rodents

Question 1

which taxonomic order are rodents of

Answer 1

rodentia

Question 2

what characterises rodents

Answer 2

continuously long growing incisors

Question 3

myomorpha

Answer 3

mouse like

Question 4

hystricomorpha

Answer 4

guinea pig, chinchilla, degu

Question 5

dental formula myomorpha

Answer 5

i 1/1, c 0/0 pm 0/0 m 3/3 = 16 teeth

Question 6

hystricomorpha dental formula

Answer 6

i 1/1 c 0/0 pm 1/1 m 3/3 = 20 teeth

Question 7

rodent dentition features

Answer 7

open rooted, constantly growing incisors
open rooted premolars and molars
large diastema
gnaw without wearing molars or swallowing debris;
lower jaw moved forward
incisors opposed but molars are not
cheeks drawn into diastema

Question 8

incisors features

Answer 8

chisel shaped
open rooted = aradacular
continually growing = elodont
hard enamel on one side

Question 9

difference of molars

Answer 9

myomorphs = anelodont
hystricomorphs = elodont

Question 10

gastrointestinal system

Answer 10

monogastric
glandular part of stomach separated from forestomach by ridge
large caecum
elongated colon - enhances uptake of essential vitamins and amino acids
CANNOT vomit

Question 11

respiratory features

Answer 11

obligate nasal breathers
left lung = single lobe
right lung = 4 lobes - cranial, middle, caudal, intermediate - hamster also has caudal accessory
oxygen requirements high
thinner diameter in alveoli

Question 12

thermoregulation mechanisms for thermogenesis

Answer 12

behavioural - huddling, nest building
shivering
peripheral vasoconstriction

Question 13

reproductive system (female)

Answer 13

bicornuate - guinea pig
duplex - rat, mouse, hamster, gerbil (2 cervix)

Question 14

sexing rodents method

Answer 14

ano-genital distance = longer in male than female