Mammals. Class Mammalia Small number of species ~4500 But probably more successful than most animal groups (except insects) at exploiting all available

MammalsMammals

Class MammaliaClass Mammalia

Small number of species ~4500

But probably more successful than most animal groups (except insects) at exploiting all available environments

Small number of species ~4500

But probably more successful than most animal groups (except insects) at exploiting all available environments


Very diverse group not constrained by particular lifestyle (like flight in birds)

Diversity makes it difficult for layperson to identify various mammals as being closely related

Very diverse group not constrained by particular lifestyle (like flight in birds)

Diversity makes it difficult for layperson to identify various mammals as being closely related


Descended from therapsid reptiles with mammal-like characteristics

Important structural changes from reptiles to mammals

Descended from therapsid reptiles with mammal-like characteristics

Important structural changes from reptiles to mammals


Limbs from lateral to ventral

Higher center of gravity - less stability

Required greater development of cerebellum - muscular coordination center in brain

Limbs from lateral to ventral

Higher center of gravity - less stability

Required greater development of cerebellum - muscular coordination center in brain


Separation of air and food passageways in head

Can breathe with mouth full of food

Allows prolonged chewing & some early digestion

Separation of air and food passageways in head

Can breathe with mouth full of food

Allows prolonged chewing & some early digestion

Subclass TheriaSubclass Theria

Most mammals belong to Subclass Theria

Descended from some common ancestor ~150 million years ago

Most mammals belong to Subclass Theria

Descended from some common ancestor ~150 million years ago

Subclass TheriaSubclass Theria

Infraclass Metatheria - marsupials - pouched mammals

Infraclass Eutheria - placental mammals

Infraclass Metatheria - marsupials - pouched mammals

Infraclass Eutheria - placental mammals

Subclass PrototheriaSubclass Prototheria

Monotremes Small group of egg-

laying mammals So different from

other groups of mammals

Entirely different origin?

Monotremes Small group of egg-

laying mammals So different from

other groups of mammals

Entirely different origin?

All mammalsAll mammals

Characteristics unique and diagnostic for mammals

Hair - greatly reduced in aquatic mammals

Mammary glands - milk secreting glands for nourishing young

Characteristics unique and diagnostic for mammals

Hair - greatly reduced in aquatic mammals

Mammary glands - milk secreting glands for nourishing young

Integument & DerivativesIntegument & Derivatives

Skin generally thicker than in other vertebrates

Dermis thicker than epidermis

Epidermis very thin where covered with hair, thicker on palms, soles

Skin generally thicker than in other vertebrates

Dermis thicker than epidermis

Epidermis very thin where covered with hair, thicker on palms, soles


Hair derived from epidermis

Probably evolved from reptilian scales

Scales still present in some (tail of rat, beaver)

Hair derived from epidermis

Probably evolved from reptilian scales

Scales still present in some (tail of rat, beaver)


Grows from follicle Epidermal structure

sunk deep into dermal layer and beyond

Grows by addition of new cells at base of follicle

Grows from follicle Epidermal structure

sunk deep into dermal layer and beyond

Grows by addition of new cells at base of follicle


Cells pushed upward die from lack of nourishment

Dead cells mostly keratin - same material in nails, claws, feathers

Cells pushed upward die from lack of nourishment

Dead cells mostly keratin - same material in nails, claws, feathers


Hair consists of 3 layers Medulla - core Cortex - contains

pigment Cuticle - composed of

imbricated scales Different types of hair

result from differential development of the 3 layers

Hair consists of 3 layers Medulla - core Cortex - contains

pigment Cuticle - composed of

imbricated scales Different types of hair

result from differential development of the 3 layers


Each follicle has muscle attached to it - erector muscle

Contraction causes hair to stand up straight

Increase insulation thickness, serve as warning

Each follicle has muscle attached to it - erector muscle

Contraction causes hair to stand up straight

Increase insulation thickness, serve as warning

Fur or PelageFur or Pelage

Most mammals have two kinds of hair

Thick, soft underhair - provides insulation

Coarse, long guard hair - protects and provides coloration

Most mammals have two kinds of hair

Thick, soft underhair - provides insulation

Coarse, long guard hair - protects and provides coloration


Hair stops growing when it reaches certain length

Remains in follicle until new growth starts, then falls out

Hair stops growing when it reaches certain length

Remains in follicle until new growth starts, then falls out


Mammals lose hair in periodic molts

Most have 2 annual molts - entire pelage shed (humans shed and replace continually)

