Reproduction in Animals

• Importance of Reproduction

  • Ensures continuation of similar species (generation after generation)
  • Differs from life processes (nutrition, respiration, circulation) which maintain an individual

• Modes of Reproduction

  • Sexual Reproduction
    • Involves fusion of male and female gametes
    • Results in offspring combining traits of both parents
    • Found in most animals (humans, cows, dogs, birds)
  • Asexual Reproduction
    • Involves only a single parent
    • No gamete fusion
    • Found in lower organisms

• Sexual Reproduction in Animals

  • Male Reproductive Organs
    • Testes (produce male gametes / sperms)
    • Sperm ducts (transport sperms)
    • Penis (delivers sperms)
  • Female Reproductive Organs
    • Ovaries (produce female gametes / ova or eggs)
    • Oviducts / Fallopian tubes (site of fertilization)
    • Uterus (site of baby development)
  • Fertilization
    • Fusion of sperm and ovum
    • Formation of Zygote (first cell of a new individual)
    • Types:
      • Internal Fertilization: Inside female body (Humans, cows, dogs, birds)
      • External Fertilization: Outside female body in water (Frogs, fish, starfish)
  • Development of Embryo
    • Zygote divides repeatedly to form a ball of cells
    • Embryo embeds in uterus wall
    • Body parts develop, forming a Foetus
    • Viviparous Animals: Give birth to young ones (Humans, cats)
    • Oviparous Animals: Lay eggs (Birds, reptiles, amphibians)
  • Metamorphosis
    • Drastic transformation from larva to adult
    • Controlled by hormones
    • Examples: Tadpole to Frog, Caterpillar to Silkworm/Butterfly

• Asexual Reproduction in Animals

  • Budding
    • Outgrowth called a bud develops and detaches
    • Examples: Hydra, Yeast
  • Binary Fission
    • Parent cell divides into two individuals
    • Examples: Amoeba, Paramecium