Phillum heterokonts: The Sargasso Sea and the forests of Kelp.
The Sargasso Sea was known long before the arrival of Columbus. Romans, Greeks and Phoenicians were already talking about a sea of vegetation dangerous for boats. Probably, it was the origin of medieval legends and myths of the island Antilia, very popular in the fifteenth-century
It is a calm sea for the absence of winds, located in the northern Atlantic Ocean, near the coast of Cuba. Is bounded by three currents of the North Atlantic (north), the Equator (south) and Gulf (west) and not by the waterfront. These currents find the surface waters are warm and move slowly clockwise as opposed to deeper, colder and denser. The temperature stratification, prevents water from mixing.
The Sargassum is a genus of brown planktonic macroalgae (Sargassum, Order Fucales). Communities form dense tangled meadows that form the basis of a closed ecosystem in dynamic equilibrium in an unfavorable area. They have adapted to pelagic life, living without being attached to rocks, partly thanks to its air-filled vesicles.
Many organisms live among them, like fish Histrio histrio or eels (though only going to spawn) and above them, like other smaller algae, hydroids coelenterates (like corals), tube worms and bryozoans.
The kelp forests are composed of laminated (Order Laminariales) brown algae attached to rocky substrate. They are a hotspot due to hold a large amount of wildlife.
The International Union for Conservation of Nature (IUCN), suggests that kelp forests can store as much as 60 million tons of carbon that could contribute to oceanic acidification.
Human beings use them in their own interest, its alginate as a thickener, or their ashes, rich in iodine to manufacture fertilizer, soap and glass. Also has a rapid growth and releases methane when it decomposes, suitable for be a potential source of renewable energy.