Fertilisation is the fusion of a haploid male gamete with a haploid female gamete to form a diploid zygote. In internal fertilisation, the gametes fuse inside the body of the female. The male places sperm directly into the female reproductive tract, usually during mating (copulation). Mammals, birds, reptiles and insects all use internal fertilisation.Internal fertilisation has several advantages:
• the gametes are protected from drying out, so fertilisation does not depend on external water for sperm to swim in. This allowed animals to reproduce on dry land.
• sperm are released close to the egg, so the chance of fertilisation is high and far fewer gametes need to be produced.
• gametes and the zygote are protected from predators and from being washed away.After internal fertilisation, the embryo may develop inside the mother (as in most mammals) or be laid inside a protective shelled egg (as in birds and reptiles), giving the offspring a better chance of survival.The main disadvantages are that a mate must be found, courtship and mating use time and energy, and fewer offspring are usually produced.Flowering plants also have internal fertilisation. The male gametes never travel through water: they are carried inside a pollen tube that grows through the tissues of the carpel to the ovule, where fertilisation happens.
• the gametes are protected from drying out, so fertilisation does not depend on external water for sperm to swim in. This allowed animals to reproduce on dry land.
• sperm are released close to the egg, so the chance of fertilisation is high and far fewer gametes need to be produced.
• gametes and the zygote are protected from predators and from being washed away.After internal fertilisation, the embryo may develop inside the mother (as in most mammals) or be laid inside a protective shelled egg (as in birds and reptiles), giving the offspring a better chance of survival.The main disadvantages are that a mate must be found, courtship and mating use time and energy, and fewer offspring are usually produced.Flowering plants also have internal fertilisation. The male gametes never travel through water: they are carried inside a pollen tube that grows through the tissues of the carpel to the ovule, where fertilisation happens.