Lecture 8 RH - Mammals Flashcards
What organ is common to all mammals?
Mammary glands
What are the general characteristics of mammals?
Hair as body covering
Integument with sweat, scent, sebaceous, and mammary glands
Structure of skull and skeleton
Diphyodont teeth - milk or deciduous teeth replaced by permanent teeth
Heterodont teeth - Different types
Lower jaw is made up of single dentary bone
Secondary palate that separates nasal cavity from buccal cavity
Brain highly developed with large cerebral cortex
4 chambered heart
Left aorta
Non-nucleated biconcave red blood cells
Diaphragm divides body into thorax and abdomen
What is lower jaw made up of in mammals?
Single dentary bone
What is the function of the secondary palate?
Separates nasal cavity from buccal cavity
What does the brain of mammals look like?
Highly developed with large cerebral cortex
Do mammals have a cloaca?
Only monotremes. The rest of mammals have separate anal and urinary openings
Are mammals mono or dioecious?
Dioecious
What is the copulatory organ of mammals?
Penis
Is fertilization internal in all mammals?
Yes
What are the foetal membranes in mammals?
Amnion
Chorion
Allantois
What are the 3 major groups of amniotes?
Anapsid: Solid skull (turtles and ancestors)
Synapsid: Pair of openings in roof of skull for jaw muscle attachments (led to mammals)
Diapsid: 2 pairs of openings in skull roof (dinosaurs, reptiles, birds)
What are monotremes?
Mammals that lay eggs; eg platypus
Which mammals have only survived in Australia?
Marsupials and monotremes have only survived in Australia
What is hair composed of?
keratin
What other structures are composed of the same component as hair?
Nails, horns, claws, hooves, and feathers
Do mammals moult?
Periodically 2 coats - summer and winter coats
What is the purpose of moulting?
Camouflage
Sensory hairs
Spiny armour in porcupines, echidnas
What are true horns of sheep and cattle made of?
Sheaths of keratinized epidermis
What are antlers of deer made of?
Solid bone branched
How do antlers develop?
Beneath vascular velvet skin and they decline after rutting season as hormones decline
What is rhino horn made of?
Hairlike keratinized filaments and is used for chinese medicine driving it to near extinction
What is interesting about antelope horns?
They shed annually
What is rhino horn used for?
Chinese medicine
As an aphrodisiac
What are the types of sweat glands?
Eccrine glands produce sweat to cool skin
Apocrine glands open to hair follicle. Milky fluids - activity is correlated to reproductive cycle
What are scent glands used for?
Social activity such as marking territory
Mating scents to attract opposite sex
What is the function of sebaceous glands?
Produce sebum which keep skin pliable and glossy
Do monotremes have nipples?
No
What happens to metabolism in smaller animals compared to larger animals?
Metabolic rate/gram of body weight is a lot higher in smaller animals
What is the cost of migration?
Very energetically expensive
What is an example of a mammal that migrates?
Caribou migrate from Canada and Alaska and vice versa from Winter feeding grounds to summer breeding grounds in Canada