exotic comparison

Question 1

3. Describe the key structures of the reproductive system of a male snake in comparison to a male dog.

Answer 1

Dog
testes Lie externally in the scrotum

Question 2

Describe the process of respiration of the bird in comparison to cats. (8 marks)

Answer 2

Birds do not possess a diaphragm (1) to aid with respiration where cats do.
Bird have four stages to their respiration cycle. On first inspiration air is taken in by the nasal cavity and divided into two streams (1).
Air travels to the caudal air sacs and a small amount to the lungs (1).
On first expiration air is moved from the posterior air sacs to the lungs (1).
During second inspiration air moved to the cranial air sacs. Finally, on second expiration air is moved out of the cranial air sacs and expired (1).
Cats posses a diaphragm (1). During inspiration the diaphragm contracts and raises/expands the rib cage (1).
On expiration the muscles relax causing the ribs to fall and the diaphragm to return to a relaxed position (1).

Question 3

Describe the differences of dentition of a lizard in comparison to a dog.

Answer 3

Lizards have four rows of teeth (1),
one to each jaw which is similar to dogs (1).
Their teeth are all peg-like in shape (1),
whereas dogs have incisors, canines, premolars, and molars (1).
Lizard’s teeth are continually replaced (1),
whereas, dogs have deciduous teeth which are replaced by their permanent teeth at roughly 6 months of age (1).
Lizards do not have fangs (1),
whereas dogs have canines (1).
Some lizards also have hollow teeth allowing venom from the sublingual venom glad ooze through them (1).

Question 4

Describe the key differences between the feline and avian skeleton.

Answer 4

Instead of forelegs the birds have wings
* Adapted with reduced number of bones (fused bones)
* Fusion of some bones compared to felines
* Thinner bones. Internal bony braces maintain strength
* Hollow bones (pneumatic) filled with air spaces
* Air sacs extend into some bones (example humerous)
* Keel adapted for muscle attachments for flight in avians compared to felines.
* Birds have a keratinised beak no teeth, which is lighter than the feline jaw and associated dentition.
* Synsacrum is fused in avians to support landing, this is not the case with felines.
* Uncinate process on ribs for muscle attachments and aid respiration.

Question 5

Identify the key differences of digestion in rabbits compared to canines.

Answer 5

Rabbits are monogastric herbivores meaning they are hindgut fermenters. Canines are omnivores and have a relatively short GI tract – digestion in mainly main up of mechanical and enzymatic digestion.
Mechanical digestion in the mouth – rabbits grind laterally, dogs ‘chew’ using large masseter muscles.
Dogs have a relatively short GI tract – The rabbit GI tract is long in comparison.
In dogs Digestion begins during mastication via enzymes secreted by the salivary glands . These enzymes are found throughout the digestive tract and continue to break down food. In rabbits’ food is initially ground down mechanically using the cheek teeth and mixed with saliva. In the stomach only soluble fibers can be digested enzymatically. Long indigestible fibers are passed into the caecum to undergo bacterial fermentation.
Rabbits have a well-developed Caecum in order to ferment plant material dogs do not possess a Caecum
Canines pass faeces via the rectum. Rabbits also pass faeces via the rectum but carry out coprophagy. Caecotrophs are nutrient dense pellets eaten directly from the anus – they undergo digestion a second time in order to extract essential vitamins and amino acids.

Question 6

what the the difference between a dog and rat spinal column

Answer 6

A dog has 7 lumbar vertebrae – a rat has 6.

A dog has 3 sacral vertebrae (fused) – a rat has 4 (fused).

Rats have more coccygeal vertebrae than dogs – 27 to 31. Dogs usually have around 21 (20-23).