Spring - thin summer Fall - heavy winter

Mammals lose hair in periodic molts

Most have 2 annual molts - entire pelage shed (humans shed and replace continually)

Spring - thin summer Fall - heavy winter


Pigmentation and molts allow mammals to be different colors in different seasons

Brown in summer White in winter -

leukemism

Pigmentation and molts allow mammals to be different colors in different seasons

Brown in summer White in winter -

leukemism


Lack of pigment results in albinism - recessive gene - blocks pigment formation (don’t confuse with leukemism)

Excess of black pigment is melanism

Lack of pigment results in albinism - recessive gene - blocks pigment formation (don’t confuse with leukemism)

Excess of black pigment is melanism

Derivatives of HairDerivatives of Hair

Vibrissae - sensory hairs on snouts, other parts of head

Incorrectly called whiskers

Vibrissae - sensory hairs on snouts, other parts of head

Incorrectly called whiskers

Derivatives of HairDerivatives of Hair

Quills - defensive structures in porcupines, hedgehogs, echidnas

Break off after barbed tip embeds in flesh of other animal

Work in deeper with time

Quills - defensive structures in porcupines, hedgehogs, echidnas

Break off after barbed tip embeds in flesh of other animal

Work in deeper with time

GlandsGlands

Mammals also have variety of epidermal glands

Greatest variety among vertebrates

4 basic types

Mammals also have variety of epidermal glands

Greatest variety among vertebrates

4 basic types

GlandsGlands

Sweat glands - simple, tubular, highly coiled

Cover most of body Not found in other

vertebrates Open directly to skin

surface Two types

Sweat glands - simple, tubular, highly coiled

Cover most of body Not found in other

vertebrates Open directly to skin

surface Two types

GlandsGlands

Sweat glands - eccrine glands

Secrete watery sweat for temperature regulation

Hairless regions in most mammals (especially foot pads)

Sweat glands - eccrine glands

Secrete watery sweat for temperature regulation

Hairless regions in most mammals (especially foot pads)

GlandsGlands

Some mammals don’t have eccrine glands - rodents, rabbits, whales

Some have them all over body - humans, horses, dogs

Racial differences in abundance in humans

Some mammals don’t have eccrine glands - rodents, rabbits, whales

Some have them all over body - humans, horses, dogs

Racial differences in abundance in humans

GlandsGlands

Sweat glands - apocrine glands

Found in all mammals Longer, more winding

than eccrine glands Open into follicle at

surface Secretion not involved

with heat regulation

Sweat glands - apocrine glands

Found in all mammals Longer, more winding

than eccrine glands Open into follicle at

surface Secretion not involved

with heat regulation

GlandsGlands

Apocrine gland activity correlated with some aspects of sexual cycles

Human females have twice as many as males

Apocrine gland activity correlated with some aspects of sexual cycles

Human females have twice as many as males

GlandsGlands

Scent glands - location and function vary

Communication, warning, defense, attraction

E.g., skunk Humans have many,

but taught to dislike their scent

Scent glands - location and function vary

Communication, warning, defense, attraction

E.g., skunk Humans have many,

but taught to dislike their scent

GlandsGlands

Sebaceous glands - associated with hair follicle

Secrete fat (sebum) to keep hair and skin soft

Polite fat - does not turn rancid

Generally all over body - most numerous on human scalp, face

Sebaceous glands - associated with hair follicle

Secrete fat (sebum) to keep hair and skin soft

Polite fat - does not turn rancid

Generally all over body - most numerous on human scalp, face

GlandsGlands

Mammary glands - modification of apocrine, sebaceous glands?

Present in both genders, functional only in female

Secrete milk to nourish young

Mammary glands - modification of apocrine, sebaceous glands?

