Reptiles Keith Hua Michael Wu

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ReptilesKeith Hua Michael Wu
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Taxonomy

• Domain Eukarya
• Kingdom Animalia
• Phylum Chordata
• Class Reptilia

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Reptiles

• Reptiles have an endoskeleton, closed circulatory
  system, notochord, nerve cord, pharyngeal slits,
  and a tail.
• Reptiles are highly cephalized just like human.
• The first appearance of the reptile was
  300,000,000 years ago, and the first known
  reptile was the Hylonomus.
• Reptiles have many defensive mechanisms.
• Some snakes like cobras and rattlesnakes inject
  poison through their fangs made from venom glands
  behind their eyes.
• The two main types of venom poison are
  neurotoxins (nerve poisons), and hemotoxins
  (blood and tissue poisons).
• Crocodiles just bite their enemies, or use their
  tails for protection. Crocs have a bite force of
  3000 pounds per square inch.
• Reptiles usually like to live in warm climates
  like tropical rainforests, warm waters, and
  deserts since they are cold-blooded.

Hylonomus first reptile
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Respiratory System

• Since reptiles breathe less they have less spongy
  and more hollow lungs, which makes it less
  efficient at getting oxygen.
• Most reptiles also do not have diaphragms so they
  have to breathe by moving their ribs or throats.
• Some reptiles like turtles however have permeable
  skin for gas exchange, and other species have
  modified their cloaca to increase the area of gas
  exchange.
• Because of a turtles shell however turtles
  cannot breathe like other reptiles, instead there
  is a sheet of muscle that envelops the lungs and
  when it contracts the turtle exhales, and when it
  protracts it can inhale.
• Crocodiles have muscular diaphragm that pulls the
  pelvis back to make room for the lungs to expand.
• Snakes have 2 lungs however the right lung is way
  bigger than the left lung, and a snake may move
  its windpipe off to the side to continue
  breathing as its feeding.
• Snakes have a trachea, air sac, and bronchi. The
  left bronchi leads to the left lung which is
  small and non-functioning, and the right bronchi
  leads to the right lung which is elongated.
• The forward portion of the snakes lungs function
  for gas exchange and the second half is the air
  sac which extends to the tail. The air sac
  regulates pressure inside the body cavity.

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Respiratory System
A. TracheaB. EsophagusC. ThymusD. ThyroidE.
HeartF. Vestigial left lung
G. Right lungH. Air sacI. LiverJ. Gall
BladderK. StomachL. Spleen
M. PancreasN. Testis (right)O. Adrenal glandP.
Ductus deferensQ. Kidney (right)R. Ureter
S. ColonT. CloacaU. Scent glandsV.
HemipenesW. Small intestine
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Circulatory System

• Reptiles have a closed circulatory system similar
  to humans.
• Most reptiles have 3 chambered hearts consisting
  of 2 atria, two aortas, and a partially separated
  ventricle, while some have an actual divided
  ventricle.
• In some conditions aquatic reptiles can move
  their deoxygenated blood back to the body and
  their oxygenated blood to their lungs for longer
  dive times.
• Crocodiles on the other hand have a 4 chambered
  heart, and can bypass their pulmonary
  circulation, which carries oxygen depleted blood
  to the lungs and oxygenated blood to the heart.
• Pythons and some lizard species have a 3
  chambered heart, but is capable of changing it
  into a 4 chambered heart during contraction. A
  muscular ridge subdivides the ventricle making it
  4 chambered.
• The right and left atria receive blood from the
  lungs and body, and pass it to the ventricle to
  be circulated again.
• The snakes heart is encased in a sac called the
  pericardium that is located at the branching of
  the bronchi, that enables the heart to move
  around but not be harmed when digesting large
  prey.

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Circulatory System
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Nervous System

• Reptiles have the same basic parts of the
  amphibian brains, except they have larger
  cerebrums and cerebellums.
• Reptiles have 12 pairs of cranial nerves like
  humans, and unlike mammals their spinal cords
  extend to the tip of their tails.
• These cranial nerves help reptiles see, smell,
  and eat.
• A reptiles brain however is still relatively
  small.
• Reptiles have highly developed sense organs,
  except for the fact that snakes dont have
  external ears.
• A snakes tongue includes highly sensitive smell
  sensors that can pick up odor particles.
• Snakes also have one special organ called the
  Jacobsons organ located in the snout but behind
  the nostrils. This organ chemically analyzes
  particles that the snake may pick up.
• The Jacobsons organ also allows snakes to find
  mates, and identify food and predators.
• Crocodiles have extremely good eyesight due to
  their cat-like eyes and may even have color
  vision similar to humans
• Crocs have sensory pits in their lower and upper
  jaw that contain nerve fibres to detect
  disturbances in the water.

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Nervous System
Snakes Jacobsons organ that chemically analyzes
particles.
Crocodiles cat-like eyes enable them to see in
the dark.
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Digestive System

• A reptiles digestive system includes the
  esophagus, stomach, small intestine, and large
  intestine.
• Snakes do not chew their food, instead they eat
  their food whole.
• The food first enters the esophagus, and into the
  stomach of the snake, then the stomach breaks the
  food down but secreting hydrochloric acid. The
  food then goes to the small intestines, and the
  waste is passed into the large intestine and then
  the cloaca and it is then excreted out of the
  body.
• The snakes liver and pancreas also secrete
  digestive enzymes to help the breaking down of
  food.
• Since crocodiles dont chew their food because
  their teeth arent well aligned they usually
  swallow their food whole.
• Crocodiles have 2 stomachs, 1 is a muscular
  gizzard, and the other has powerful acids to
  further break down the food.
• Turtles try to rip their food to small pieces
  using their claws, feet, an essentially one big
  tooth.
• Crocodiles, snakes, and turtles may go up to
  weeks or months without eating as they slowly
  digest large meals.

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Digestive System
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Reproduction

• Most reptiles reproduce sexually, however some
  kind reproduce asexually.
• All reproductive activity occurs through the
  cloaca.
• Males and females usually put their cloaca
  together and the male excretes sperm.
• Most reptiles lay eggs in the ground, or some
  species retain their eggs until they are just
  about to hatch and then lay them down.
• Not all reptiles lay eggs, some snakes like
  rattlesnakes, garter snakes, and water snakes may
  give birth to live young.

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Excretory System

• Reptile excretion is performed by 2 main kidneys.
• Uric acid is the main waste product, but urea is
  the main product for turtles.
• Since reptiles cannot produce liquid urine more
  concentrated than their body fluid their large
  intestines (colons) help absorb excess water.
  Bladder helps do this too.

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Turtles Respiratory System