Foods and FeedingMammals that depend on plants need a much more complicated, much longer digestive tract than those who depend on animal products. Omnivores are in between. Few specialized mammals who have their own adaptations to their diet.Mammalian Structure and Function: ReproductionI. Characteristics of living mammals (*diagnostic)II. Some comparisons of mammalian infraclassesIII. Basic anatomy and physiologyDuplexBipartiteBicornuateSimplexIV. Interesting mammalian reproductive strategiesMarsupial-Placental DichotomyI. Why do marsupials and placentals differ in their mode of reproduction?II. Are marsupials inferior? Not found in as many places across the globe. Protected in Australia where there are diversified and where there are very few eutherians.Foods and FeedingA. Anatomy of the digestive system (Fig 7.2) 1. Mouth (teeth tongue), intestines, cecum2. How digestive system has evolved in relation to dietB. Modes of foraging 1. Insectivorya. Aerial: feeding on insects as the insects are flying around in the air. Mammal also flies. Ex: batb. Terrestrial: on ground. Ex: shrews and moles, monotremes, platypus, some carnivores, some primates.c. Myrmecophagy (ant-eating)2. Carnivory: eating other animalsa. Terrestrial ex: tiger eating deerb. Aquatic ex: seals, sealions, whales, dolphins eating fish or other mammalsc. Sanguinivory (blood feeding): very specialized, only occurs with vampire bats3. Herbivory a. Ruminants and Hind gut fermenters: cellulose can’t be digested by mammals themselves. Portions of digestive tracts have colonies of microbes in them to help break down cellulose and free nutrients for mammal. Two different approaches to the same problem.A. Ruminant has more compartments in stomach, different stomach structures. Ruminant, chunks of food get sorted. Regurgitate large chunks to rechew and reswallow them. Small chunks able to pass through. A lot more processing in ruminants. Microbes sit in cecum, fermenting. B. Hind gut fermenter has secum in “hind” half of tract. When food is limiting but at reasonably high quality, hind gut fermenters do better. Plentiful low quality food better for ruminants (cardboard boxes for cows). b. Granivory: eating grains which are seeds. Not high in cellulose but in starch and carbohydratesc. Folivory: eating leaves. More nutritious in early growing phases. Very specialized way of eating, need microbes in gut to digest cellulosed. Frugivory: eating fruit. Low in cellulose high in carbse. Nectivory: nectar, usually have to supplement with pollen for protein. Ex: marsupials. f. Gumivory: eating sap from trees, not specialized. Use teeth to make wounds in trees then drink sapg. Mycophagy: specializing on fungi.4. Filter feeding: plankton. Ex: whales and dolphins 5. Omnivory: eat everything. Ex: humansC. Anatomical specializations associated with different modes of foraging Mode of foraging Teeth Tongue Stomach Intestines Cecum Insectivory Numerous, spiky, incisors enlarged and procumbentExample: mole, shrew -- Simple, one chamber Short Mostly lacking, bc. don’t eat plant material Myrmecophagy Absent or reduced in numbers, peg-likeExample: tamandua anteater Extremely long (Fig 7.3) use tongue to collect food, covered with large salivary glands and sticky mucusOften roughened, need to break down chitin from insect bodies. Smash up with inside of stomach by teeth like structures made of keratin. Muscular. Chew food in jagged, rough inner layer of stomach instead of with teeth.Short Small or lacking Terrestrial carnivory Sharp incisors; long, conical canines; often carnassial cheek teeth; may have crushing molars. Adapted for capturing and stabling, slicing. Example: dog -- Simple Short Small Aquatic carnivory Homodont, spiky, numerous. Don’t process food, no chewing, just cage fishExample: common dolphin -- Simple or multichambered (cetaceans) Variable Small Sanguinivory Very specialized, very sharp upper incisors; reduced cheek teeth. Go after large animals. Shallow cut so wound keeps bleeding.Example: vampire bat Grooved like a straw,anticoagulant in salivary gland. Tubular, highly extensible, lots of vasculature to take water out of blood, reduce it to only nutrientsLong Lacking? 1Herbivory (except nectivores) Incisors robust or absent; canines reduced or absent; diastema; cheek teethenlarged with complex occlusal surfaces. Often has open rooted incisorsor cheek teeth.Example: beaver -- Simple (hindgut fermenters) or multichambered (ruminants) Long Large to house colonies of bacteria Filter feeding None (baleen) just keratin structuresExample: humpback whale -- Multichambered -- -- Omnivory Sharp incisors and canines; flat cheek teeth with rounded cusps. Generalist characteristics Example: bear -- Simple Long Small Mammals that depend on plants need a much more complicated, much longer digestive tract than those who depend on animalproducts. Omnivores are in between. Few specialized mammals who have their own adaptations to their diet. Mammalian Structure and Function: ReproductionI. Characteristics of living mammals (*diagnostic) A. All mammals are dioescious; sexes are separate and a given individual has the sexorgans and secondary sexual characteristics of only one gender.B. Glands a. Mammary glands* two basic types in eutherians Monotremes very simple, no nipple, more like a sweatgland Cows, sheep, horses, milk doesn’t stay in glandular tissue, sits incistern. Nipple, or teat, has single opening.e.g., cows, sheep, horses e.g., primates mammary tissueBmammary tissue (=lobules) inactive active Milk collects in cistern, not in glandular tissue. Can store more milkcollecting ducts milk sits in glandular tissue until infant attaches and starts sucking it out. teat has one opening only. Sphincter duct. nipple has multiple openingsb. Complex placenta* (except monotremes, most marsupials) Structure varies in marsupials, eutherians all have similar structures.  Armadillo : identical quadruplets. Each has own amnion, carrion surrounds all. If they came from different eggs, they would have their own set of placental membranes. Important biomedical models Human : blood vessels run through umbilical cord then branch through structure. II. Some comparisons of mammalian infraclassesA. Similarities in reproduction between mammalian infraclasses:1. Internal fertilization 2. Nourish young with milk from mammary glands B. Differences: mode of reproductionPrototheria