Sargassum © DJ Zemenick


While those unfamiliar with aquatic plants may interchange the names, seaweed is different than seagrass. Both use light to photosynthesize and produce food and are in the Plant kingdom. However, seagrasses are flowering plants with roots, stems, and vascular systems that move nutrients and water throughout the plant. Seaweed is nonvascular, absorbing water and nutrients directly through its leaves, and consists of a large group of algae, usually differentiated by their color.



Most of the substance referred to as seaweed is actually a Brown Algae known as Sargassum. Sargassum is characterized by its bushy, highly-branched stem with numerous leafy blades and berry-like, gas-filled structures that aid its buoyancy. It tends to accumulate into large mats that drift through the water in response to wind and currents These drifting Sargassum mats create a pelagic habitat that attracts many marine animals. Many of these organisms are adapted to life within the Sargassum, reaching full growth at miniature sizes and camouflaged in shape and color to blend in. These very specialized fauna include the Sargassum fish, the Sargassum shrimp, and the Sargassum crab.


Young sea turtle hatchlings will spend their early years feeding and resting within the relative safety of Sargassum mats. When buoyancy is lost and the Sargassum sinks, it provides an important source of food for bottom-dwelling creatures. If washed ashore, many of the animals abandon the Sargassum or risk drying out and dying.



Green Algae are the most diverse group of algae, with more than 7,000 species growing in a variety of habitats. Like vascular plants, Green Algae use chlorophyll to transform light energy into sugars. June grass is a common Green Algae found in our coastal waters. It often washes up on beaches as the Gulf heats up in June, but it can be found throughout the summer. Some beachgoers may find it unappealing as it breaks down on the shoreline, but it does not contain toxins and is not harmful.


Approximately 6,000 species of Red Algae exist on earth, most in marine environments. Not all Red Algae appear red but all contain red pigment, which allows it to absorb low levels of light and therefore live at greater depths than other algae.


Green Algae

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