Reptiles!!!

Reptiles!!!
The Scaly Clan
Crested Gecko
Brookesia Cameleon

Class: Reptilia----to creep
About 9,000 species Fossils date back to 300 million years (Carboniferous period)
Lets start the day off rightclick the frilled lizard!

Characteristics
Bilateral symmetryEndoskeleton made of bone3 or 4 chambered heartEctothermicJaws have powerful crushing abilityInternal fertilization

Adaptations for development on land:
Dry, thick skin with scales-impervious to waterLimbs with five toes with claws for walking on land/diggingDeveloped lungs with alveoliAmniotic eggWater-conserving kidneys

Order Testudines Turtles
Shells-dorsal carapace and ventral plastron- made of an outer keratin layer and an inner layer of boneShell plates called scutesVertebrae fused to carapaceTurtles have sharp plates covering the jaws instead of teeth.Turtles have poor hearing, but a good sense of smell, acute vision, and color perception.Oviparous with internal fertilization

Order Testudines Turtles
Marine turtles- paired limbs modified into flippers and can grow to 2 meters in length weighing 700 pounds.Giant land tortoises- can weigh over 600 pounds and their low metabolic rate produces life spans exceeding 150 years.Box turtles- hinged plastron that allows full protection of their body.Snapping turtles- reduced shells that dont enclose the whole body, but fierce jaws are a good defense.

Snapping Turtle
Hawksbill Sea Turtle
Click to see an alligator snapping turtle!

Giant Land Tortoise
Box turtle
Spiny Softshell:Click to see GA turtles

Videos
http://video.nationalgeographic.com/video/kids/animals-pets-kids/reptiles-kids/turtle-loggerhead-kids/http://animal.discovery.com/tv-shows/river-monsters/videos/turtle-strikes-like-a-snake.htm

Order Squamata Lizards & snakes
This order is the largest, most diverse- 96% of the living reptiles.Skull loosely jointed at the jaw/allows squamates to seize and manipulate prey.Viviparity or live births are limited to squamates (often associated with colder climates.)

Lizards
Usually four limbs presentVisible ear openingsMoveable eyelidsAbility to lose tail at fracture plane-autotomyhttp://srelherp.uga.edu/lizards/

Iguanas represent a group of herbivorous new world lizards.Chameleons are arboreal lizards of Africa with extendable tongues for catching their prey.The American Gila monster and Beaded lizard are venomous lizards.Monitor lizards are large carnivorous lizards including largest lizard the Komodo dragon (now also believed to be venomous.)

Snakes
Lack limbs and eyelids (have transparent coverings)No ear openingsElongate bodyJaws can disarticulate-to swallow large preyFangsDifferent types of venom in venomous speciesHemotoxins- cause heavy internal bleedingNeurotoxins- paralyze nerve cells

Snakes are deaf to most sounds since they lack external ears like lizards.Jacobsons organs are the paired pits in the roof of the mouth used for smell. (best developed in snakes and lizards)http://srelherp.uga.edu/snakes/ Ovoviviparous snakes: CopperheadsRattlesnakesCotton mouthsGarter snakes

Snakes continued
Coral snakes are members of the cobra family that feature neurotoxic (attack nervous system) venom.Pit vipers, such as rattlesnakes, have hemotoxic venom for killing prey located through heat sensitive pits.Non-venomous snakes kill prey by constriction or biting & swallowing prey.

Videos
http://video.nationalgeographic.com/video/animals/reptiles-animals/snakes/http://animal.discovery.com/video-topics/wild-animals/reptile-videos/incredible-snake-videos.htm
In nature,yellow lipped sea kraitsfeed on eels. They also feed on small fish. The venom of the sea krait affects both muscles and nerves . It is 10 times more toxic than that of a rattlesnake. In fact, over 60 known species of sea snakes in the Pacific and Indian Oceans are venomous. In one bite,yellow lipped sea kraitscan give ten times the venom needed to kill an human.

Order Crocodilia Crocodiles, alligators, & caimans
Divided into the new world caiman and alligator, and the more widely distributed crocodiles.Four chambered heart, also found in birds and mammals.Tongue not protrusibleExhibit nest tending and some parental care

The Salt-water & Nile crocodiles can reach lengths 22 feet making them the largest reptiles.
The gavial is a fish-eating specialist from India.

Videos
http://video.nationalgeographic.com/video/kids/animals-pets-kids/reptiles-kids/alligator-hatchlings-kids/http://video.nationalgeographic.com/video/animals/reptiles-animals/alligators-crocodiles/deadliest-crocodile-jaws/
Caiman

Order Sphenodontida- Tuataras
Only 2 speciesFound on islands off New ZealandLizard-like but have different skull structures (2 rows of teeth in upper jaw/1 row in lower jaw)Well developed third parietal eye-detects lightBurrows in day/feeds on insects at nightConsidered living fossils- only survivor of an ancient group (others died out about 60 MYA)

Integument-Skin
Tough, dry skin covered with scales composed of keratin to protect against drying out and injuries.Epidermis and dermisNo glands

Ecdysis molting- shed skin (mostly in pieces, snakes in one piece)

Respiration
Reptile lungs are better developed than amphibians and responsible for almost all gas exchanges (cloaca used by some.)Have alveoli-increase surface area of the lungsSuck air in by enlarging the thoracic cavityNo diaphragm

Circulation
Closed with both pulmonary and systemic systems Two separate circulations within the heartEither a complete partition separates the atria/ventricles or blood flow is such a way that oxygenated blood never mixes with unoxygenated bloodMost reptiles-3 chambered heart w/septumCrocodilians-4 chambered heart

Amphibian heart
Reptile heart

Nutrition & Digestion
Most are carnivoresVarious methods of getting foodVenomSticky tongueConstrictorsComplete digestive system

Excretion
Kidneys that are capable of processing wastes with little water lossElimination of nitrogenous wastes as uric acid-pastelike Many lizards possess salt glands below eyes-rids of excess salt

Nervous System
Small brain with large cerebrumWell developed sense organs (except hearing)

Jacobsons organ is a specialized olfactory organ. Scents are carried here by the tongue
Click

-eye sight-touch/feel-taste-smell

Blood sinus swells with blood to force debris to corner of eye-horned lizards rupture this sinus as a defense mechanismPit organs-detect temperatures different from their surroundingsSea turtles may be able to use the Earths magnetic field for navigation
Click to see the horned lizard in action!

Reproduction
Sexual reproduction with internal fertilizationOviparousEgg covered by a tough porous shellEggs are laid in sheltered locations on land

Development
Development begins in the eggTemperature can dictate the sex of the animal low=male/high=femaleYoung hatch as lung-breathing juveniles

Amniotic Egg
A shelled egg contains food and protective membranes to support embryonic development.The egg has broken the amphibian link to the water more than any other adaptation.

Amnion-thin membrane of fluid that encloses embryoYolk sac- (yellow part) food sourceAllantois- removes waste and functions as a lungChorion- gas exchange