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Biology LibreTexts

12.3: Vertebrate Reproduction

Does the embryo develop in the mother or in an egg?

Is the egg within the mother or not? Vertebrate reproduction occurs by one of three methods. These bird eggs demonstrate one of three types of vertebrate reproduction.

Vertebrate Reproduction

Vertebrates reproduce sexually, and almost all of them have separate male and female sexes. Recall that sexual reproduction is the joining of gametes during fertilization, producing genetically variable offspring. Generally, aquatic species have external fertilization, whereas terrestrial species have internal fertilization. Can you think of a reason why aquatic and terrestrial vertebrates differ in this way?

Vertebrates have one of the following three reproductive strategies: ovipary, ovovivipary, or vivipary.

  • Ovipary refers to the development of an embryo within an egg outside the mother’s body. This occurs in most amphibians and reptiles and in all birds.
  • Ovovivipary refers to the development of an embryo inside an egg within the mother’s body until it hatches. The mother provides no nourishment to the developing embryo inside the egg. This occurs in some species of fish and reptiles.
  • Vivipary refers to the development and nourishment of an embryo within the mother’s body. Birth may be followed by a period of parental care of the offspring. This reproductive strategy occurs in almost all mammals.

Kangaroo with offspring

What type of reproduction occurs in kangaroos?


  • Vertebrates reproduce sexually, and almost all have separate male and female sexes.
  • Aquatic species generally have external fertilization, whereas terrestrial species usually have internal fertilization.
  • Vertebrates have one of three reproductive strategies, known as ovipary, ovovivipary, or vivipary.


  1. Define ovipary, ovovivipary, and vivipary.
  2. Which vertebrates use each type of reproductive strategy?