Summary Animal Reproduction

Sexual Reproduction of animals (non-human
reproduction)

In Sexual reproduction a new individual is formed by the fusion of
two gametes from two parents – gametes are haploid cells which fuse
to create a diploid cell.

 Gametes are the egg cells and the sperm cells and are produced
in the gonads by meiosis
 Fertilization is the process in which gametes fuse together, the
haploid egg fuses with the haploid sperm and a diploid cell is
formed
 Diploid cell is known as the Zygote

External fertilization
- done in an environment where the egg won’t desiccate and
sperm can swim to the egg
- common in aquatic organisms
- egg and sperm are released simultaneously into the water
(reproduction synchrony or synchronous spawning)
- ideal means of reproduction for sessile creatures

Advantages of External Fertilisation
 no additional energy spent on formation of an egg or parental
care
 male doesn’t need copulatory organ

Disadvantages of External Fertilisation
 wasteful – many eggs and sperm are created
 chanceful – never any certainty in fertlisation taking place
 unprotected
 susceptible to environmental conditions

Internal Fertilisation
- requires the male to insert his copulatory organ into the
female’s vagina
- often involves courtship
- avoids desiccation, wastage and chance issues
- good parental care
- good survival rates