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)