Red algae (FIW)

Red algae becomes the new filler of the corals' ecological niche in such areas as the Shallow Seas, 100 million AD, in the documentary The Future is Wild.

The dominant reef-building organisms of previous times were corals. Algae cells lived symbiotically with the coral, supplying oxygen and carbohydrates used in the production of calcium. With the recent glacial period, in 5 million AD, came massive climatic disruption. The seas filled with mud, depriving the algae of the sunlight they needed for survival. Without the algae and the essential nutrients they provided, the corals also became extinct some time later. Now, tens of millions of years later, there are large areas of warm, shallow water and conditions are right for reefs to develop once more. This time, the reefs are formed not from coral, but from a prolific species of red algae.

Red algae, dating back to the Ectasian period in the Mesoproterozoic era, 1.2 billion BC, were not always prolific. Their reproductive cells cannot swim, so the algae's fertilization technique was a matter of releasing millions of gametes into the water and relying on favorable currents to carry them to the female organs. Now, 100 million AD, the red algae have evolved a sophisticated, symbiotic fertilization process by teaming up with a reef-dwelling animal, like a young reef glider. The algae offers up a protein meal and, as the animal moves from red algae to red algae feeding on this meal, it transports the algae's sticky gametes. This new species of red algae produces fewer gametes and yet enjoys a much better fertilization rate. With such reproductive efficiency, the red algae have built up a successful reef system.

Shafts of sunlight will slant through the clear water of the Shallow Seas, penetrating as far as the jagged spikes of the algal reefs which form much of the seabed. Here and there, cuplike shapes sprout from the red surface of the reef. Swimming animals dart among the reefs and algal flowers. In the base of the cups, the algae produce deposits of protein and carbohydrates that lure in vector animals.