feed on the blades (leaves) of the laminaria. Other organisms, such as sea urchins, feed on the holdfasts, which can kill the algae. Red sea urchins, found on the North America Pacific Coast, can decimate kelp, including Laminaria, if the urchins are not managed by sea otters. Species such as Coelopa pilipes feed and lay eggs on Laminaria when it is washed up on beaches. Life cycle Laminaria expresses a haplo-diplophasic life history, in which it alternates from a macroscopic thallic sporophyte structure, consisting of the holdfast, a stipe, and the blades, to a filamentous, microscopic gametophyte. The sporophyte structure of laminaria can grow to , which is large in comparison to other algae, but still smaller than the giant kelps such as Macrocystis and Nereocystis, which can grow up to . On the other hand, the gametophyte structure is no more than a few millimeters in length. In opposition to the gametophyte phase, which only consists of one type of tissue, the more complex sporophyte phase is made up of different types of tissue. One of these tissues includes a sieve-like element which translocates photoassimilates. These structures are very similar to mesophyll cells found in higher plant leaves. Uses Medical A laminaria stick may be used to slowly dilate the cervix to induce labor and delivery, or for surgical procedures including abortions or to facilitate the placement of an intrauterine device. The stick is made up of a bundle of dried and compressed laminaria that expands as water is absorbed. Laminaria is a source of the relatively rare element, iodine, which is commonly used to promote thyroid health. Certain carbohydrates such as mannitol, laminarin, and alginate can be extracted from laminaria. Mannitol is used to decrease high intraocular pressure, and to lower excessive intracranial pressure. Laminarin has two forms, soluble and insoluble. The soluble form of Laminarin has high antitumor activity, can be used in the treatment of antibiotic-resistant nosocomial infections, can aid in normalizing enteric metabolism, helps to improve enzymatic processes of the intestine and does not possess antigenic or pyrogenic properties. Laminarin continues to be of active study in today's medical field. Food Various species of Laminaria have been used for food purposes since ancient times wherever humans have encountered them. Typically, the prepared parts, usually the blade, are consumed either immediately after boiling in broth or water, or consumed after drying. The greater proportion of commercial