Reptiles Flashcards
How many openings does the reptilian skull have and why?
Two; openings (fenestration) provide additional surface for muscle attachment (Diapsid) giving more power to the jaw for hunting prey.
What are Chelonians and what is unique about their skull?
Turtles; have lost their skull fenestration and have now an anapsid skull.
What features of reptilian skin limits water loss?
Dry/scaly, permanent stratum corneum (moulting), beta-keratin makes skin more rigid.
What features of the amniotic egg meant it was evolutionarily successful ?
Calcium-impregnated shell prevents evaporation of fluids inside but allows gas exchanges, large quantities of yolk allows embryo to attain a relatively advanced state of development before it hatches (no metamorphosis).
What kind of teeth do reptiles have?
Turtles have a horny beak, all other reptiles have them teeth on both the palate and the jaws, most have homodont dentition however partial heterodoxy occurs in snakes (i.e. fangs).
How did orientation of limbs change from amphibians to reptiles?
In amphibians, orientation is outward from main axis, however in reptiles the appendages are rotated towards the body meaning the limbs are more parallel to main axis.
Why is parallel limb orientation important for reptiles?
Provides better support for the weight of the body and makes greater agility and speed possible.
Give an overview of reproduction in reptiles?
Internal fertilisation, males have a copulatory organ, females can store sperm for months, most species are oviparous.
What do viviparous reptiles exhibit?
A placentae formed by the appositions of maternal and embryonic tissues.
What are the sexual chromosomes most reptiles?
XY Male /XX Female
What is the less likely sexual chromosomes of reptiles i.e. Komodo dragons?
WZ Female /WW Male
What term is given to sex determination in reptiles?
Temperature dependant sex determination
What sex does high incubation temperatures cause in turtles?
Females
How can the Viviparous lizard select the sex of her embryos?
Can influence gestation temperature by basking behaviour.
What is Parthenogenesis?
Complete absence of male contributions; no sexual reproduction
What species exhibit parthenogenesis?
Whiptail lizards, geckos and blind snakes.
How do reptilian lung differ from that of amphibians?
More developed; divided into chambers and sub-chambers (faveoli) which increase the surface area for gas exchange.
What is unique of turtle respiration?
Some gas exchange takes place inside the mouth, in the cloaca and across the leathery skin that covers the shell.
What term is given to the type of breathing reptiles use?
Negative pressure breathing.
Describe how most reptiles breathe?
They have no diaphragm, but expand and compress the body cavity by movements of the ribs produced by contracting the intercostal muscles.
How come some lizards can only run for 1-2 minutes?
Lateral movements to the left compress the left lung and vice versa. Air is pumped between lungs but little in/out through the trachea.
Why do snakes have a single dominant left lung?
The anterior part is non-respiratory and instead functions as an air sac, glutei help respiration when ingesting large prey.
Describe the key features of lungs in turtles?
Lie within protected ridged shell, fixed rib cage cannot act to ventilate lungs, they have specialised sheets of muscle within the shell that contract and relax the lungs, air pressure in lungs can be changed by moving limbs in and out.
What type of air flow do alligators exhibit?
Unidirectional.
What differs with the heart of crocodilians?
The separation of the ventricles in complete (4 chambered heart) and an incomplete septum which reduces mixing of blood.
What kind of vision do reptiles that are active during the day use?
Reptiles that are active during the day have complex eyes (rods and oil droplets) that can see colour well.
What kind of vision do reptiles that are active at night use?
Lizards have large pupillary and lens aperture, and snakes use infrared vision.
What organ do some snakes have for infrared vision?
Pit organ.
What does the vomeronasal organ do?
Located on the palate to detect chemicals via the tongue.
How can you tell how much the vomeronasal organ is used?
Degree of the fork of the tongue.
How does the pit organ in snakes work?
Detection of infrared radiation > transient receptor potential channels > activates thermosensors in the vertebrate nervous system .
What structure detects airborne vibrations in reptiles?
External visible tympanic membrane.
What structure detects ground vibrations in reptiles?
The quadrate which forms part of the jaw joint.
What term is given to reptiles’ thermoregulation?
Ectotherms
What belongs to Squamata?
Lizards and snakes
How can snakes be distinguished from legless lizards?
Lack of eyelids, external ears and ear opening.
What family contains most of the snake species?
Colubroidea.
