Week 15: Body Systems - Reptiles

Question 1

What 4 orders are part of the class “Reptilia”

Answer 1

Chelonia (tortoises and turtles)
Crocodilia (caimans, crocodiles and alligators)
Sphenodonta (tuataras)
Squamata (amphisbaenians, lizards and snakes)

Question 2

Of the order “Squamata” and sub-order “Serpentes”, there are 11 families. Give 2 examples

Answer 2

Colubrids/colubridae (mostly non-venomous)
Boids/boidae (constrictors)

Question 3

What are 3 examples of Boids?

Answer 3

Boas
Anacondas
Pythons

Question 4

Define: “cranial kinesis”

Answer 4

Significant movement of skull bones relative to each other in addition to movement at the joint between the upper and lower jaw

Question 5

Which bone in snakes allows them to take on a very wide gape (almost 180 degrees)?

Answer 5

The quadrate bone
Located very caudally in the skull and articulates with both the mandible and the brain case

Question 6

Do snakes have a mandibular symphysis?

Answer 6

No - the two halves of the mandibles are joined by a flexible elastic ligament which allows width wise separation of the lower jaw

Question 7

What feature of the snake skull prevents the brain from damage while swallowing live prey?

Answer 7

The brain case is heavily ossified (and therefore very rigid)

Question 8

How do snakes detect sound?

Answer 8

As the snake moves along the ground, the end of the quadrate bone is in contact with the ground and can pick up/transmit vibrations via the columella to the middle ear

Question 9

What structure in snakes is the equivalent to the stapes bone in mammals?

Answer 9

Columella bone

Question 10

Do snakes have a sternum/costal cartilages?

Answer 10

No - the ends of the ribs attach via muscle to the inner surface of the ventral scales

Question 11

Are limbs absent in all species of snake?

Answer 11

No - some species (e.g., boas) have a vestigial pelvic girdle that can be seen in the form of external spurs

Question 12

Define: “vomeronasal organ”

Answer 12

A domed cavity which is lined with sensory epithelium linked to the olfactory nerve

Question 13

How is the tongue in snakes used as a sensory organ?

Answer 13

The tongue is used to collect odours in the air before the snake brings it back into its mouth and presses the forked ends of the tongue into the vomeronasal organ

Question 14

Through which structure does the tongue protrude out of the mouth in snakes?

Answer 14

Lingual fossa

Question 15

How can pit vipers detect infrared radiation?

Answer 15

They have an additional structure between the eye and nostril called the pit organ, which contains specialised infrared receptors

Question 16

Do lizards have a mandibular symphysis?

Answer 16

Yes - they have a much narrower gape than the snake due to this

Question 17

What structures are required to support the large orbits in lizards?

Answer 17

Scleral ossicles

Question 18

Do lizards have an external ear?

Answer 18

No - there is a shallow depression in which the tympanic membrane sits

Question 19

What is the purpose of a third eye in lizards?

Answer 19

Involved in circadian rhythms

Question 20

What does the tripartite shoulder consist of in tortoises?

Answer 20

Scapula (fused to the carapace via ligaments)
Acromion (project medially)
Coracoid process (project caudally)

Question 21

Why are the cervical vertebrae in tortoises flexible?

Answer 21

Allows the head to be retracted

Question 22

Do tortoises have a mandibular symphysis?

Answer 22

Yes - similar to the lizard

Question 23

Do tortoises have a mandibular symphysis?

Answer 23

Yes - similar to the lizard

Question 24

Do tortoises have a sternum?

Answer 24

No

Question 25

In tortoises, what are the trunk vertebrae fused to?

Answer 25

The upper part of the shell (carapace)

Question 26

Do tortoises have scleral ossicles?

Answer 26

Yes - their vision is highly developed (better than snakes and lizards!)

Question 27

Why might some species of snake have a prehensile tail?

Answer 27

To live in trees (arboreal locomotion)

Question 28

How are scales produced in snakes, and what is the advantage of this?

Answer 28

The epidermis thickens and folds to produce scales, allowing great expansion when consuming prey

Question 29

In snakes, what name is given to the clear covering of the eye which protects the cornea?

Answer 29

The transparent spectacle/brille