Laminariacea Family of Kelp

Two Kelp of the Laminariacea Family can be found in this website:

Phylogeny: The Laminariaceae Family of Kelp is a brown algae in the Kingdom Chromista. Chromists are photosynthesizing organisms that used to be known as Protista. This diverse kingdom includes brown algae, diatoms, mildew, and malarial parasites. The Laminariaceae Family is in the phylum Ochrophyta. Ochraphytes are multicellular brown-pigmented algae, characterized by their flagella and chloroplast structure. The class Phaeophyceae is one of seventeen classes in this phylum. Class Phaeophyceae consists of four subclasses and twenty orders. The Laminariacea Family is located in the subclass Fucophycidae and in the order Laminariales. The Laminariaceae Family is comprised of fourteen genera and sixty-nine species. The name Laminariaceae comes from the Latin word lamina, meaning “thin sheet or leaf” and refers to the leaves (lamina) of these algae.

Morphology: Kelp of the Laminariaceae Family have a thallus (body of the organism) that is comprised of three organs: the holdfast, the stipe, and the lamina. The thallus is held to the bottom substrate by a root-like holdfast. The intertwined and branched haptera tissue of the holdfast anchors the plant, but does not gather nutrients or water like a root does. The stem-like stipes provide structure and primarily connect the holdfast to the laminae.  The leaf-like laminae are long and blade-like. Kelp uses chlorophyll A and chlorophyll C for photosynthesis. The brown to amber color comes primarily from these chemicals and fucoxanthin. Some species in this family only reach 2 m (6.5 feet) in length, while others reach 45 m (148 feet). In some species a single lamina can reach 3 m (10 feet) in length.

Habitat and Distribution: Kelp is found attached to rocks or other hard substrates. Because it requires sunlight for photosynthesis it is usually found in fairly shallow water. It grows in the intertidal zone and to depths of 78 m (256 feet). Kelp is found worldwide in polar to tropical seas. Two species from Laminariaceae Family are found in Mexican waters.

Reproduction: Kelp alternates between an asexual sporophyte generation and a sexual gametophyte generation. Adult sporophytes reproduce asexually through the production of spores, which produce gametophytes.  Gametophytes are very small and produce either male (sperm) or female (eggs) gametes. The gametophytes release their gametes into the water. The eggs release a pheromone which attracts the motile sperm. The sperm swims to the egg and fertilization occurs and forms a zygote, which grows into a juvenile sporophyte. The sporophyte matures and completes the cycle.

Ecosystem Roles: Kelp is a critical part of many marine ecosystems. It provides food, structure, and camouflage for hundreds of species of crustaceans, fish, mollusks, and other invertebrates.