ReptilesChapter 3 Section 4
K. Duff
Vocabulary Words
• Amniotic eggs• Squamata • Testudines • Crocodilia• Sphenodontia
Reptiles
• Inhabit every continent except Antarctica
• Classification:– Kingdom: Animalia
– Phylum: Chordata
– Class: Reptilia
Reptile Characteristics• Ectotherms
• Scales– Thick, dry waterproof skin
– Helps prevent waterloss
– Prevents against injury
• Respiratory System– Breathe through lungs
– Scales prevent breathing through the skin
• Circulatory System– 3 chambered heart with a partial wall
(septum)• Less mixing of CO2 and O2 blood
–More advanced than amphibians
• Crocs and alligators have 4 chambered hearts
• Reproduction
– Internal fertilization– Amniotic eggs
• Tough leathery shell keeps them from drying out on land
• Complete environment for the embryo’s development
• Young reptiles look like small adults (no metamorphosis)
• Most provide little to no care for their young
• Digestive System:– Can be omnivores, carnivores, and
herbivores
Orders of Modern Reptiles
1. Squamata - Lizards and Snakes
2. Testudines -Turtles
3. Crocodilia - Crocodiles and Alligators
4. Sphenodontia - Tuataras
Squamata – Lizards & SnakesLizards:
• Moveable eyelids
• External ears
• Legs with claws
• Some lizards can – Lose and re-grow their tails
as a defense mechanism
– Change color in response to stress
Snakes:
• No limbs
• Poor hearing and eyesight– Snakes “hear” vibrations from the ground
through their jaw
• Carnivores– Jaw unhitches (increases mouth size)
– Some constrict their prey (wrap around it)
– Some inject their prey with poisonous venom
• Elongated (stretched out) organs
• Use their Jacobson’s organ located on roof of mouth to follow trail of prey
• No eyelids – clean eyes with their tongues
Ways to Identify a Venomous Snake:
Testudines - Turtles• The only reptile to have a two part shell
made of hard bony plates
• The vertebrae, ribs, and muscles are attached to the shells
• These shells are used for protection against predators
• No teeth, mouth has powerful jaws and a beaklike structure used to crush food
What’s the difference between turtles and tortoises?
• Turtle = live on land and water
• Tortoise = lives only on land
Aldabra Giant Tortoise
Green Sea Turtle
Crocodilia- Crocodiles and Alligators
• Most advanced reptiles– 4 chambered heart– Cerebral cortex (part of the brain that is used for
memory, thought, and language)
• Large deep scales on their backs• Powerful jaws with sharp teeth
– They cannot open their mouths if their jaws are being held shut
• Care for their young until they can protect themselves
• The eyes of a large alligator will glow red and those of a smaller one will glow green when a light is shined on them. – This fact can be used to find alligators in
the dark.
Crocodiles vs. Alligators• Crocodiles:
– Narrow head, triangular shaped snout
– Very aggressive
– Greenish brown in color
– Found all over the world
• Alligators:– Broad head, rounded snout
– Less Aggressive
– Blackish in color
– Found only in SE USA and parts of China
Differences in Shape of Snout
American Alligator
Siamese
Crocodile
Sphenodontia - Tuatara• Called “living fossils”• Only two species remain in their order• Endangered since 1895• Only found in New Zealand• Resemble lizards and can re-grow their
tails, but they are different• Beak-like jaw: 2 rows of bony teeth on top,
1 on bottom• Hatchlings have a 3rd “eye” that becomes
covered with scales in adulthood
Parietal Eye
• Does not see images
• Photosensory organ – Sensitive to changes in light
The Importance of Reptiles
• Control pest populations (mice, snakes, rats)
• Their meat and eggs are used for food
• Skin is used for specialty items (wallets, boots, etc.)
Origin of Reptiles
• First appeared about 345 mya
• Hylonomus – Oldest-known reptile
– 8 to 12 inches (20 to 30 cm)
long
– Ate insects
Prehistoric Aquatic Reptiles:
– Ichthyosaur
– Champosaur
– Mosasaur
– Elamosaurus
– Plesiosaur (the Loch Ness Monster is reported to be similar to this
reptile)