Algae is an organism. Just as there are many types of organisms in nature, there are various kinds of algae, as well. Although many forms of algae share common traits such as the fact they all have trace DNA, the characteristics you might use to distinguish between the types are subtle, but nonetheless discernible.
One of the two characteristics you may use to distinguish red algae from brown is its pigmentation. Also called "phycoerythrin," the pigment in red algae only typically grows in warmer water. It is another characteristic you may use to tell the two apart. This is in stark contrast to brown algae, which generally grows in colder water. Red algae is biologically categorized in the "Rhydophyta" phylum while brown algae falls under "Phaeophyta." Red algae is also called "Coralline seaweed," in some regions of the world.
Brown algae, otherwise known as "phaeophyceae," is distinguishable from red algae in that it looks like a common variety of seaweed. It contains fucoxanthin, a chemical found in many "sea vegetables." Although the red algae may grow more readily in deeper "tropical" waters, brown algae is longer and more flexible. It is also a bit less sensitive to cold temperatures than red algae. Common names for brown algae include: Neptune's necklace, Leather kelp, Strap weed and globe algae.
Red algae is usually much harder on the surface than brown algae. It often develops from a chemical compound called "calcium carbonate," which allows it to adhere to other hard surfaces such as rocks or reefs. The scientific name for red algae is "Kallymenia perforata." It also is the only form of algae that contains "flagella," cellular structures that look a lot like hair.
You might be able to distinguish brown and red algae by first considering from where they originate. Red algae, for example, live in various locales worldwide, but mainly form in tropical, coastal water landscapes. Brown algae may live in both cold or waters, but typically do not develop at extremely large depths. Red algae may grow as deep as approximately "200 meters," which equates to approximately 656 feet.
- Lenntech: Algae Description and Types
- University of California Museum of Paleontology: University of Berkeley; Introduction to the Rhodophyta
- Marine Education Society of Australasia (MESA): Algae; Life on Australian Seashores
- Stanford University: Phaeophycea
- Health Food Emporium: Fucoxanthin Explained
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