Randy Hedrick, age 9, of High Point, North Carolina, for his question:
How does algae form?
Algae are living plants and all living things mast come from parents. The ancestors of the algae were the earth's first living things. So we can expect them to be more simplified than the plants that came later. For example, they have no veins, roots or stems and they need more moisture than other plants. But Algae are more successful at multiplying themselves. This is because most of them have more than one way to form more algae
If you count up all the different plants, chances are you would forget the algae.
True, they seem to be rather unimportant when compared with redwoods and roses. But there are thousands of different algae and they happen to be some of the most important plants in the whole world. They thrive in the seas, in rivers and ponds, in the soil, and even in the snow and wherever else there is enough moisture for them. These teeming algae provide food for fishes and other creatures. They also pour tons of oxygen into the air for us to breathe.
The various algae include floating seaweeds and giant kelp, with trailing streamers maybe 60 feet long. Pond scum and frog spittle are also algae. But most types are so small that it takes about 2,500 of them to measure one inch. We need a microscope to see one of these. But we can see them in the fish bowl when zillions of them cloud the water with foggy green mist.
Most likely, a few of these fish bowl algae were there, too small to be seen, on something in the aquarium. Chances are they are algae that need only one parent to get started. They multiply by dividing. Each tiny plant cell divides itself to form two identical daughter cells. The two daughters divide and form four cells, these form eight, then sixteen, thirty two and so on. In a few sunny hours, the numbers may double every few minutes. Soon they form a cloudy mist in the water.
Some algae form spores inside their tiny cells. The spores of many fresh water algae are encased inside hard crusts. When their ponds dry up, they can live a long time without food or water. When things improve they change into copies of their parents. Many ocean algae form spores that spend a while as tiny swimmers.
Other algae have two parents. Fragments from both parents join and encase them¬selves in thick crusts. They may sleep a while or germinate right away. In some cases, each one forms four cells that are very different from the parents. Some swim around, some take a rest. Then they make another change. This time they become copies of their parents. There are many ways for the various algae to multiply. But every method requires either one or two parents for algae can only form from algae like themselves.
Algae have no veins, no roots and no woody cells. Each tiny single celled algae can do everything necessary to stay alive. Seaweeds and giant kelps are really colonies of little do it yourself cells. Each one can make its own food and form more algae. It uses sunlight to make its food from water, dissolved gases and minerals. And when times are good, algae thrive and multiply at a great rate.