Present in both genders, functional only in female

Secrete milk to nourish young

GlandsGlands

Contain varying quantities of fat (3-5%), protein, carbohydrate, salts

Higher fat content (30-40%) in marine and arctic mammals, where development is rapid

Contain varying quantities of fat (3-5%), protein, carbohydrate, salts

Higher fat content (30-40%) in marine and arctic mammals, where development is rapid

Horns & AntlersHorns & Antlers

3 kinds of horns or horn-like structures found in mammals

1) true horns 2) antlers 3) rhino horns

3 kinds of horns or horn-like structures found in mammals

1) true horns 2) antlers 3) rhino horns


True horns Found in ruminants

like cows, goats, antelope

Hollow sheaths of keratinized epidermis surrounding core of bone arising from skull

True horns Found in ruminants

like cows, goats, antelope

Hollow sheaths of keratinized epidermis surrounding core of bone arising from skull


Not normally shed Not branched (but

may be greatly curved, twisted)

Found in both sexes

Not normally shed Not branched (but

may be greatly curved, twisted)

Found in both sexes


Antlers Deer family

(Cervidae) Generally males only

(except caribou - female’s smaller)

Entirely bone when mature

Antlers Deer family

(Cervidae) Generally males only

(except caribou - female’s smaller)

Entirely bone when mature


Annual growth Develop beneath

cover of highly vascularized soft skin - velvet

Growth complete, blood vessels constrict, velvet dies and is rubbed off

Annual growth Develop beneath

cover of highly vascularized soft skin - velvet

Growth complete, blood vessels constrict, velvet dies and is rubbed off


Antlers dropped after breeding season

New buds appear within few months

New pair larger, more elaborate

Strain on mineral metabolism - moose, elk must accumulate 50+ lbs of calcium salts from vegetable diet

Antlers dropped after breeding season

New buds appear within few months

New pair larger, more elaborate

Strain on mineral metabolism - moose, elk must accumulate 50+ lbs of calcium salts from vegetable diet


Rhinoceros horn Hairlike horny fibers

arise from dermal papillae

Cemented together to form single horn

Dagger handles and medicinal uses

Rhinoceros horn Hairlike horny fibers

arise from dermal papillae

Cemented together to form single horn

Dagger handles and medicinal uses

TeethTeeth

Teeth are a less obvious characteristic of mammals

Reveal more about lifestyle than any other characteristic

Not in monotremes, some whales, anteaters

Teeth are a less obvious characteristic of mammals

Reveal more about lifestyle than any other characteristic

Not in monotremes, some whales, anteaters

TeethTeeth

Diphyodont teeth - two sets of teeth Set of deciduous “milk teeth” replaced by set of

permanent teeth Reptiles have polyphyodont teeth - many sets -

all are homodont - uniform, unspecialized

Diphyodont teeth - two sets of teeth Set of deciduous “milk teeth” replaced by set of

permanent teeth Reptiles have polyphyodont teeth - many sets -

all are homodont - uniform, unspecialized

TeethTeeth

Mammals have heterodont teeth - specialized for various functions

Mammals have heterodont teeth - specialized for various functions

TeethTeeth

TeethTeeth

Incisors - snip, bite - simple crowns, slightly sharp edges

Incisors - snip, bite - simple crowns, slightly sharp edges

TeethTeeth

Canines - piercing - pointed, long conical crowns Canines - piercing - pointed, long conical crowns

TeethTeeth

Premolars - shear, slice - flat compressed crowns with 1 or 2 cusps

Premolars - shear, slice - flat compressed crowns with 1 or 2 cusps

TeethTeeth

Molars - crushing, grinding - broad with variable cusp arrangement

Always belong to the permanent set

Molars - crushing, grinding - broad with variable cusp arrangement

Always belong to the permanent set

TeethTeeth

Different diets necessitate differing development of different teeth

Carnivores - large canines, some small and/or modified molars and premolars

Different diets necessitate differing development of different teeth

Carnivores - large canines, some small and/or modified molars and premolars

TeethTeeth

Rodents and herbivores - large incisors, reduced canines, large molars

Incisors grow continually, must be worn away to keep pace with growth

Rodents and herbivores - large incisors, reduced canines, large molars

Incisors grow continually, must be worn away to keep pace with growth

TeethTeeth

Digestive SystemsDigestive Systems

Different diets also necessitate differing digestive systems

Herbivores face special problem - indigestibility of cellulose, chief carbohydrate in plants

Different diets also necessitate differing digestive systems

Herbivores face special problem - indigestibility of cellulose, chief carbohydrate in plants


