Zoology - Unit 6

T/F Mammals are not a large group, but are the most differentiated

true

What is mammal hair made out of

keratin protein

Under hair

dense and soft, insulation to retain body temp

Guard hair

course and long, protection and coloration

How does hair provide sensory info?

vibrissae (whiskers, bristles) attach to nerves

Which family has true horns?

Bovidae family (sheep, cattle, antelopes)

Do true horns shed? branch? grow continuously?

Shed: no

Branch: no

Grow continuously: yes

Which family has antlers?

Cervidae family (deer)

Do antlers shed? branch? grow continuously?

Shed: yes

Branch: yes

Grow continuously: no; grow for limited time in males only

Mammary glands

• secrete milk

• ductal system surrounded by milk producing cells

  • milk secreted through nipples

  • milk is species specific

Sebaceous glands

• excrete sebum lipids to keep skin/hair soft and pliable

  • helps waterproof skin

Eccrine glands

• secrete watery fluid

• allows for temp regulation (perspiration)

• not all animals have eccrine glands

  • found in hairless areas of body

Apocrine glands

• secrete milky odorous fluid

  • scent glands

  • used for communication

• develop during sexual maturation

• location is species specific

What jaw muscles allow for up-down movement? side-side?

up-down: adductor muscles

side-side: temporalis and masseter

Heterodont teeth

different types/shapes of teeth for different function

Diphyodonts

have baby teeth and adult teeth

Where is olfactory information processed?

cerebral cortex

Insectivores

• feed on insects and other invertebrates

• short intestinal tract

• teeth to crush through exoskeleton

• shrews, moles, bats, anteaters

Herbivores

• feed on grass and other vegetation

• no canine teeth, premolars/molars adapted for grinding

• digesting cellulose requires specific anaerobic bacteria that produce cellulase

• very long digestive tract

• eat continuously throughout day

Non-ruminants

fermentation occurs either in colon or cecum (elephants, horses)

Ruminants

fermentation occurs in 4 chambered stomach (bison, antelope, giraffes)

Carnivores

• feed on other vertebrates

• large canine teeth, premolars/molars adapted to shearing muscle away from bone

• short digestive tract

• large, discrete meals

Omnivores

• feed on both plant and animals

• versatile teeth

• rounded molars for crushing

• pigs, bears, primates

Mammal 4 chambered heart pathway

DO blood into RA then RV, then out lungs to be O, then O blood returns to LA then LV, then fully O blood out to heart

What ensures rhythmic heartbeat in mammals?

sinoatrial node

Do mammal red blood cells have a nucleus?

No; allows each cell to contain more hemoglobin

What does the loop of henle help with?

able to concentrate urine to maintain osmoregulation

Wing vs. Patagium

Wing: modified hand/paw with membrane skin extending to back limbs (true flight)

Patagium: skin that extends from sides of body to front and back limbs (gliding flight)

Monoestrous

one estrus cycle per breeding season (fox, wolves, bats)

Polyestrous

recurrent estrus cycles per breeding season (most mammals)

Monotremes

• one breeding season/year

• platypus, echidnas

• embryos develop in uterus for 10-12 days

• thin, leathery shell secreted around embryo

• young hatch in 12 days and underdeveloped

• mammary glands but no nipples

  • young lap up milk excreted on fur

Marsupials

• kangaroos, opossums, tasmanian devils, koalas

• pouched viviparous animals

• short placental gestation

  • embryos born underdeveloped and complete development in pouch

• kangaroos have embryonic diapause

  • when embryo moves to pouch, female can get pregnant again

  • can have three offspring at all diff stages of development at the same time

Eutherians/Placentals

• viviparous placental

• prolonged gestation

  • gestation length inc with body size

• placenta connects embryo to mother’s uterus

• once born young are either altricial or precocial

• mother produces milk for young to nurse

Altricial

blind, sometimes hairless, helpless

Precocial

have fur, eyes open, able to move around

Ultimate causation

• why

• evolutionary explanation

• how does behavior inc relative fitness

Proximate causation

• how

• physiological explanation

Innate behavior

• instinctual

• genetic component

• independent of environmental influence

Learned behaviors

• occur as result of experience

• adapt to changes in environment

Kinesis movement

undirected movement in response to stimulus

Taxis

directed movement towards or away from stimulus

Fixed action pattern (innate)

movement that occurs in response to stimulus, still continues when stimulus is changed or removed

Migration (innate)

long range seasonal movement of animals

Foraging (innate)

movement in search for food/water (optimal foraging patterns to max energy gain and min energy loss)

Three innate behaviors involved in animal interactions

• communication

• altruistic behavior

• mating rituals

Communication signals

• chemical (pheromones)

• aural (sounds)

• visual (courtship and aggressive displays)

• tactile (touch)

Altruism

behaviors that lower fitness of individual exhibiting the behavior and inc the fitness of another individual

Intersexual selection

individuals of one sex choose mates of other sex

Intrasexual selection

competition for mates within the same sex

Monogamous

one male and one female

Polygynous

one male with multiple females

Polyandrous

one female with multiple males

Two types of learned behaviors

• habituation

• imprinting

Habituation

simple form of learning in which an animal stops responding to stimulus after repeated exposure

Imprinting

simple form of learning occurring at specific age or life stage