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52 Cards in this Set
- Front
- Back
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When did mammals appear on earth?
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220mya during the Late Triassic period
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What are the skin glands mammals have?
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Mammary glands, sweat glands, sebaceous glands, scent glands
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What is the function of mammary glands?
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Provide nourishment for young, period of association between mother and young during lactation and suckling encourages close social bonds, extremely impt. Time of rapid learning for many species
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Which mammals lack nipples?
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Monotremes
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How do young suck milk from mammary glands?
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from tuft of hair around nipple area
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How do whales, dolphins and porpoises suck milk? what is different about them?
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mothers have muscles that force milk into the mouths of their young, these species have no movable lips and have to feed underwater
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What do sweat glands do?
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a. Watery secretion promotes evaporative
cooling b. Also eliminates some waste |
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What do sebacceous glands do?
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Associated with hair follicles
b. Produce oily/waxy secretion that lubricates the hair and skin |
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What is the function of scent glands?
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Attracting mates
b. Marking territories c. Social interaction d. Protection |
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What is the hair made up of on a mammal?
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Dead epidermal cells
strengthened by keratin |
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What is a pelage?
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a coat of hair
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What is the primary function of pelage?
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a. Both dissipation and absorption are
retarded b. In large, diurnal, open-country mammals (e.g., African antelope) light color of pelage may reflect light thereby decreasing solar radiation intake "INSULATION" |
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Which mammals are hairless? what do they have instead?
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whales and dolphins=have thick blubber
elephants and rhinos, hippos have thick skin and it is favorable mass to surface area |
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What kind of environmental conditions is hair subject to?
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bleaching and wear
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When do mammals undergo molts?
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1-2 times a year and when juveniles gain first adult pelage
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When do North Temp. species molt?
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during spring and fall, and the summer pelage is shorter for less insulation
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What does counter-shading w/ different top side and underside do, sun, and single coloration?
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Typical color pattern = darker on
back and lighter on the underside 2) Sun: back more brightly illuminated 3) Single color pelage would make underside appear darker revealing form of animal |
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What is the function of stripes?
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1)Tend to obliterate shape when
against broken patterns of light and dark 2)Stripes tend to exaggerate size – optical illusion |
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What is the function of facial markings?
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Facial markings reduce
conspicuousness of eyes by disruptive pattern of color |
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What mass extinction are we going through now?
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6th
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What is the difference between metatheria and eutheria?
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metatheria are the closest relatives to marcupials and eutheria are placental mammals
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What does the right side of the heart do? what is this called?
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receives venous blood and pumps it to the lungs; pulmonary circulation
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What does the left side of the heart do? what is this called?
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receives oxygenated blood from the lungs and pumps it to the body at high pressure; systemic circulation
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What kind of erthrocytes do mammals have? what is different about them from other vertebrates?
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have biconcave disks (curve on both sides) rather than have ovoid spheres
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Which animals have different eryrthrocytes? and how are they different? what does this do for them?
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camels extrude their nuclei when mature; increasing of oxygen-carrying capacity to support high metabolic rates
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How is air forced?
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muscular action from diaphragm- expansion in volume= decrease in pressure
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Describe the reproductive system of mammals.
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Both ovaries are functional
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Where are ova fertilized in mammals?
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in uterine tubes
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Where does the embryo develop in mammals? And within what?
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In the uterus and within a fluid-filled amniotic sac
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How is the embryo nourished?
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From a maternal blood stream via the placenta
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What does the scrotum do in the reproductive system for mammals?
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Sperm cannot mature at the deep body temperature so the scrotum serves as a cooler- the testes are typically scrotal
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What is the greater size of the brain in mammals due to?
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The cerebral hemispheres
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What is the neopallium?
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Mantle of gray matter that has expanded over the deeper, primitive vertebrate brain
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How has the neopallium in mammals greatly increased?
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Because of the complex pattern of folding
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Which mammals will have more acute smell? Which ones have poorly developed sense of smell?
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Mammals w/ nocturnal ancestry, in higher primates (diurnal) and in whales
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Which mammals have an absent sense of smell?
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Dolphins and porpoises
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What is the tapetum lucidem? Which animals is it well developed in?
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Dense layer of reflective cells & crystals within choroid reflect light back to retina; well developed in nocturnal species; it results in “eyeshine” in deer when light is shined at them in night
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What are pinnae?
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External ears- mammals have them
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What are vibrissae?
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Whiskers on muzzle and stiff hairs on head, lower legs.
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What does skin do?
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Forms sheath over most of body-skin can move independently to underlying muscles
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What are the first muscles to be used?
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Muscles on head-used for nursing
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Why is dermal musculature well developed?
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Important in social behavior.
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How does the skeleton of a mammal differ from a reptile?
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Simpler and more completely ossified ; greater fusion of bones, axial skeleton more flexible; pattern of bone growth
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What is different about bone growth in reptiles compared to mammals?
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Their bone growth continues throughout their lifetime, occurs at ends of limbs, and this limits the definition of joint- in most mammals, growth is limited n early part of life; then stops
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What is one of the keys of success for mammals?
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Specialized teeth
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What type of dentention do most mammals have? What does this mean?
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Herodont- teeth differ in structure and function
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What is the function of canines and incisors?
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Used to gather or kill food
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What is the function of cheek teeth?
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Used to grind or slice food
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What are the two sets of teeth mammals have? Which type of teeth are included in these sets?
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Deciduous dentition- incisors, canines and premolars
Permanent dentition- above plus molars |
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What is the order of teeth dental formula?
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ICPM- incisors, canines, premolars and molars
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What is the dental formula for an African hunting dog?
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3 1 4 2
3 1 4 3 |
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Why are mammals much less diverse than invertebrates?
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Prob. Due to far greater individual size, high energy requirements of endothermy and inability to exploit many restricted ecological niches.
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