Mammals – Part III VERTEBRATE ZOOLOGY (VZ Lecture31 – Spring 2012 Althoff - reference PJH Chapters 18-20) Bill Horn

Basics ___________ glands a) present in all mammals b) mucilaginous material present in anteaters & pangolins--sticky Various ____________ patterns for cutting (incisors), shearing (carnassials), grinding (i.e., occlusal surfaces of molars & premolars) Stomachs: simple & complex

Collared anteater -- “toothless”

Salivary Glands…not just for “digestion” Rich mixture of compounds that directly affect individual survival and competitive success: 1) provides access to nutrients 2) maintains oral epithelial tissues 3) maintains dental tissues 4) maintains gastric tissues 5) maintains nervous tissues (taste buds) 6) in rodents, recently discovered pheromone (think communication) 7) transfer airborne molecules to vomeronasal organ 8) used for evaporative wetting (fur-wetting) 9) provides some defense against disease 10) transmission of disease (ex. rabies, hantavirus, brucellosis, etc.)

Dentition: Molariform Occlusal Surfaces Considerable variety across the class Mammalia…. Even within certain orders considerable variety such as found in the order __________ (mice, rats, beaver, muskrat, porcupine, etc.) mole-rat voles, lemmings old world porcupines chinchilla cuspid-pattern: squirrel species “folded” enamel: some murid (rat) species

Dentition…some other specializations _________: well developed in many carnivores ___________: in many carnivores (especially well developed in cat (Felidae) and dog (Canidae) family….. Last upper premolar & first lower molar  results in shearing action (“scissor”-like) ________________: many rodents. Important for sniping vegetation

Stomachs Simple: most species of mammals have sac-like compartment Complex: subdivided. a) ruminant artiodactyls b) cetaceans (whales & dolphins) c) sirenians (mantees & sea cows)

Simple Stomachs 1 major “chamber” for initial processing (i.e., stomach) in most mammals a) no cecum (insectivores, vampire bats) b) “modest” cecum (carnivores) c) elongated cecum (rabbits & others) 3 major “chambers” for processing (in stomach) in ruminants plus a) cecum “in-line” with entire tract b) small intestine

Koala

Complex Stomachs: RUMINANTS Artiodactyls such as bovidae (bison, bighorn sheep, mt.goats), antilocapridae (pronghorn), and cervidae (deer, elk, moose, caribou) in North America All are exclusively herbivores

Ruminants...continued Digestion aided by micro-organisms that inhabit stomach...referred to as _____________________ which are small, various bacteria & protozoa Most lack enzyme cellulase (thus can’t handle cellulose) Four-chambered stomach

Ruminants: 4-chambered stomach in the esophagus   rumen  reticulum  omasum  abomasum  out the small intestine

4-chambered stomach

Rumen First chamber of stomach Storage chamber during feeding During rest, regurgitates the food to “chew cud” Also, it is a ________________ vat: carbon dioxide (CO 2 ) & methane (CH 4 ) produced 1

Rumen...continued Fermentation brought about by presence of microflora Microflora responsible for breakdownof cellulose a) composition varies ___________________ b) cattle more “advanced” than deer…(i.e., more efficient at processing veg, particularlygrasses) 1

Note: If ruminants go very long without eating or eating proper diet, quantity of “active” microrganisms can decrease to point that not enough of them can be “supported”....when this happens appetite and rumen activity can stop resulting in animal starving even in presence of newly provided/available food.

Products of Rumen Activity Gases: CO 2 & methane _________________________ (VFAs) --the most important product of fermentation because they readily absorbed from the rumen and are a major energy source ___________ (typical diet “incoming” is 6-7% protein…”squeezes” more out of food)

Note: In monogastric animals, most energy (from carbohydrates) is absorbed from the small intestine in the form of glucose...in ruminants this takes place with VFAs in the rumen (with rumen wall absorbing some) and subsequent chambers

Reticulum Second chamber of stomach Digestion, cellulose breakdown continue Squeezes out water in bacteria, recycles it some…. 2

Omasum Third chamber of stomach Pummels contents once more Essentially, no digestion taking place here 3

Abomasum Fourth chamber of stomach “True” stomach Gastro-digestion occurs as stomach acids secreted to further breakdown contents...in other words, same “actions” that take place in monogastric systems 4

Summary Points/Comments _________ digestion takes place in rumen (1st chamber) Some digestion takes place past stomach complex...i.e., in the large & small intestines Nutrients ___________________ gastrointestinal tract

Advantages of Rumen Digestion Protein synthesis carried out by inorganic substances through ____________ activity Allows existence on ______ protein diet because proteins produced (most plant parts are low in protein (<12%, usually even lower) content relative to carnivore/insectivore diets (protein content ~15-50%)

Disadvantages of Rumination Carry “_______” food Fermentation is _______ process mouth-to-anus times: a) horses hours b) cows hours Must eat “_________”....going days without food devastating

Basic Diet Categories Insectivorous Carnivorous Omnivorous Herbivorous a) foregut fermenters b) hindgut fermenters c) gnawing mammals (do not produce cellulase)

Specializations among Herbivores (besides those consuming leaves & stems) Granivorous—fruits, nuts, and seeds (Heteromyids: all cache seeds) Folviorous—leaf eating Frugivorous—fruit eating Nectarivorous—nectar eating (some bats & honey possum) Gumivorous— gums, saps, & resins Mycophagous--fungus

Food Hoarding Hoarding = caching LARDER HOARDING—all food stored concentrated at one site SCATTER HORADING—one food item per site Common among mammals: (especially rodents) a) larder hoarding most common b) storage usually >10 days

Hoarding/Caching Sites Burrow Cavity Foliage Ground Litter Nest Snow Soil Tree trunks/ branches Water

Make ______ while the sun shines…. PIKA Lagomorph (rabbits/hares) “cuts, gathers, dries, re-gathers, and stores “hay” for the winter”