3# of Species of Reptiles Species Numbers by Higher Taxa:Amphisbaenia (amphisbaenians) 165Sauria (lizards) 4765Serpentes (snakes) 2978Testudines (turtles) 307Crocodylia (crocodiles) 23Rhynchocephalia (tuataras) 2Reptiles total 8240
4Reptile Characteristics EctothermicDry skin covered in scalesMost have 2 pairs of short legs & clawed feetOviparous reproduction (Internal fertilization – to avoid desiccation of gametes)Eggs have a leathery shell and yolk (amniotic)Lungs to breathe3 or 4 chambered heartNo metamorphosis (young look like miniature parent)Hibernate & aestivate
5EctothermyBody temperature regulated by ambient air temperature
6Dry Scaly SkinThe body of reptiles is covered with horny epidermal scales to reduce water loss and provide protection.
7Reptile Legs Short tetrapods for walking Positioning of the legs more directly under the animal. This position provided more support than the splayed arrangement of the Amphibian legs.
8Paired LimbsThe paired limbs usually have five toes and are variously adapted for:SwimmingRunningClimbing(Absent altogether in the snakes)
12Amniotic Egg Structures & Functions Chorion provides a special hard covering that is permeable to respiratory gases (O2 and CO2) while being impermeable to water vapor.Allantois is a storage reservoir for metabolic waste products such as nitrogenous compounds.Amnion is a fluid filled sac that acts as a cushion for the embryo and also prevents desiccation.Yolk sac contains food for the embryo, thus eliminating the need for a larval stage.
15Reptile LungsRespiration is no longer through the skin, but only through internally protected and moistened lungs.They have a much greater surface area for the exchange of gases.They are inflated and deflated by the expansion & contraction of the rib cage.
16Reptile Hearts Reptiles have a 3-chambered heart Crocodiles have a 4-chambered heart
20Excretory WasteThe excretory waste of the reptiles is uric acid unlike the dilute, water wasting ammonia in the urine of Amphibians.
21Family Amphisbaenidae (Worm Lizards) Size: The total body length ranges from 10 cm to about 70 cm.Distribution: Mostly Africa & South America with a few species in Europe and North America.Habitat: Soil.Reproduction: usually oviparous, but some are live-bearing
45The temperature inside the nest of several crocodilian species decides the sex of the young. ~50-80 eggsIf the nest temperature is 30ºC, females will hatch from all the eggsIf the temperature is above 34ºC, all will be males.If the temperature is in between, there will be young of both sexes.