No digestive enzyme to break down cellulose

Depend on anaerobic bacteria to do it

Developed various digestive structures where microbes can do their thing

No digestive enzyme to break down cellulose

Depend on anaerobic bacteria to do it

Developed various digestive structures where microbes can do their thing


Two basic approaches

1) hind-gut approach 2) fore-gut approach

Two basic approaches

1) hind-gut approach 2) fore-gut approach


Hind-gut approach Horses and rabbits

and others Large sidepocket -

cecum - at junction of small, large intestines

Houses microbes

Hind-gut approach Horses and rabbits

and others Large sidepocket -

cecum - at junction of small, large intestines

Houses microbes


Sometimes all isn’t digested first time through

Rabbits, hares, some rodents eat fecal pellets - coprophagy

More bacterial fermentation, chance to absorb vitamins manufactured by bacteria

Sometimes all isn’t digested first time through

Rabbits, hares, some rodents eat fecal pellets - coprophagy

More bacterial fermentation, chance to absorb vitamins manufactured by bacteria


Humans have vestigial cecum - appendix

Humans have vestigial cecum - appendix


Fore-gut approach Cattle, deer, sheep,

antelope are ruminants

Have huge, 4-chambered stomach where digestion occurs

Fore-gut approach Cattle, deer, sheep,

antelope are ruminants

Have huge, 4-chambered stomach where digestion occurs


Grass passed down esophagus to rumen

Broken down by bacteria and formed into small balls of cud in reticulum

Regurgitated to mouth and chewed to crush fibers

Grass passed down esophagus to rumen

Broken down by bacteria and formed into small balls of cud in reticulum

Regurgitated to mouth and chewed to crush fibers


Swallowed to rumen again for further digestion by bacteria

Finally passed through reticulum and churned in omasum

Swallowed to rumen again for further digestion by bacteria

Finally passed through reticulum and churned in omasum


Passed into abomasum - true stomach

Proteolytic enzymes secreted, normal digestion occurs

Passed into abomasum - true stomach

Proteolytic enzymes secreted, normal digestion occurs


Small intestine very long, coiled

Much longer in herbivores than in carnivores, insectivores

Cow small intestine - 50+ m (165 feet)

Small intestine very long, coiled

Much longer in herbivores than in carnivores, insectivores

Cow small intestine - 50+ m (165 feet)

Size vs. Food ConsumptionSize vs. Food Consumption

The smaller the mammal, the greater its metabolic rate, and the more it must eat relative to its size

Small mammals spend more time hunting, eating than large mammals

The smaller the mammal, the greater its metabolic rate, and the more it must eat relative to its size

Small mammals spend more time hunting, eating than large mammals


2 g shrew eats > its body weight in food each day

Will starve to death in few hours if deprived of food

2 g shrew eats > its body weight in food each day

Will starve to death in few hours if deprived of food


Large carnivore may only need one meal every few days to remain healthy

Large carnivore may only need one meal every few days to remain healthy

MigrationMigration

Few mammals make seasonal migrations

Much more difficult than for birds

Most that do live in, near North America

Few mammals make seasonal migrations

Much more difficult than for birds

Most that do live in, near North America

MigrationMigration

Barren-ground caribou - seasonal movements >1000 km

North for calving, south for winter

Barren-ground caribou - seasonal movements >1000 km

North for calving, south for winter

MigrationMigration

Longest mammal migrants are whales, seals

Fur seal females migrate 2800 km to give birth, winter

Males stay north

Longest mammal migrants are whales, seals

Fur seal females migrate 2800 km to give birth, winter

Males stay north

MigrationMigration

Few bats with power of flight use it to migrate

Most hibernate during winter

4 spp. of American bats migrate - red bat

Winter in Mexico, summer north, west

Few bats with power of flight use it to migrate

Most hibernate during winter

4 spp. of American bats migrate - red bat

Winter in Mexico, summer north, west

FlightFlight

Flight, gliding evolved independently in several different groups: marsupials, rodents, lemurs, bats

Bats are only true fliers - nocturnal insectivore niche left open by most birds

Flight, gliding evolved independently in several different groups: marsupials, rodents, lemurs, bats

