Mammals 1 Flashcards
What is the sebaceous gland? What does it do?
A gland in the dermis that secretes protective oil around the hair follicle
secrtes an oily mixture (sebum) into hair follicles to keep hair and skin soft and pliable
What is hair composed of?
Keratin
What kinds of features are composed of the same protein as hair?
nails, claws, hooves, whale baleen, and feathers are composed of keratin
The fur coat is also known as what?
Pelage
What are the two hair types that make up the Pelage?
underhair - dense and soft for insulation
guardhair - coarse and longer for protection and colouration
Do all mammals have hair?
Hair is a characteristic of mammals but some have secondarily lost their hair.
ex. whales, naked mole rats
What are 2 purposes for the modifications of some hairs?
defense (quills) or sensory funtions (whiskers)
What are three main characteristics of mammals?
Hairy, Milk-producing, Endothermic vertebrates
What are milk glands?
modified sweat glands
What are vibrissae?
modified hairs for sensing - Whiskers
What kind of hair is human hair?
Bristles similar to lion and horse manes
What is a Rhino horn if it is not a true horn?
Dense, modified hair
What is the process of periodically replacing hair called?
molting
What are sweat glands?
Produce sweat for evaporative cooling and occur over the majority of the body in most mammals
How often does molting occur and what kind of purpose?
Can occur once, twice, or three times a year and switches between summer and winter coats etc.
What are 4 kinds of sweat glands/modified sweat glands?
Sweat glands
Scent glands (pheromones, skunks)
Milk glands
Ear wax (possibly)
What are three purposes for scent glands?
Territorial marking
Attract mates (pheromones - can be inter or intra)
Defense
What is the predominant sense in mammals? What is the exception?
Olfaction
Exception is primates where vision is most important because of an adaptation to arboreal lifestyle and perception of colour for food choice (fruit colour)
What is flemen?
Stallions block nostrils to focus exclusively on pheromone identification
Related to Jacobson’s organ between smell and taste
When do stallions use flemen?
In the presence of mares to detect pheromones
What are 3 types of mammae and where are they on the mammal? Give an example of a mammal that exhibits each type.
Inguinal in the pelvic region - hoofed mammals, whales and porpoises
Pectoral in the forleg/arm region of chest - elephants, bats, primates, manatees, sloths
Both pectoral + inguinal - canids, felines, pigs
What are 6 characteristics of mammals?
1) Hair
2) Integumentary glands (sweat, sebaceous)
3) Endothermic and homeothermic
4) Mandible (lower jaw) = single bone
5) 3 inner ear bones (not one)
6) Diaphragm (negative pressure breathing)
What are 5 characteristics of mammary glands?
- All female mammals
- Form along “milk lines” from axilla to groin
- Number varies among and within species (2-27)
- Position varies among species
- Connection between number of teats and how many young
What is endothermy
regulation of body temp internally and generating heat by muscle shivering, fat burning, altering blood flow, panting, sweating
What is Homeothermy?
maintaining a constant body temp and it is usually well above ambient temperature
The ability to keep temperature relatively even.
What is the diaphragm?
An organ that separates the body cavity and expands and contracts lungs with negative pressure breathing
What are the characteristics of most mammalian teeth?
Heterodont - different specialized teeth types
Diphyodont - 2 sets of teeth (deciduous - baby and permanent)
What are the elephant and narwhale tusks derived from?
upper incisor teeth
What are walrus tusks derived from?
upper canine teeth
Why do male horses have canine teeth?
Defense and male-male combat
However, male-male combat is rare due to the waste of energy, time and risk of infection
Teeth are important to natural selection because…?
Death can happen if teeth rot and an animal starves
What is characteristic of herbivore teeth?
typically lacking canines and premolars and molars are often flat for crushing and grinding plant material
What is the diastema?
the gap between teeth often seen in herbivores
What are the two types of herbivores?
Gnawers (beavers) and Grazer/Browsers (deer)
What are the incisors for?
snipping and biting
What are the canines for?
piercing and holding
What are the premolars for?
shearing and slicing (bicuspid, deciduous, 2 roots)
- can be modified for chewing/masticating
What are the molars for?
crushing/grinding (3-5 cusps, permanent, 2 or more roots)
What are carnassial teeth?
adapted for slicing meat in carnivor dentition
What is different about the teeth of a beaver?
The incisors and cheek teeth grow continuously throughout life
What kind of teeth do insectivores have?
They do not have teeth -edentate
What are a few examples of insectivores?
ant-eater, shrews, moles, most bats
What is the principle feeding tool of insectivores?
the tongue
What is a frugivore? What kind of dentition do they have?
Fruit-eating and have carnivorous looking teeth for crushing hard fruits
- fruit bats
What are the feeding habits of carnivores?
feed on herbivourous creatures
What is the difference between gnawer and browser/grazer feeding habits? Why is this significant?
gnawers eat trees/barks (cellulose?)
browsers eat more of plant/tree foliage material
grazers eat more herbs and forbs lower on the ground
Significant for niche diversification and resource partitioning
What kind of dentition to omnivores have?
Between carnivore and herbivore
What are a few examples of animals with ruminants?
Goats, buffalo, giraffes, deer, bison, antelopes
What is the difference between carnivore and herbivore digestion systems?
Carnivore is shorter with a very small cecum
Herbivore is has a large, well-developed cecum for aiding in the digestion of plant material and cellulose and has a longer digestion system of intestines
What is a Rumen?
an organ similar to a cecum that is a “sorting ally” in the stomach of a ruminant (cow) that is a digestion aid in optimum nutrient extraction
How does the rumen work?
The animal will chew the food and it will go to the rumen where a chemical digestion takes place to release nutrients. The chewed and partially digested food is then regurgitated and chewed more to expose more surface are to digestive enzymes. More mechanical digestion opens up to more chemical.
What is the path of food through a ruminant?
Esophagus, rumen, esophagus, mouth, reticulum, omasum, abomasum, intestines
Why do lagomorphs, rodents, shrews and some marsupials eat their own feces?
because evolution isn’t perfect and the nutrients are not fully extracted the first time through the digestive system. This is partly because the caecum is in the “wrong” place to extract all the nutrients
What is coprophagy?
feeding on feces
What are cecotropes and where are they produced?
cecotropes are 1st cycle fecal pellets rich in B vitamins and minerals produced in the caecum by bacteria
What two kinds of feces are produced in animals that take part in coprophagy?
1) hard, round feces that are not eaten
2) moist fecal pellets (cecotropes) that are eaten directly from the anus or stored for later use
What are 2 behaviors related to storing cecotropes?
1) separating 1st from 2nd cycle pellets in different piles
2) cache the cecotropes in underground chambers for later ingestion (storing for winter)
