Chapter 20-Reptiles http://player.discoveryeducation.com/index.cfm?guidAssetI d=63C88B7F-A656-43DD-83E5-F640422CEFB4&blnFromSearch=1&pr oductcode=US
Mar 27, 2015
Chapter 20-Reptiles
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Class Reptilia
• Snakes, lizards, skinks, turtles, and crocodilians• Strong, bony skeleton and toes w/claws• Ectothermic metabolismEctothermic metabolism• Dry, scaly skin• Amniotic eggsAmniotic eggs• Respiration through well-developed lungs• Ventricle of heart partly divided by a septum• Internal fertilization
Ectothermic MetabolismEctothermic Metabolism
• Metabolism too slow to generate own body heat
• Intolerance to cold-become sluggish and unable to function
• Absorb heat from environment– BaskingBasking in sun to heat up– Shade to cool down– Maintain relatively constant by alternating
Sun Basking
Water Retention
• Do not lose water through skin or require water to reproduce like amphibians
• Skin -light and flexible scales
• Overlapping minimizes water loss
• Enables reptiles to live in dry environments
Overlapping Scales
Watertight Eggs
• Fertilized eggs need moisture to develop
• Internal fertilization allows for moisture to surround eggs
• Amniotic eggAmniotic egg- Tough-shelled egg containing a water and food supply– Most reptiles– All birds– Some mammals
Amniotic Eggs
Respiration
• Lungs w/many folds increase gas exchanging surface
• Strong muscles attach to rib sage aid expansion and contraction of lungs
• Incomplete septum separates ventricle of heart– Crocodilians have completely
divided ventricle
• Complete septum separates atrium of heart
• More separation of oxygen-rich and oxygen-poor blood
• Oxygen delivered to body cells more efficiently
Reptilian Heart Structure
Reproduction• Internal fertilizationInternal fertilization- Male introduces semen
directly into females body– Protects gametes from drying out
• Oviparous (most)- Young hatch from eggs– Most cases parents do not protect
• Ovoviviparous (some)- Female retains eggs in body until just before hatching; sometimes hatching occurs in mother– Eggs less vulnerable to predation
• Nourishment of eggs from yolk
Order Squamata
• Includes lizards and snakes
• Lower jaw loosely connected to skull
• Mostly carnivores; some herbivores
• Mouth opens wide to accommodate prey
• Extremely successful predators
http://video.search.yahoo.com/video/play?p=komodo+dragons&ei=UTF-8&vm=r&fr=yfp-t-501&tnr=21&vid=000164848944
Order Squamata/Suborder Sauria- Lizards
• Mostly small (<30 cm)• Largest: Kimodo dragons (<3 m)• Tail may break off to avoid
predation (regenerates w/no vertebrae)
• Molt skin periodically• Include:
– Iguanas– Chameleons– Geckos– Anoles– Horned lizards– Monitors– Skinks
http://video.search.yahoo.com/video/play?p=jesus+lizard&n=21&ei=utf-8&js=1&vm=r&fr=yfp-t-501&tnr=20&vid=000163111524
Order Squamata/Suborder Sauria- Lizards
Green Iguana Veiled chameleon Leopard Gecko
Anole Texas horned lizard Nile monitor
Order Squamata/Suborder Serpentes- Snakes
• Legless w/no eyelids nor external ears– No pectoral girdle– Five-point movement in
jaw– Elastic ligament allows
lower jaw to spread– No chewing or cutting
teeth– Ovoviviparous– 2/3 in family Colubridae
and non-venomous
Gaboon viper
Green tree python
Order Squamata/Suborder Serpentes- Snakes
• Several hundred vertebrae
• Jacobson’s Organs- Depressions in roof of mouth detect smell
• Feeding: All snakes subdue prey and swallow whole– Constrictors squeeze prey
until suffocation• Anacondas, boas, pythons,
and king snakes
Ball python
http://video.search.yahoo.com/video/play?p=constrictor&n=21&ei=utf-8&js=1&vm=r&fr=yfp-t-501&tnr=20&vid=000164319803
Order Squamata/Suborder Serpentes/Family Boidae- Constrictor Snakes
Anaconda Emerald tree boa
Banded king snake Scarlet king snake
Order Squamata/Suborder Serpentes- Snakes
• Venomous snakes
– Modified salivary glands produce venom to inject into prey with grooved or hollow teeth
– Families:
• Elapidae- Cobras, kraits, mambas, taipans, and coral snakes
• Hydrophiidae- Sea snakes
• Viperidae- Rattlesnakes, moccasins, adders, vipers and copperheads
http://vimeo.com/3263747
Order Squamata/Suborder Serpentes- Venomous Snakes
Coral snake King cobra Krait
Sea snake Puff adder Eyelash viper
Order Squamata/Suborder Serpentes- Venomous Snakes
Water mocassin (a.k.a. Cottonmouth) Copperhead
Order Squamata/Suborder Serpentes- Rattlesnakes
• Rattle- 5 to 7 rings of keratin and protein• New ring each molt• Pit organ- Openings between eye and nostril detect infrared• Venom- Hemotoxin affects red blood cells causing
hemorrhaging
Timber rattlesnake Diamondback rattlesnake
Order Squamata/Suborder Amphisbaenia- Worm Lizards
• ~ 135 species
• Amphis – double; baen – to walk
– Move easily backwards and forwards
• Burrowers
• Unique single median tooth on upper jaw
• Annuli – ring-like folds in skin
• Oviparous – Feed on worms and small insects
Order Chelonia (Testudines)- Turtles and Tortoises
• 250 species• Body encased in shell
– Bony plates covered w/leathery skin
– Vertebrae fused to dorsal– Provides support for muscles– Some for protection– Carapace- dorsal part of the
shell– Plastron- Ventral
• No teeth;powerful beak• Many herbivores; some
carnivores
Gopher tortoise
Giant tortoise
Order Chelonia (Testudines)- Turtles and Tortoises
• Turtles- Stream-lined, disk-shaped shell for water movement
• Tortoises- Dome- shaped shell
Alligator snapping turtle
Box turtle Sea turtle
Order Crocodilia- Alligators, Crocodiles, Caimans, and
Gavials• Large aggressive carnivores• Capture prey by stealth,
drowns, and eats• Eyes and nostrils on top of
head to allow for seeing and breathing while under water
• Strong neck w/large mouth (100s of sharp teeth)
• Throat valve prevents water entering into lungs
• Uniquely care for young after hatching
Caiman
Gavial
Order Crocodilia- Alligators, Crocodiles, Caimans, and
GavialsAmerican alligator Nile crocodile
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Order Rhynchocephalia- Tuataras
• Native to New Zealand
• Lizard-like• Uniquely active at low
temp./night• Unchanged for 150
million yrs.• 2 species
– Genus Sphenodon