Reproductive Strategies

• Where does external fertilization take place?

  Water
• What type of vertebrates use external fertilisation?

  Aquatic
• What type of vertebrates use internal fertilisation?

  Terrestrial
• What type of fertilisation does not use water to transport sperm (external/internal)?

  Internal
• What type of fertilisation has eggs develop outside?

  Ovipary
• Ovivivipary:

  • Eggs are fertilised internally
  • Eggs are kept inside then hatch internally
• OVOVIVIPARY:

  • eggs are fertilised internally
  • eggs are kept inside then hatch internally
• Advantages of external fertilisation:

  • large number of gametes to avoid predation
  • courtship rituals bring gametes closer
• Advantages of internal fertilisation:

  • Fertilisation is more certain
  • fewer gametes needed
  • protective shell/yolk
• Disadvantage of external fertilisation

  • wasteful number of eggs
  • fertilisation not certain
• Disadvantages of internal fertilisation:

  • finding a mate
  • fewer reproduction opportunities
  • longer gestation
• Advantages of ovipary:

  • Aquatic: many eggs with small amounts of yolk (less energy)
  • Land: very few eggs (more yolk, more protection, parental care)
• Disadvantages of ovipary:

  • aquatic: often very little parental care
  • land: susceptible to predators
• Advantages of ovovivipary:

  • large amount of yolk
  • protection from predators
  • young born fully developed
• Advantages of vivipary:

  • reduced egg numbers
  • nourishment & protection
  • provide parental care
• Label the amniotic egg

  A) SHELL

  B) YOLK SAC

  C) ALBUMIN

  D) ALLANTOS

  E) EMBRYO

  F) AMNIOTIC FLUID

  G) AMNION

  H) CHORION

  
• Which part of the amniotic egg provides protection and prevents dehydration?

  Shell
• What part of the amniotic egg is a reservoir for nitrogenous wastes?

  Allantois
• What part of the amniotic egg prevents dehydration and mechanical injury?

  Amniotic fluid
• What part of the amniotic egg allows gaseous exchange forms placenta in mammals?

  Chorion