Week 15: Body Systems - Reptiles Flashcards
What 4 orders are part of the class “Reptilia”
Chelonia (tortoises and turtles)
Crocodilia (caimans, crocodiles and alligators)
Sphenodonta (tuataras)
Squamata (amphisbaenians, lizards and snakes)
Of the order “Squamata” and sub-order “Serpentes”, there are 11 families. Give 2 examples
Colubrids/colubridae (mostly non-venomous)
Boids/boidae (constrictors)
What are 3 examples of Boids?
Boas
Anacondas
Pythons
Define: “cranial kinesis”
Significant movement of skull bones relative to each other in addition to movement at the joint between the upper and lower jaw
Which bone in snakes allows them to take on a very wide gape (almost 180 degrees)?
The quadrate bone
Located very caudally in the skull and articulates with both the mandible and the brain case
Do snakes have a mandibular symphysis?
No - the two halves of the mandibles are joined by a flexible elastic ligament which allows width wise separation of the lower jaw
What feature of the snake skull prevents the brain from damage while swallowing live prey?
The brain case is heavily ossified (and therefore very rigid)
How do snakes detect sound?
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
What structure in snakes is the equivalent to the stapes bone in mammals?
Columella bone
Do snakes have a sternum/costal cartilages?
No - the ends of the ribs attach via muscle to the inner surface of the ventral scales
Are limbs absent in all species of snake?
No - some species (e.g., boas) have a vestigial pelvic girdle that can be seen in the form of external spurs
Define: “vomeronasal organ”
A domed cavity which is lined with sensory epithelium linked to the olfactory nerve
How is the tongue in snakes used as a sensory organ?
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
Through which structure does the tongue protrude out of the mouth in snakes?
Lingual fossa
How can pit vipers detect infrared radiation?
They have an additional structure between the eye and nostril called the pit organ, which contains specialised infrared receptors
Do lizards have a mandibular symphysis?
Yes - they have a much narrower gape than the snake due to this
What structures are required to support the large orbits in lizards?
Scleral ossicles
Do lizards have an external ear?
No - there is a shallow depression in which the tympanic membrane sits
What is the purpose of a third eye in lizards?
Involved in circadian rhythms
What does the tripartite shoulder consist of in tortoises?
Scapula (fused to the carapace via ligaments)
Acromion (project medially)
Coracoid process (project caudally)
Why are the cervical vertebrae in tortoises flexible?
Allows the head to be retracted
Do tortoises have a mandibular symphysis?
Yes - similar to the lizard
Do tortoises have a mandibular symphysis?
Yes - similar to the lizard
Do tortoises have a sternum?
No
In tortoises, what are the trunk vertebrae fused to?
The upper part of the shell (carapace)
Do tortoises have scleral ossicles?
Yes - their vision is highly developed (better than snakes and lizards!)
Why might some species of snake have a prehensile tail?
To live in trees (arboreal locomotion)
How are scales produced in snakes, and what is the advantage of this?
The epidermis thickens and folds to produce scales, allowing great expansion when consuming prey
In snakes, what name is given to the clear covering of the eye which protects the cornea?
The transparent spectacle/brille
