Kappaphycus alvarezii as semirefined carrageenan. "K. alvarezii" is affected by ice-ice, a disease that severely reduces its yield. This alga is an introduced species and a noxious aquatic weed in Hawaii. Kappaphycus alvarezii Kappaphycus alvarezii, the elkhorn sea moss, is a species of red algae. It is one of the most important commercial sources of carrageenans, a family of gel-forming, viscosifying polysaccharides. Farming methods affect the character of the carrageenan that can be extracted from the seaweed. This alga grows to two meters long and is green or yellow in color. It is very fast-growing, known to double its biomass in 15
Purple mixed light of two longer wavelengths. The resulting color has the same hue as pure violet; however, it has a lower saturation. One psychophysical difference between purple and violet is their appearance with an increase in luminance (apparent brightness). Violet, as it brightens, looks more and more blue. The same effect does not happen with purple. This is the result of what is known as the Bezold–Brücke shift. While the scientific definitions of violet and purple are clear, the cultural definitions are more varied. The color known in antiquity as "Tyrian purple" ranged from crimson to a deep bluish-purple, depending