English: Temporally alternating life cycles of unicellular holozoans. Life stages of the colonial choanoflagellate Salpingoeca rosetta. The asexual life cycle (on the right) includes a single-celled sessile thecate stage (adhered to the substrate), slow and fast swimming single-celled stages, and two types of clonal colonial stages (chain and rosette colonies), in which neighbouring cells are linked by intercellular bridges. Starvation triggers the S. rosetta sexual cycle (on the left), in which diploid cells (slow swimmers) undergo meiosis and recombination, and the resulting haploid cells (which can also divide asexually) mate anisogamously.