Small Furries Flashcards
‘Small furries’ come under which order in taxonomy? What is the characteristic of this order?
Rodentia
- Constantly growing incisor teeth
What is the smallest and largest species in the Rodentia order?
Smallest = Pygmy jerboa Largest = Capybara
Give 3 examples of Myomorpha
Rat
Mouse
Gerbil
Hamster
Give 3 examples of Hystrictomorpha
Guinea pig
Chinchilla
Degu
Compare the dental formulas of myomorpha and hystricomorpha
Myo = I 1/1, C 0/0, PM 0/0, M 3/3 = 16 total Hyst = I 1/1, C 0/0, PM 1/1, M 3/3 = 20 total
Describe the incisors of Rodentia
Open rooted, constantly growing (aradacular, elodont)
Lower to upper length ratio is 3:1
Give definitions for the following terms:
- Aradacular
- Elodont
- Anelodont
Aradacular = open rooted Elodont = continually growing Anelodont = Grow for a short period of time and then stop
How does an incisor chisel shape form?
Hard enamel on rostral side.
Softer dentine wears more quickly resulting in chisel shape
Compare molar growth in myomorpha and hystricomorpha
Myo = Anelodont - grow for a short period of time and then cease erupting Hyst = Elodont - continue to erupt throughout the life of the animal
Describe the stomach of Rodentia
Monogastric
Glandular part of the stomach separated from forestomach by a ridge
Why can rodents not vomit?
- Prevented by stomach ridge
- Very strong oesophageal sphincter
- Crural sling that holds the stomach in the diaphragm is also strong
- Diaphragmatic muscles are too ‘weak’ to support emesis
Why do rodents not need to be starved before surgery?
High metabolic rate and fast gut transit time
How are rodents adapted for sufficient breathing?
Obligate nasal breathers
- Larynx is high in oropharynx
- Epiglottis is long so there is a passage straight from the nasal cavity to the trachea
Describe the lobulation of a rodents lungs
Left lung = single lobe
Right lung = Four lobes: cranial, middle, caudal, intermediate
Which species has a different lung anatomy, describe how it is different
Hamsters have an additional right lobe called the caudal accessory lobe
How is respiration optimised to make up for lung size?
- short airways and increased respiratory rates
- more alveoli of thinner diameter to increase SA
- High chest wall compliance = increased vital capacity
Describe the oxygen binding curve for rodentia
Shifted to the right in small animals
Harder to pick up oxygen
Haemoglobin releases oxygen readily at tissues
Helps meets the increased demand for oxygen by the tissues
What are some thermoregulation mechanisms?
- Shivering
- Nests, living underground, huddling
- Peripheral vasoconstriction e.g. tails, paws, ears
- Brown fat behind scapula and around neck
What are some mechanisms for heat loss?
- High surface area to volume ratio
- Minimal sweat glands (on feet only)
- Evaporation of groomed salvia on body
- Arteriovenous shunts in tail, ears and feet
A high surface area to body weight makes them susceptible to…?
- Dehydration
- Hypothermia
- Hypoglycemia
Compare the reproductive strategies of myomorpha vs hystricomorpha
Myo = altricial, large litter size, short gestation Hyst = precocial, small litter size, long gestation
Match the species with the following gestation lengths:
- 59-72 days
- 15-18 days
- 19-21 days
1 = guinea pig 2 = hamster 3 = mice
What is the oestrus cycle length for mice, rats amd hamsters?
4-5 days
Which Rodentia species reaches sexual maturity first?
Guinea pigs (4-6 wo)
