14.4 Reptiles

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14.4 Reptiles
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Reptile Characteristics

• Reptiles are ectotherms.
• Their skin is dry thick and waterproof.
• Their skin is covered with scales which makes it
  waterproof and provides protection.
• Use their behavior to modify their body temp.

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Body Systems

• The waterproof skin prevents the exchange of
  gases.
• The circulatory system of reptiles is more
  developed than amphibians.
• Most have a three chambered heart with a partial
  wall between the third.
• Prevents the mixing of oxygenated blood.

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Amniotic Egg

• Reproduction is on of the most important
  adaptations for life on land.
• Reptiles use internal fertilization.
• The female lays eggs that are covered with a
  leathery shell which prevents water loss.
• The amniotic egg is a complete environment for
  the embryo.
• The egg contains everything that the embryo needs.

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Lizards and Snakes

• The lizards and snakes are the largest group of
  reptiles.
• Have a specialized jaw joint that can unhinge to
  make the mouth larger.
• Lizards have moveable eyelids, four legs,
  external ears and claws.
• Lizards eat other reptiles, insects, spiders,
  worms and mammals

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Snakes

• Snakes have developed ways to move on land
  without legs.
• Snakes have poor hearing and most have poor
  eyesight.
• Instead of hearing snakes can feel vibrations
  through the ground.
• Snakes are carnivores that swallow their food
  whole.
• Internal fertilization produces eggs some eggs
  hatch inside the body before being released.

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Turtles

• Are the only reptiles that have a two part bone
  shell.
• The vertebrae and ribs are fused to the inside of
  the shell.
• Turtles have a beak and no teeth.
• Turtles take little or no care of their
  offspring. (dig a hole and drop eggs in)

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Crocodiles and Alligators

• Are found in or near warm water.
• Crocs have a narrow head and triangular snout.
• Gators have a broad head and rounded snout
• Alligators are less aggressive than crocs.
• Crocs and gators are the few reptiles that take
  care of their young.

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Importance of reptiles

• Reptiles are important in controlling pest
  animals.
• Are fragile in their reproduction because they do
  not attend to the eggs.

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Origins

• First appeared in the fossil record 345 MYA
• Began to dominate land about 200 MYA
• Some reptile eventually returned to water but
  still returned to land to lay eggs.
• Died out about 65 MYA