Bats are only true fliers - nocturnal insectivore niche left open by most birds

FlightFlight

Success of bats: 1) flight 2) ability to navigate

via echolocation

Success of bats: 1) flight 2) ability to navigate

via echolocation

EcholocationEcholocation

Fly and avoid obstacles in complete darkness

Locate & catch insects with precision and speed

Find way deep into caves - new habitat

Fly and avoid obstacles in complete darkness

Locate & catch insects with precision and speed

Find way deep into caves - new habitat


Emit short pulses (5-10 msec) from mouth

Ultrasonic to human ear 10-200 pulses/sec Echo received with

great ears - form image of surroundings as good as eyes of other mammals

Emit short pulses (5-10 msec) from mouth

Ultrasonic to human ear 10-200 pulses/sec Echo received with

great ears - form image of surroundings as good as eyes of other mammals


May be used by other insectivorous mammals: shrews, tenrecs

Crudely developed compared to bats

May be used by other insectivorous mammals: shrews, tenrecs

Crudely developed compared to bats


Echolocation highly developed in toothed whales, e.g., sperm whale

Varying frequency clicks produced in sinus passages

Echolocation highly developed in toothed whales, e.g., sperm whale

Varying frequency clicks produced in sinus passages


Focused by lens-shaped melon in forehead

Returning echoes channeled through oil-filled cavity in lower jaw to inner ear

Focused by lens-shaped melon in forehead

Returning echoes channeled through oil-filled cavity in lower jaw to inner ear


Allows whales to determine size, shape, speed, distance, directions, density of everything in water

Keep track of members of pod

Allows whales to determine size, shape, speed, distance, directions, density of everything in water

Keep track of members of pod

HibernationHibernation

True hibernators: ground squirrels, woodchucks

Body temperature falls within few degrees of freezing

Breathing, heart rates drop extremely low

True hibernators: ground squirrels, woodchucks

Body temperature falls within few degrees of freezing

Breathing, heart rates drop extremely low

HibernationHibernation

Not true hibernation: bears

Breathing, heart rates fall, but body temperature remains similar

Not true hibernation: bears

Breathing, heart rates fall, but body temperature remains similar

ReproductionReproduction

Most mammals have definite mating seasons

Usually winter or spring

Timed to coincide with most favorable time for rearing young after birth

Most mammals have definite mating seasons

Usually winter or spring

Timed to coincide with most favorable time for rearing young after birth


Female mating function restricted to time during periodic cycle - estrous cycle

Female receptive during brief period of cycle - estrus or heat

Several other stages

Female mating function restricted to time during periodic cycle - estrous cycle

Female receptive during brief period of cycle - estrus or heat

Several other stages


Proestrus - period of preparation

New ovarian follicles grow

Proestrus - period of preparation

New ovarian follicles grow


Estrus - mating, ovulation, fertilization, implantation, pregnancy

Estrus - mating, ovulation, fertilization, implantation, pregnancy


Metestrus - if no mating or fertilization, a period of repair

Metestrus - if no mating or fertilization, a period of repair


Diestrus - uterus becomes small, anemic

Diestrus - uterus becomes small, anemic


Monestrous - single estrus during breeding season

Dogs, foxes, bats Polyestrous -

recurrence of estrus during breeding season

Mice squirrels, tropical animals

Monestrous - single estrus during breeding season

Dogs, foxes, bats Polyestrous -

recurrence of estrus during breeding season

Mice squirrels, tropical animals


Humans and Old World monkeys have slightly different cycle

Post-ovulation period terminated by menstration - menstrual cycle

Humans and Old World monkeys have slightly different cycle

Post-ovulation period terminated by menstration - menstrual cycle


3 different patterns of reproduction among mammals

1) monotremes 2) marsupials 3) placentals

3 different patterns of reproduction among mammals

1) monotremes 2) marsupials 3) placentals


Monotremes - egg-laying mammals

One breeding season each year

Ovulated eggs (2) fertilized in oviduct

Shell added in oviduct Eggs laid in burrow

nest Incubated for 12 days

Monotremes - egg-laying mammals

One breeding season each year

Ovulated eggs (2) fertilized in oviduct

Shell added in oviduct Eggs laid in burrow

nest Incubated for 12 days


Hatch, fed milk (licking, not suckling)

No gestation - period of pregnancy

Developing embryo uses nutrients in egg

Young reared on milk

Hatch, fed milk (licking, not suckling)

