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Reptile
6S (13)
Lee Michelle Ching Yin
Me too!
We are reptiles!
Class: Retilia
General features:
• live on ground, while some can live in
water as well
• poikilotherm
• most are carnivorous, except turtles are
herbivorous
• breathe with lungs
• skin covered with scales/ scutes
• lay shelled eggs
• tetrapods
Body
Structure
•have lungs
- crocodiles: muscular diaphragm
increase space for greater lung
inflation
•have horny epidermis
watertight
able to live on dry land
•exposed parts protected by scales
& scutes
•have three-chambered heart
- 2 atria, 1 ventricle, 2 aortas
- deoxygenated blood can be shunted
back to the heart and oxygenated
blood can be shunted back to the
lungs
 more effective thermoregulation
 longer diving time

diurnal animals
-vision can adapt daylight condition
-with colour vision
-more advanced vision depth
•some snakes have heat-sensitive
pits
sense the body heat of birds and
mammals
hunt in the dark
•lack a secondary palate
- must hold their breathe while
swallowing
- except crocodiles & skinks
- snakes: extend their trachea and stick
out like a fleshly straw
•camouflage
-skin colour is usually grey, brown or green
blend into the background
of the natural environment
avoid confrontation
Reproduction
•most reptiles reproduce sexually
• all reproductive activities occur
through the cloaca
• most reptiles have copulatory organs,
which are usually retracted or
inverted and stored inside the body
•some squamates (lizards & snakes) are
able to have asexual reproduction
• parthenogenesis
• females are able to produce a unisexual
diploid clone of the mother
•oviparous
-most reptiles lay eggs covered with
leathery or calcareous shells
•ovoviviparous/ viviparous
- ovoviviparous= embryos develop
inside eggs, without placenta
- viviparous= birth of offspring without
the development of calcified eggs
- evolved only in lizards & snakes
• temperature-dependent sex
determination
- the incubation temperature determines
whether a particular egg hatches as male
or female
- most common in turtles and crocodiles
- sometimes occur in lizards and tuataras
as well
Defense
Mechanism
snakes
• crawl away into the underground
• hiss loudly
• vibrate the tip of the tail ( rattlesnakes)
• elevate the head and spread out the skin
of the neck to look bigger and
more threatening
• use venom to attack
• play dead
crocodiles
• expose the teeth and yellow tongue
• plunge into water and sink out of sight
• hiss loudly
• inflate the body to look bigger
• chase
• bite
lizards
• the tail has more vivid colour
• when captured by the tail
shed the part of the tail
• detached tail will continue to wiggle
•the tail can be regenerated
Reptiles
dry & scaly skin
with claws
breathe with lungs
eggs have thick, hard
shell
eggs laid in buried,
insulated nests
external fertilization
do not have larval
stage
Amphibians
moist & sticky skin
without claws
breathe with lungs & gills
eggs without protective
outing covering
eggs laid in water / damp
places
internal fertilization
pass through larval stage
before metamorphose into
adult form
The End!
Reference:
http://en.wikipedia.org/wiki/Reptile
http://en.wikipedia.org/wiki/Tempe
raturedependent_sex_determination
http://en.wikipedia.org/wiki/Parthe
nogenesis