ReptilesReptiles

General CharacteristicsGeneral Characteristics

ClassificationClassification Phylum ChordataPhylum Chordata

Subphylum VertebrataSubphylum Vertebrata

- Class Reptilia- Class Reptilia

Order Squamata- Lizards & SnakesOrder Squamata- Lizards & Snakes

Order Testudine- Turtles & Order Testudine- Turtles & TortoisesTortoises

Order Crocodilia- Crocodiles & Order Crocodilia- Crocodiles & AlligatorsAlligators

Order SquamataOrder Squamata

Order TestudineOrder Testudine

Order CrocodiliaOrder Crocodilia

HerpetologyHerpetology

The field of science that studies The field of science that studies reptiles and amphibians.reptiles and amphibians.

SkinSkin

Dry thick skin covered with scales; Dry thick skin covered with scales; Scales are part of the skin- all connectedScales are part of the skin- all connected

Scales provide protection from water loss Scales provide protection from water loss and protection from predators.and protection from predators.

Scales are made of keratinScales are made of keratin Keratin is protein in the epidermis, often Keratin is protein in the epidermis, often

modified into nails, horns, and hairmodified into nails, horns, and hair

Skin cont…Skin cont…

Skin consists of 2 Skin consists of 2 layerslayers Epidermis- thin layer, Epidermis- thin layer,

and shed periodicallyand shed periodically Dermis- Thicker layer, Dermis- Thicker layer,

contains contains chromatophores chromatophores which give reptiles which give reptiles their colortheir color

AppendagesAppendages

Paired limbs Paired limbs Usually 5 toes with clawsUsually 5 toes with claws Limbs located under body provides more Limbs located under body provides more

support for walking and running on land.support for walking and running on land. Limbs absent in snakes and some Limbs absent in snakes and some

lizards.lizards.

RespirationRespiration

All reptiles breathe through All reptiles breathe through LungsLungs..

CirculationCirculation

Most reptiles have 3 chambered hearts.Most reptiles have 3 chambered hearts. Crocodiles have a 4 chambered heart Crocodiles have a 4 chambered heart

that enables more oxygen to reach body that enables more oxygen to reach body tissues.tissues.

EctothermicEctothermic

All reptiles are ectothermic.All reptiles are ectothermic. Do not inhabit extremely cold regions.Do not inhabit extremely cold regions. Live in temperate, tropical and desert Live in temperate, tropical and desert

climates.climates.

ReproductionReproduction

Reptiles do not need water to reproduce.Reptiles do not need water to reproduce. Separate SexesSeparate Sexes Internal FertilizationInternal Fertilization Most lay leathery or calcareous eggs, Most lay leathery or calcareous eggs,

with the embryo developing after the egg with the embryo developing after the egg is laidis laid

Young look like small adultsYoung look like small adults Most do not provide parental care.Most do not provide parental care.

The Amniotic EggThe Amniotic Egg

The evolution of the amniotic egg was The evolution of the amniotic egg was the adaptation that freed reptiles from the adaptation that freed reptiles from dependence on water for reproduction.dependence on water for reproduction.

Amniotic Egg is a shelled egg that Amniotic Egg is a shelled egg that contains food and protective membranes contains food and protective membranes for supporting embryonic development.for supporting embryonic development.

Parts of the Amniotic EggParts of the Amniotic Egg

1. amnion- cushions; prevents 1. amnion- cushions; prevents dehydrationdehydration

2. outer shell- protection2. outer shell- protection 3. allantois- waste sac3. allantois- waste sac 4. yolk- food supply4. yolk- food supply 5. albumin- additional food5. albumin- additional food 6. chorion- gas exchange6. chorion- gas exchange