Mating and Fertilisation

In all animals sperms are motile and have to move and seek the eggs to fertilise them. For this an aqueous environment is necessary. This need of a liquid medium has led to two basic mating patterns.

1. External fertilisation - mating partners come in close proximity in water and concurrently shed their eggs and sperms in water.

2 Internal fertilisation - mating partners come into physical contact and copulate, in which the male transfers the sperms directly into the reproductive ducts of the female. The ova coming down the ducts obtain fertilized. Internal fertilisation is characteristic of terrestrial animals, but as well occurs in several aquatic forms. Internal fertilisation usually leads to development of an intromittent organ or penis in the male partner. A range of such copulatory organs are found in non-chordates, such as like dates there are spermathecae for storing sperms received during mating. As the eggs pass down the ducts sperms are released from the spermathaca to feitilise them. Honey bee queen mates just one time when it receives enough sperms to fertilise the many thousands of eggs she is going to lay in 4-5 years of reproductive life.