Small Mammal A&P

Question 1

What are the main differences of the rabbit skeleton

Answer 1

1. Suprahamate bone (scapular process)
2. Distal 2/3rds of tibia and fibula are fused
3. Completely fused radius and ulna
4. Large pinnae. Very vascular and mobile.
5. Large lateral orbits
6. Powerful hindlimbs; short forelimbs for digging
7. Herbivore teeth

Question 2

Describe the digestive system of the rabbit

Answer 2

Monogastric with well-developed sphincters - rabbits cannot vomit.
Hind-gut fermenters/ non-ruminant herbivores
Coprophagy
Liver has 4 lobes
Small intestine is long and terminates at caecum (where fermentation of plant material takes place) at the sacculus rotundus (swelling of gut between ileum and caecum). Then onto colon.

Question 3

State the dental formula of rabbits

Answer 3

I 2/1 C 0/0 PM 3/2 M 3/3

Question 4

Describe rabbit teeth

Answer 4

Open-rooted
Continuously growing
Elongated Jaw
PM and M often referred to as ‘cheek teeth’
Diastema is the gap between the incisors and molars
2nd pair of incisors are vestigial and lie behind 1st pair

Question 5

Describe rabbit respiration

Answer 5

Diaphragm is the primary mechanism for respiration
Don’t really use chest muscles
Obligate nose breathers - due to position of the epiglottis
Lungs have 3 lobes in each - cranial lobes are small.
Left lung is smaller than right.

Question 6

Describe the urinary system of rabbits

Answer 6

Calcium is excreted in urine 
(in other animals, its excreted in bile)
Turbidity/ cloudiness of urine is dependent on calcium deposits
Produce a lot of urine 
Huge colour range

Question 7

Describe the reproductive system of rabbits

Answer 7

Bicornuate uterus - 2 uterine hones
No uterine body
Double cervix
Induced ovulators. Altricial young.
Don't have distinct heat cycles
4 or 5 pairs of mammary glands
Each side can function independently

2 testes in 2 scrotal sacs, cranial to penis.
No os penis
open inguinal ring allows retraction of testes into abdomen.

Question 8

What group of animals do guinea pigs fall into?

Answer 8

Hystricomorphs

Question 9

Describe the digestive system of guinea pigs?

Answer 9

Very similar to rabbits.
Also exhibit coprophagy - 2nd pellet is not as dry as rabbits. 
Herbivores
Hind-gut fermenters
Monogastric
Large caecum
Relatively long small intestine
6-lobed liver

Question 10

What is unique about guinea pigs?

Answer 10

They cant produce their own vitamin C

Question 11

What are myomorphs?

Answer 11

Rats, gerbils, mice and hamsters

Question 12

Describe the teeth of myomorphs

Answer 12

Open rooted incisors and rooted molars
I 1/1 C 0/0 PM 0/0 M 3/3 = 16
Diastema between incisors and molars.

Question 13

Describe the digestive systems of myomorphs

Answer 13

Designed to breakdown a varied diet
Caecum doesn’t ferment so have a longer gut
Herbivorous material moves slowly through the small intestine to accommodate the breakdown of this

May or may not produce caecotrophs
Rats lack a gall bladder
Hamsters have a distinct fore-stomach

Question 14

Describe the reproductive system of myomorphs

Answer 14

Bicornuate uterus. Little or no uterine body.
Spontaneous ovulators.
Female rats have 5 pairs of teats.
Female hamsters have 6 pairs of teats

2 testes in external scrotum - can return to abdomen via open inguinal canal in some species.
Have os penis

Question 15

What is unique about hamsters?

Answer 15

Have flexible pouches to store food
Little tail stump - no tail
Very small, shallow eye sockets

Question 16

What is unique about gerbils?

Answer 16

Prehensile tail used to balance

Can shed their tail as a defence mechanism

Question 17

Describe the feet of rabbits

Answer 17

No footpads
5 toes on forefoot; 4 on hindfoot
Entire foot lies flat on ground from toe to hock.

Question 18

How many vertebrae do rabbits have?

Answer 18

C7 T12-13 L7 S4 C16

Question 19

Describe the lips of the rabbit?

Answer 19

Have split upper lip - philtrum

Question 20

Describe guinea pig teeth?

Answer 20

I 1/1 C 0/0 PM 1/1 M 3/3 = 20.

Incisors and cheek teeth are open rooted and continuously growing.

Question 21

Describe the skeletal anatomy of guinea pigs?

Answer 21

No tail, 4-6 vestigial coccygeal vertebrae.
C7 T13-14 L6 S2-3 C4-6
Short, stocky legs
4 toes on forefeet; 3 on hindfeet.
Small ears

Question 22

Describe the feet on hamsters, rats and mice?

Answer 22

4 toes on front feet and 5 toes on hind feet

Question 23

Describe the reproductive system of guinea pigs?

Answer 23

Both male and female have a pair of long inguinal nipples
Bicornuate uterus and 1 cervix
Have an os penis.