CHAPTER THREE
REPRODUCTION IN VERTEBRATES
Fertilization
External
● Sperm fertilizes egg outside of body
● Contact is unnecessary
● Requires water to prevent gametes from drying out and to allow for male
sperm to swim
● Mass amounts of semen needs to be released as there is less chance of it
actually reaching the female eggs
● ie Frogs, starfish, trout
Internal
● Male deposits sperm into female body
● No water is required, thus allowing terrestrial life
● Less sperm produced and less energy needed
● ie Birds, mammals
REPRODUCTIVE METHODS
Classification of methods are dependent on: internal or external environment,
food source and whether the organism develops in an egg or not.
OVIPARY
● Eggs are laid
● Zygote develops outside of body
● Can be fertilised internally or externally
● Eggs are preyed on by predators
● ie Most invertebrates, a few vertebrates
REPRODUCTION IN VERTEBRATES
Fertilization
External
● Sperm fertilizes egg outside of body
● Contact is unnecessary
● Requires water to prevent gametes from drying out and to allow for male
sperm to swim
● Mass amounts of semen needs to be released as there is less chance of it
actually reaching the female eggs
● ie Frogs, starfish, trout
Internal
● Male deposits sperm into female body
● No water is required, thus allowing terrestrial life
● Less sperm produced and less energy needed
● ie Birds, mammals
REPRODUCTIVE METHODS
Classification of methods are dependent on: internal or external environment,
food source and whether the organism develops in an egg or not.
OVIPARY
● Eggs are laid
● Zygote develops outside of body
● Can be fertilised internally or externally
● Eggs are preyed on by predators
● ie Most invertebrates, a few vertebrates
