Kelp vs. Seaweed

Main Difference

The main difference between Kelp and Seaweed is that the Kelp is a order of brown algae and Seaweed is a various types of algae

• Kelp

  Kelps are large brown algae seaweeds that make up the order Laminariales. There are about 30 different genera. Despite its appearance, kelp is not a plant; it is a heterokont.

  Kelp grows in “underwater forests” (kelp forests) in shallow oceans, and is thought to have appeared in the Miocene, 5 to 23 million years ago. The organisms require nutrient-rich water with temperatures between 6 and 14 °C (43 and 57 °F). They are known for their high growth rate—the genera Macrocystis and Nereocystis can grow as fast as half a metre a day, ultimately reaching 30 to 80 metres (100 to 260 ft).Through the 19th century, the word “kelp” was closely associated with seaweeds that could be burned to obtain soda ash (primarily sodium carbonate). The seaweeds used included species from both the orders Laminariales and Fucales. The word “kelp” was also used directly to refer to these processed ashes.

• Seaweed

  Seaweed, or macroalgae, refers to several species of macroscopic, multicellular, marine algae. The term includes some types of Rhodophyta (red), Phaeophyta (brown) and Chlorophyta (green) macroalgae. Seaweed species such as kelps provide essential nursery habitat for fisheries and other marine species and thus protect food sources; other species, such as planktonic algae, play a vital role in capturing carbon, producing up to 90 percent of earth’s oxygen. Understanding these roles offers principles for conservation and sustainable use. Mechanical dredging of kelp, for instance, destroys the resource and dependent fisheries.

  Seaweed are a source of biologically active compounds including proteins and polysaccharides with promising uses in nutrition, biomedicine, bioremediation and other uses.

• Seaweed (noun)

  large algae growing in the sea or on rocks below the high-water mark

  “seaweed glistened on the rocks”

  “seaweeds abound on most shores”