No gestation - period of pregnancy

Developing embryo uses nutrients in egg

Young reared on milk


Marsupials - pouched mammals

Brief gestation period, but physiology and lactation complicated

E.g., red kangaroo

Marsupials - pouched mammals

Brief gestation period, but physiology and lactation complicated

E.g., red kangaroo


1st pregnancy of season followed by 33-day gestation, joey born underdeveloped

Crawls into pouch, attaches to nipple

Mother immediately becomes pregnant again

1st pregnancy of season followed by 33-day gestation, joey born underdeveloped

Crawls into pouch, attaches to nipple

Mother immediately becomes pregnant again


Presence of young in pouch arrests development at 100-cell stage - diapause

Lasts ~235 days until joey leaves pouch

2nd joey develops, born in ~month, enters pouch

Presence of young in pouch arrests development at 100-cell stage - diapause

Lasts ~235 days until joey leaves pouch

2nd joey develops, born in ~month, enters pouch


Becomes pregnant again

Arrested development Oldest joey returns to

nurse from time to time

3 young at once

Becomes pregnant again

Arrested development Oldest joey returns to

nurse from time to time

3 young at once


Some marsupial variations Development delays

Common features Born at

underdeveloped stage

Prolonged development attached to mammary gland

Some marsupial variations Development delays

Common features Born at

underdeveloped stage

Prolonged development attached to mammary gland


Placentals - most successful mammals

Reproductive investment is in gestation

Embryo nourished by food via placenta

Placentals - most successful mammals

Reproductive investment is in gestation

Embryo nourished by food via placenta


Gestation variable Mice - 21 days Rabbits - 30-36 days Cats, dogs - 60 days Cattle - 280 days Elephants - 22 months Baleen whales - 12

months Bats - 4-5 months

Gestation variable Mice - 21 days Rabbits - 30-36 days Cats, dogs - 60 days Cattle - 280 days Elephants - 22 months Baleen whales - 12

months Bats - 4-5 months


Variable condition at birth - well-furred and mobile to naked, blind, helpless

Human growth slower than any other mammal

Variable condition at birth - well-furred and mobile to naked, blind, helpless

Human growth slower than any other mammal

# of Young# of Young

Smaller animals, larger litters

Larger animals, smaller litters

Status in food web important

Carnivores - 1 litter of 3-5 young

Mice - 17 litters of 4-9 young per year

Smaller animals, larger litters

Larger animals, smaller litters

Status in food web important

Carnivores - 1 litter of 3-5 young

Mice - 17 litters of 4-9 young per year

# of Young# of Young

Large mammals - single young with each pregnancy

Elephant - 4 young per 50-year reproductive life

Large mammals - single young with each pregnancy

Elephant - 4 young per 50-year reproductive life

TerritoryTerritory

Defended area for exclusive use

Marked using scent glands

Varies in size from huge (grizzly bear) to small (squirrel)

Defended area for exclusive use

Marked using scent glands

Varies in size from huge (grizzly bear) to small (squirrel)

TerritoryTerritory

Owner comfortable within territory, intruder at “psychological” disadvantage


TerritoryTerritory



TerritoryTerritory

Some territories established for use by family unit

Male beaver defends territory, female and young use it

Some territories established for use by family unit

Male beaver defends territory, female and young use it

TerritoryTerritory

Some live in friendly towns - prairie dog

Parents give old home to young and move out

Some live in friendly towns - prairie dog

Parents give old home to young and move out

Home RangeHome Range

Larger foraging area surrounding defended territory

Neutral zone used for foraging by owners of several territories

Larger foraging area surrounding defended territory

Neutral zone used for foraging by owners of several territories

Us & ThemUs & Them

Biggest impact - domestication

Dogs, cats 10,000 years ago

Food animals much later

Biggest impact - domestication

Dogs, cats 10,000 years ago

Food animals much later

Us & ThemUs & Them

Beasts of burden Some no longer

exist in wild - llama, alpaca, 1-humped Arabian camel

Beasts of burden Some no longer

exist in wild - llama, alpaca, 1-humped Arabian camel

Us & ThemUs & Them

Some not truly domesticated - do not breed in captivity

Reindeer, Asian elephant

Some not truly domesticated - do not breed in captivity

Reindeer, Asian elephant

Us & ThemUs & Them

Problem mammals - rodents, rabbits

Damage crops, foods, carry diseases

Problem mammals - rodents, rabbits

Damage crops, foods, carry diseases

Us & ThemUs & Them

Problems with us 300 species

endangered Includes all cetaceans,

cats, otters, primates Hunting, collecting,

habitat destruction, species introductions

Problems with us 300 species

endangered Includes all cetaceans,

cats, otters, primates Hunting, collecting,

habitat destruction, species introductions

Documents

Mammals. Class Mammalia Small number of species ~4500 But probably more successful than most animal groups (except insects) at exploiting all available