Red Algae

1. Red Algae Pigment, depth, food and products

2. Pigment • The red color of the algae comes from the presence of phycobilin or phycoerythin- a pigment. • This pigment absorbs blue light, so red is reflected back. • Because blue light penetrates water to greater depths than other light, the red algae can photosynthesize deeper in water than other algae.

3. Depth • The survival depth of algae varies depending on latitude, temperature, salinity, currents, etc… • Red, green, and brown algae live at different depths where different colors of light can reach them. • Because blue light can travel farthest in water, red algae can survive in transparent, fresh water for up to about 180 meters. • In the Atlantic ocean, where the water is cloudy, they only live in 30 meter depth.

4. Food • Algae is an important component of diets around the world, especially because it is very easy to grow. • Irish moss, another type of red algae is a major source of carrageenan, a thickener used in place of animal-based products (such as gelatin which comes from animal bones). It is used in many things like ice cream and non-dairy frozen desserts. • In the Caribbean, the red algae is used directly to make a drink with sweet and condensed milk and flavoring over ice.

5. Food continued… • Red algae are eaten by herbivorous animals such as fish, crustaceans, worms, gastropods. • They are an important part of the food chain and generate up to 60% of the food on the coral reef.

6. Products • Agar comes from the gelatinous components of the cell walls of certain red algae. • Agar is used in cosmetics, as a culture medium for laboratory microorganisms, and in various jellied desserts and soups. • They are also used, because of the high amount of nutrients and minerals, for disease prevention and to help treat various conditions in the body. It boosts immunity, but it can also protect against viruses.

7. Interesting facts • Red Tide: Red tide an algal bloom with a high concentration of a microscopic algae. • This algae can produce a toxin that affects the central nervous system of fish so that they are paralyzed and cannot breathe, and irritation of the respiratory system in humans. • Not all red tides are harmful, and simply refer to discoloration of the water (often a reddish color).

8. Algae are plants, and so they grow more with excessive nutrients, sunlight, and slow moving water. • Algal blooms occur usually in the spring or summer http://www.youtube.com/watch?v=YBk3jA5t8fQ

9. Review Questions! • What pigment does red algae absorb? • What are 3 products/uses for red Algae? • What eats red algae? • Why is algae such a major part of people’s diets? • What are some health benefits to red algae? • What are the effects of Red tide?

10. Review Question Answers • Blue • Food, Agar (scientific applications), Carrageenan (used in ice cream, toothpaste, milkshakes...) • Herbivorous animals (fish, crustaceans, worms, gastropods) • Very nutritious and easy to grow • Disease prevention, boosts immune system, protection against viruses • It affects the respiratory system of humans and paralyzes fish so they cannot breathe, and drown.