusps for shearing and slicing.

4) ______________________ have larger bodies and

variable cusp arrangements for crushing and grinding.

4. Feeding Specializations

a. ______________________ - Shrews, moles, anteaters

and most bats are insectivores.

1) They eat little fibrous vegetable matter so their

digestive tract is ______________________.

b. ______________________ - Browsers and grazers

include horses, deer, antelope, cattle, sheep and goats.

Gnawers include rodents, rabbits and hares.

1) Herbivores have reduced or absent canines but

molars are broad and high-crowned.

2) ______________________ – gap between

premolars and incisors.

3) ______________________ is a molecule produced

by plants that makes their cell walls rigid. This is

where most of the nutrition is stored, but the chemical

bonds are difficult to break.

4) Herbivores use anaerobic fermentation chambers

so ______________________ can metabolize

cellulose.

5) A side pocket or ______________________ may

also serve as a fermentation chamber and absorptive

area.

6) Hares, rabbits, and some rodents eat fecal pellets

in order to provide additional fermentation.

(______________________)

7) ______________________ have a huge four-

chambered stomach.

8) Food is regurgitated, re-chewed, and passed to the

rumen, reticulum, omasum and abomasum.

9) Herbivores generally have

______________________ digestive tracts for

the prolonged time needed to digest fiber.

c. Carnivores

1) Most carnivores feed on herbivores.

2) A high protein diet is easily digestible and therefore

the digestive tract is ______________________.

3) Carnivores do not have to continuously graze and

they have more leisure time.

4) Capturing prey also requires more intelligence,

stealth, and cunning.

5) In turn, this has driven herbivores to have keen

senses and escape behaviors.

d. ______________________ - pigs, raccoons, rats, bears

and most primates including humans

1) Omnivores feed on both plant and animal tissues.

2) Food supplies in temperate regions vary by

season; migration and hibernation are solutions.

3) Some mammals cache food stores during times of

plenty, a common behavior of rodents.

5. Body Weight and Food Consumption

a. The smaller the animal, the greater is its metabolic rate

and the more it must eat per unit size.

b. The amount of food varies in proportion to the body

surface area rather than the body weight.

1) A 3 gram mouse will consume per gram of body

weight five times more food than does a 10 kilogram

dog and about 30 times more food than does a

50,000 kilogram elephant.

c. Small mammals must spend much more time hunting and

eating food than do large mammals.

d. A small shrew weighing 2 grams must eat more than its

body weight each day and will starve if deprived of food for a

few hours.

e. In contrast, a mountain lion may kill an average of one

deer a week.

C. Migration

1. Fewer mammals than birds make migrations; most remain in a

home range.

D. Flight and Echolocation

1. Mammals have not exploited the skies extensively; bats can fly

and some mammals glide from trees.

2. Bats are ______________________ (active at night) or

______________________ (active at twilight).

3. Echolocation, along with flight, allows bats to navigate and eat

insects in total darkness at night.

4. Bats use frequencies from 30,000 to 100,000 Hz (cycles per

second), well beyond our hearing range.

5. Ten to 200 pulses of signals are sent to locate prey; an echo is

received before the next pulse is sent.

6. Some moths have evolved ultrasonic detectors to detect and

avoid approaching bats.

7. All bats are nocturnal although fruit-eating bats use sight and

olfaction to locate food.

8. Flowers that are evolved to utilize bats as pollinators have smelly

white flowers that open at night.

9. The tropical vampire bat has razor-sharp incisors and

anticoagulant saliva.

E. Reproduction

1. Reproductive Cycles

a. Most mammals have mating seasons timed to coincide

with most favorable time to rear young.

b. Female mammals usually restrict mating to a fertile period

during the periodic ______________________ cycle.

c. This time of female receptivity is known as

______________________ or estrous.

d. Stages of the Estrous Cycle

1) ______________________ is the period of

preparation when new follicles grow.

2) ______________________ is when mating occurs;

this is timed to be simultaneous with ovulation.

3) If pregnancy does not occur, estrus is followed by

______________________, a period of repair.

4) During ______________________, the uterus

becomes small and anemic until the cycle repeats.

e. Menstrual Cycle

1) Old World monkeys and humans have a cycle

terminated by ______________________.

2) Menstruation involves shedding of the

______________________ or lining of the uterus.

2. Reproductive Patterns

a. Egg-Laying ______________________

1) Monotremes such as the ___________________

______________________ lay eggs with one

breeding season per year.

2) She lays eggs in a burrow nest where they are

incubated for 12 days.

3) Similar to reptiles and birds, there is no gestation

and the egg provides all nutrients.

4) However, after hatching, young suck milk from the

mother’s fur near her mammary glands.

b. Pouched ______________________

1) Marsupials are pouched, viviparous mammals.

2) ______________________ is brief and marsupials

give birth to tiny young that are still embryos.

3) Early birth is followed by a prolonged interval of

______________________ and parental care.

c. ______________________ Mammals

1) ______________________ are viviparous

placental mammals.

2) They have an investment in a prolonged gestation

in contrast to marsupials with an investment in

prolonged lactation.

3) Humans are slower developing than any other

mammal; this contributes to our uniqueness.

d. Patterns

1) The ultimate number of young produced per year

also depends on mortality rate.

2) Small rodents that are prey for carnivores usually

produce more than one litter each season.

3) Meadow mice can produce up to 17 litters of four to

nine young each year!

4) At the other extreme, an elephant produces on

average four calves during her 50-year life.

F. Mammalian Populations

1. A population of animals includes all members of a species that

can potentially interbreed in a region.

2. All mammals live in ecological communities with other animal

and plant species.

IV. Humans and Mammals

A. Domesticated Animals

1. ______________________ were probably the first domesticated

animals, being an adaptable offspring of social wolves.

2. The domestic ______________________ is probably derived

from an African race of wildcat.

3. Nomadic people probably subdued ______________________,

______________________, ______________________ and

______________________.

4. Some totally domesticated animals no longer exist as wild

species (e.g. dromedary camel, llama).

5. Many have been selectively bred to yield characteristics

desirable for human purposes.

B. Mammals, Crop Damage and Human Disease

1. ______________________ and ______________________ are

major pests of growing crops and stored foods.

2. Human monocultures and the elimination of predators have

made this a more severe problem.

3. Many rodents carry diseases.

a. House rats and prairie dogs carry ___________________

______________________ and ______________________.

b. ______________________ is transmitted to humans by

wood ticks and carried by rabbits and other rodents.

c. ____________________________________________ is

carried to humans by ticks from ground squirrels and dogs.

d. Ticks from white-tailed deer transmit

____________________________________________.

e. Trichina worms and tapeworms are acquired by humans

who eat meat of infected mammals.