A diplontic animal grows through the mechanism of meiosis.
Meiosis is a type of cell division in which the parent cells divides to yield four haploid daughter cells; that is cells with half the number of chromosomes as the parents. A diploid cell is a type of cell that has two sets of chromosomes. In a diplontic life cycle, the majority of the organism's life is spent with most of the cells in the body being diploid. The only cells that have half the number of chromosomes, or are haploid, are the gametes.