As human beings we are accustomed to thinking of males having one penis and two testes and females having one vagina and two ovaries (though there are exceptions to this among men and women). However, a number of animals generally quite primitive species - boast a greater quantity of sex organs. For instance the medusa of the water-living obelia, which looks like a tiny bell-shaped piece of clear jelly, has no less than four testes in the male and four ovaries in the female. Eggs and sperm are simply shed into the sea-water where fertilisation takes place. But the most prolific number of sex organs can be found in our friend the tapeworm. It has been suggested that the tapeworm is "nothing but a bag of reproductive organs". In every segment there are bunches of testes and bunches of ovaries - which means that an individual adult can finish up with hundreds of gonads.