Zoology Final d Flashcards
common mammal characteristics
- mammary glands
- sweat glands
- hair
- 3 middle ear bones
- neocortex in the brain
- diaphragm
skin
- hair follicles located in dermis of skin
- as new cells are produced they are carried away from their source of nourishment and die, turning into keratin
two kinds of hair
- underhair
- guard hair
underhair
- for insulation
- so dense in aquatic mammals that i keeps them from getting wet
guard hair
for protection and coloration
skin glands
- sebaceous glands that produce sebum
- scent glands used for communication; located on head, penis, anal region, back of head, legs, armpits
two types of sweat glands
- eccrine glands
- apocrine glands
eccrine glands
for evaporative cooling
apocrine glands
- associated with reproductive cycle
- types: mammary gland
mammary gland
occur on all female mammals and in rudimentary form on males
horns and antlers
- horns have core of bone and are permanent
- antlers develo in spring beneath velvet and are shed each year
What animal has been pushed to brink of extinction by demand for its horns?
white rhinoceros from Asia Africa
teeth
- sets mammals apart and reveals life habits
- mammals have heterodont (different) dentition, where reptiles have homodont (same) dentition
dentition
teeth
animals with homodont dentition
american crocodile
animals with heterodont dentition
fox
tiger
what are different types of teeth in mammals
- incisors
- canines
- premolars
- molars
incisors
used to nip, seize food
canines
used to kill, stab prey
premolars
used for slicing and crushing
molars
used for crushing
diphyodont dentition
having two sets of teeth:
- temporary set (baby teeth)
- permanent set
deciduous teeth are what?
- baby teeth
- milk teeth
different feeding types in mammals
- insectivores
- carnivores
- omnivores
- herbivores
- variations have occurred such as filter feeding in whales
characteristics of insectivores
- short intestine, no cecum
- little fibrous vegetable matter that requires prolonged fermentation
characteristics of nonruminant herbivores
- elephants, rodents, horses rabbits
- cecum serves as fermentation chamber harboring microorganisms that can break chemical bonds of cellulose
- simple stomach, large cecum
characteristics of ruminant herbivores
- cattle, bison, goats, antelopes
- four-chambered stomach with large rumen
- cud formed in rumen returned to mouth for chewing, then back to rumen
- relatively long intestines
rumen
chamber to help in digesting cellulose
what are the three different types of herbivores?
- nonruminant herbivores
- ruminant herbivores
- herbivores that exhibit coprophagy
herbivores that exhibit coprophagy
- hares, rabbits, some rodents
- eat own feces to give food second pass through cecum
characteristics of carnivores
- short intestine and colon, small cecum
- no need to feed continuously as herbivores do
- get enough our of what we they do eat
characteristics of omnivores
- small or no cecum
- relatively long intestine
respiration in mammal
possess diaphragm for creating negative pressure to suck air into lungs
pinnae
- adaptation of head
- external ears
- used to catch sound, thermoregulation
ears in mammals
- more complex inner ear
- 3 middle ear bones: malleus, incus and stapes
hearing in mammals
- very well-developed especially in bats
- echolocation enables bats to navigate in total darkness
- toothed whale and dolphins use echolocation too
earliest synapsids reptiles
- pelycosaurs
- neural spines of vertebrae supported large sail-like structure, possibly for thermoregulation
- teeth show beginnings of heterdont dentition
synapsids
refers to shape of skull, holes in head for attachment of jaw muscles
After synapsids, came therapsids….
had efficient erect gait with upright limbs positioned beneath the body
after therapsids, came cynodants….
- high metabolic rate
- increased jaw musculature
- mammal-like, heterodont dentition
skull characteristics
secondary cony palate enabling animal to suckle and breathe at same time, also to eat and breathe at same time
- separates nasal cavity from oral cavity
what is the most primitive group of mammals?
- prototherians
- internal fertilization, egg-laying mammals
- duck-billed platypus and spiny anteater
- other names: echidna and monotherians
what is the second major group of mammals?
- metatherians
- young nourished via primitive placenta in a pouch called marsupium
types of marsupials
- kangaroo
- koala
- tasmanian devil
- wombat
- opossum
what is the most advanced major group of mammals?
- eutherians
- true placental mammals
types of eutherians
- dolphins
- humans
- cows
endangered mammals
reasons for endangerment:
- habitat loss
- poaching
- pesticides and other toxins
- global warming
