Laminaria Life Cycle

Laminaria is a genus of 31 species of brown algae (Phaeophyceae), all sharing the common name "kelp". This economically important genus is characterized by long, leathery laminae and relatively large size.Some species are referred to by the common names "Devil's apron" (due to their shape) and/or "sea colander" (due to the perforations present on the lamina). Laminaria has an alternation of generations in its life cycle, involving a large sporophyte and a microscopic gametophyte . The sporophyte is harvested as seaweed. The mature sporophyte form the reproductive organs called sori; these are found on the underside of the leaves and produce the motile zoospores that germinate into the gametophyte. Laminaria Life Cycle: The sporophyte is usually found in water just below the line of lowest tides. They usually attach by branching holdfasts to rocks. At the end of the main growing season, sporangia develops from the surface cells. The sporangia, in turn, undergo meiosis to produce two types of zoospores. Although the two zoospores appear identical, one of them will develop into the male gametophytes and the other into the female gametophyte. The gametophytes are short, branched filaments that grow on the surface of subtidal rocks. The female gametophytes produce eggs, which remain attached to the gametophyte while the male gametophytes produce sperm. The sperm is released and is attracted to the female gametophyte by a species-specific chemical signal secreted by the eggs. The sperm fertilizes the egg. The zygotes grow into sporophytes, which remain attached to the disintegrating female gametophyte and begin the cycle again.