Pigments
The red color in the algae is primarily due to phycoblin pigments that absorb green, yellow, red and blue light that penetrate to greater depths. A lower intensity of light stimulates the algae to produce more red pigment, while a greater intensity causes breakdown of the pigment.
Types
Some of the better-known red algae are consumed as food, according to Professor Michael Guiry at the National University of Ireland. These include nori or laver, which is grown by aquaculture for making sushi; dulse, which is consumed in the United Kingdom; and carageen moss, which is the source for carageenan, commonly used as a thickener in food products.
Medicinal Uses
The red algae Callophycus serratus has demonstrated antibacterial, antiviral and antitumor activities, which are being further investigated along with other species of red algae, according to ScienceDaily.com. This species lives along the coast of Fiji.