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42 Cards in this Set
- Front
- Back
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What characteristics are unique to mammals, and separates them from all other chordates?
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mammary glands
sweat glands hair 3 middle ear bones neocortex in the brain |
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Where are hair follicles located, and how is hair produced from them?
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follicle located in DERMIS of skin; as new cells are produced they are carried away from their source of nourishment and die, turning into KERATIN
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What are the two kinds of hair?
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-underhair for insulation
-underhair is so dense in aquatic mammals that it keeps them from getting wet (it’s waterproof)! -guard hair for protection and coloration |
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do whales have hair?
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yes, just a few bristles for sensory
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What glands produce a fatty substance to keep mammalian skin and hair pliable, and what is the substance produced?
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sebaceous glands produce sebum
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What mammalian skin glands are used for communication, and where are they located?
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-scent glands (depending on species, located on head, penis, anal region, back of head, legs, or armpits)
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What are the two kinds of sweat glands associated with the skin of mammals?
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-ECCRINE glands for evaporative cooling
-APOCRINE glands associated with reproductive cycle (these are scent gland located in armpits and genitals) |
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What are mammary glands?
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-probably modified apocrine glands
-occur on all female mammals and in a rudimentary form on all male mammals |
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What is the difference between horns and antlers?
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-horns have a core of living bone and are permanent
-antlers develop in spring beneath velvet and are shed each year when testosterone levels decrease (after mating). They grow in each year in response to an increase in daylight. |
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What animal has been pushed to the brink of extinction by demand for its horn, which is used for medicinal treatments in Traditional Chinese Medicine and dagger handles in the Middle East?
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white rhinoceros from Asia and Africa
(in the past 25 years interest in traditional Chinese medicine has increased, which has increased poaching) |
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What, more than any other single characteristic, reveals the life habits of a mammal?
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teeth
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How does the dentition of mammals differ from that of reptiles?
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-mammals have HETERODONT dentition (different kinds of teeth do different things), whereas reptiles have HOMODONT dentition (teeth are all the same)(
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teeth for nipping and seizing prey?
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incisors
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teeth for killing /stabbing prey?
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canines
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teeth for slicing and crushing
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premolars
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teeth for crushing?
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molars
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term for the mammal condition:Two sets of teeth: temporary "baby teeth” (a.k.a. “milk teeth), and permanent teeth
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diphyodont dentition
*“Baby teeth” or “milk teeth” are deciduous & In some mammals, molars are not preceded by baby teeth |
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great whales feeding specialization?
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filter feeders
*use BALEEN |
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How would you describe the digestive system of an insectivore?
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-short intestine, no cecum
-little fibrous vegetable matter that requires prolonged fermentation |
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fermentation chamber for breakdown of cellulose, by bacteria?
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CECUM
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How would you describe the digestive system of nonruminant herbivores such as horses, rabbits, elephants, and many rodents?
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-cecum serves as fermentation chamber harboring microorganisms that can break chemical bonds of cellulose (since no vertebrates can synthesize enzymes that can break down this substance)
-simple stomach, large cecum *-need large amounts of food - up to 400 pounds per day in elephants |
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-hares, rabbits and some rodent herbivores exhibit ________.
Eat own feces to give food a second pass through cecum. |
coprophagy
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How would you describe the digestive system of ruminant herbivores such as cattle, bison, goats, antelopes, etc?
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-four-chambered stomach with large rumen (for microbial digestion)
-cud formed in rumen returned to mouth for chewing, then back to rumen -relatively long intestines *Fyi: these animals tend to live in ecosystems with good quality food but not much of it (like tundras or deserts), It’s the most efficient way to use food and they get a lot out of a little. |
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How would you describe the digestive system of a carnivore?
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-short intestine and colon, small cecum (no need for one)
-no need to feed continuously as herbivores do (get more out of it because meat is easier to digest) |
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How does the respiratory system of a mammal differ from that of all other vertebrates?
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-only mammals possess a DIAPHRAGM for creating negative pressure to suck air into the lungs
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What adaptation of the head is characteristic of mammals compared to other land vertebrates?
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PINNAE...external ears
-used to catch sound |
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How does the internal anatomy of the mammalian ear compare to that of other land vertebrates?
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-more complex; 3 middle ear bones instead of 1 (the columella) in birds, reptiles and amphibians
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How well-developed is hearing in mammals?
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-very well developed, especially among bats
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What enables bats to navigate in total darkness
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Ecolocation!
*can hear sound frequencies of 100,000 Hz (cycles per second), compared to 20,000 Hz in humans |
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What is the status of bats worldwide?
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-many species are threatened due to habitat loss, human mythology and ignorance (Bats won’t get tangled in your hair, but they may carry rabies…)
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What is the most primitive group of mammals?
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PROTOTHERIANS: internal fertilization, egg-laying mammals; includes the duck-billed platypus and the spiny anteater (also called the echidna)
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What is the second major group of mammals?
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METATHERIANS (marsupials) - young nourished via a primitive placenta in a pouch called a MARSUPIUM
*Babies are very tiny at birth, they are just beginning to form functional organs. Most of the development takes place in the pouch |
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What is the most advanced major group of mammals?
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EUTHERIANS - true placental mammals
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What were the earliest synapsid (mammal-like) reptiles?
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PELYCOSAURS
-neural spines of vertebrae supported large sail-like structure, possibly for thermoregulation -teeth show beginnings of heterodont (specialized) dentition, as opposed to homodont dentition of other reptiles |
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What synapsid group survived beyond the Paleozoic?
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THERASPIDS; they had an efficient erect gait with upright limbs positioned beneath the body
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a group of animals that includes mammals and everything more closely related to mammals than to other living amniotes
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SYNAPSIDS
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What therapsid group survived to the Mesozoic era?
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CYNODONTS
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What mammalian features did CYNODONTS possess?
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-high metabolic rate
-increased jaw musculature -mammal-like, heterodont dentition |
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What very important skull characteristic of modern mammals was first found in the cynodonts?
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SECONDARY BONY PALATE, enabling animal to suckle and breathe at the same time, also to eat and breathe at the same time (completely separates nasal cavity from mouth cavity)
-FACIAL MUSCLES- first enable suckling, but also allows facial expressions to varying degrees |
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Cynodonts are extinct. What are just a few of the world's mammals that currently face extinction?
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-Black-footed Ferret - no wild population known
-Javan Rhino - fewer than 75 survive -Yangtze River Dolphin - probably fewer than 100 -Vancouver Island Marmot - probably fewer than 100 -Arabian Oryx - about 500 in wild -Giant Panda - about 1000 - |
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What are some reasons why so many mammals are threatened or endangered worldwide?
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-habitat loss
-poaching -pesticides and other industrial toxins -global warming which could shift climate patterns; especially critical for highly specialized mammals that cannot tolerate changes in their habitat |
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reptiles, birds and mammals form what monophyletic group?
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AMNIOTES
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