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REPTILIA

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  • pg 1
									REPTILIA
Characteristics of reptiles that
distinguish them from amphibians
• 1. Amniote egg
  – Reptiles probably evolved from amphibians
  – Allowed for reproduction on land
  – Self-contained nursery for developing
    embryo
– Amniotic sac
  • Amnion: thin membrane enclosing the salty
    fluid in which the embryo floats
  • Yolk sac: encloses the yolk, a protein-rich food
    supply for the developing embryo
  • Allantois: stores nitrogenous wastes produced
    by the embryo
  • Chorion: lines the outer shell
     – Regulates the exchange of oxygen and carbon
       dioxide between the egg and outside environment
• Shell is leathery and waterproof
• Internal fertilization takes place since sperm
  cannot penetrate shell
• 2. Waterproof skin
  – Tough, dry, scaly skin
  – Contain chromatophores: color bearing
    cells
  – Scales made of keratin
  – Scales prevent water loss and provide
    protection
• 3. External Structural Adaptations
  – Some reptiles have toes with claws that
    permit climbing and digging
  – Some have suction cups that aid in
    climbing
  – Snakes rely on their highly developed
    skeletal and muscular systems for
    movement
• 4. Respiration
  – All breathe through lungs
  – Tissues are inside body, thus kept moist
• 5. Circulation
  – More complex, provides more oxygen to
    the body
  – 3 chambered heart for most, gators and
    crocs have 4
  – Oxygenated and deoxygenated blood can
    be separated
• 6. Excretion
  – Conserve water by excreting nitrogenous
    wastes in dry or pasty form
• 7. Temperature regulation
  – Ectothermic (cold-blooded)
  – Rate of metabolism is controlled partially
    by temperature
  – May bask in sun to increase metabolic rate
    or seek shade to prevent overheating

								
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