Orthonectidans: Orthonectida

Orthonectidans are parasites that alternate between asexual (ay-SEK-shuh-wuhl) and sexual stages within the host animal. Asexually produced masses of young orthonectidans may develop into sexual forms. Asexual reproduction takes place without and sexual reproduction takes place with the uniting of egg and sperm for the transfer of DNA from two parents. During mating male orthonectidans make brief contact with females and release sperm. Fertilization (FUR-teh-lih-zay-shun), the joining of egg and sperm to start development, takes place inside the female. Embryos form about twenty-two hours later. When the embryos are fully developed, the female ruptures and dies, releasing larvae (LAR-vee) that disperse and enter a new host. Larvae are animals in an early stage that change form before becoming adults.