Difference between external and internal fertilization in animals

in external fertilization fusion of the male and female gametes takes place outside the body of the female e.g. amphibians and fish while in internal fertilization union of gametes occurs inside the body of the female




advantages and disadvantages of external fertilization

Advantages

  • large numbers produced therefore many offspring per breeding season
  • female does not suffer gestation stress
  • mother does not need to care for the young except in a few species
  • the surviving individuals are highly selected for better survival

Disadvantages




  • many predators surround the eggs before and after fertilization
  • fewer chances of fertilization/a lot of gametes wasted
  • embryo development at mercy of environment
  • large numbers of female gametes are required therefore female gets much exhausted

advantages and disadvantages of internal fertilization

Disadvantages

  • number of gametes fewer hence less number of offspring
  • less adapted for sudden change of environment after birth
  • in mammals females suffer gestation stress




Advantages

  • more chances of fertilization
  • fewer predators of oval/fertilized egg protected in females body
  • stable internal environment
  • fewer gametes required
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