Fieldtrips and Fieldtrip Classes

Phylum Rhodophyta: The Red Macroalgae

There are more species of red macroalgae than there are of green and brown macroalgae combined. Most species are red or pink in color, the result of red pigments (called phycobilins) that mask the green color of the chlorophyll in their cells. Most red macroalgae are marine and live in shallow-water environments.

The commercially important emulsifier carrageenan and the thickener agar are both obtained from red macroalgae. Carrageenan is responsible for giving body to dairy products (among other things) and agar forms jellies that protect canned meats.

The structure of red macroalgae often varies by the energy of the environment—in rocky intertidal areas, the algae are often low and encrusting, whereas in deeper waters, the algae are more massive, with long branching blades. Coralline red algae are important because they secrete calcium carbonate within their cell walls for protection and support. They may be encrusting or upright and branching. Coralline red algae contribute to the formation of reefs and (after they die) to sandy bottoms.

Click on the links below to learn more about different types of red macroalage that are found in the intertidal of the Gulf of California. To go back to the Gallery of Marine Life, click here.

To take a practice quiz on the Phylum Rhodophyta, click here.