Download MAMMALOGY AS A SCIENCE

VERTEBRATE ZOOLOGY
(VZ Lecture31 – Spring 2012 Althoff - reference PJH Chapters 18-20)
Mammals – Part III
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
3
1
2
4
1 Rumen
•
First chamber of stomach
• Storage chamber during feeding
• During rest, regurgitates the food to “chew cud”
• Also, it is a ________________ vat: carbon
dioxide (CO2) & methane (CH4) produced
1 Rumen...continued
•
Fermentation brought about by
presence of microflora
• Microflora responsible for breakdown of cellulose
a) composition varies ___________________
b) cattle more “advanced” than deer…(i.e.,
more efficient at processing veg,
particularly grasses)
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: CO2 & 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
2 Reticulum
• Second chamber of stomach
• Digestion, cellulose
breakdown continue
• Squeezes out water in bacteria,
recycles it some….
3 Omasum
• Third chamber of stomach
• Pummels contents once more
• Essentially, no digestion taking place here
4 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
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-- 8 - 24 hours
b) cows-- 70-100 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”