Herbert Flashcards
Four traits that distinguish mammals from reptiles?
Homeothermic
Suckling of young
Body hair
Muscular diaphragm
What is the difference between prototheria, metatheria, and eutheria?
Prototheria- egg layers (monotremes)
Metatheria- embryonic young (marsupials)
Eutheria- birth more developed young
What are the origins of marsupials and monotremes?
Breaking off from Antarctica 35-40 million years ago
What are the origins of Australian eutherians?
Island hopping 5-6 million years ago
What are the most easily recognisable differences between ameridelphia and australidelphia?
Structure of the tarsal bones
Also blood proteins, DNA and sperm morphology
What are the four orders of marsupials?
Dasyuromorphia
Peramelemorphia
Diprotodontia
Notoryctemorphia
What is the name of the opposable 1st digit on the hind foot present in some marsupials?
Hallux
Define polyprotodont
Multiple pairs of lower incisors
Define diprotodontia
One pair of incisors in the lower jaw.
Define syndactyly
Normal occurrence of having two or more fused digits in a mammal species.
Between what two digits is syndactyly most common?
II and III
What is the dentition of dasyuromorphids?
Polyprotodont
Would a spotted quoll have one or more digits fused together naturally?
No, it is a dasyurid, they do not have any syndactyly
Bandicoots have three pairs of equal sized lower incisors.
Yes they are of the order peramelemorphia which are polyprotodonts
Syndactyly is a defining aspect of peramelemorphia
True/ False
True
What does the order notoryctemorphia include?
Marsupial moles
All diprotodonts have one pair of lower incisors
True or false?
True
What order do koalas belong to?
Diprotodontia
All diprotodonts have syndactyly
True/ False
True
What is the significance of the path of the ureters in marsupials?
Prevents the fusion of the vagina into a single structure
Define polyoesteus
Multiple cycles in breeding season
How is ovarian activity modulated in marsupials?
By lactation
Describe the placenta of bandicoots koalas and wombats
Chorioallantoic
Structure and function of the pouch?
Structure
Invagination of skin of ventral abdomen through a gap in cutaneous muscles, interior skin is hairless, coated by a brown secretion
Function
High humidity and stable temperature for growing young
Mammary glands with long nipples to suckle young
What is embryonic diapause?
A female mates while a young is in her pouch. The conceptus is suspended until the first young has finished suckling.
How does embryonic diapause work?
Corpus luteum develops and is then inhibited by suckling stimulus
Solitary marsupials are usually…
Small nocturnal carnivores/omnivores
Exceptions include brushtails and koalas
What is sexual size dimorphism?
Significant difference in size between the sexes within a species
How do marsupials cope with cold conditions?
1 increase metabolic rate
2 huddling in groups
3 torpor (pseudo hibernation)
How do marsupials cope with heat?
Panting, sweating, licking paws
How is a marsupial heart different to a eutherians heart?
30% heavier Resting heart rate = lower Max heart rate = similar Max stroke volume is larger CO = greater Resting respiratory rate = lower Tidal volume = greater
What is the difference in resting body temperature between marsupials and eutherians?
2-3 degrees lower
What is a volplane?
Fold of skin between elbow/digit 1 forelimb and stifle/digit 5 of hindlimb that allows for gliding
Regarding the hind limb of marsupials what could be regarded as insufficiently developed?
Patella
What is the top speed of a kangaroo?
70 km/he
Outline the gastrointestinal tract of a carnivorous marsupial.
Very simple
No caecum
Small intestine and large intestine short with similar diameter.
What is the difference between the gastrointestinal tracts of omnivores and carnivores?
Salivary glands are larger Small intestine is longer Large intestine more developed for fermentation Caecum = generally large Colon = longer and greater diameter
What is the dentition of an omnivorous marsupial?
Polyprotodont
What is the diastema?
Space where the premolars are present in the mouth of diprotodonts
Outline the characteristics of a foregut fermenters gastrointestinal tract.
Stomach expanded and sacculated Caudal "hindstomach" = glandular Cranial forestomach = fermentation Small intestine = long Colon and caecum well developed
What species are foregut fermenters
Kangaroos and wallabies
Outline the characteristics of a Hindgut fermenters gastrointestinal tract
Simple stomach
Enlarged caecum and/or colon
What is the cardio gastric gland patch?
Invaginated area of mucosa near the cardia
What are some problems for Hindgut fermenters?
Less opportunity to absorb microbial amino acids and b vitamins
Issues with antibiotics
What is caecotrophy?
Ingestion of caecal faeces for nutritional purposes.
