Debby Wharf, age 11, of Falmouth, Maine her question:
Are algae plants or animals?
The earth’s animals can travel under their own power and in most cases we can depend upon the plants to stay rooted to the spot. Plants manufacture their own foods from simple chemicals, while animals feed on foods made directly or indirectly by the plant world. It is true that scientists class some living things in between the plant and animal king¬doms. But all of them agree that the algae belong to the plant world.
Nobody knows exactly when the first living things arrived on the planet earth. But they must have been plant type organisms, able to use the energy of sunlight to manufacture their own foods from water and dissolved chemicals. In this case, they must have been plants of some sort, and most scientists agree that at least some of the earth’s first living things were alga type plants.
Life, we are told, began in the ancient freshwater seas, more than a billion years ago. It is logical to assume that the first living things were single celled water plants. Each of these tiny, alga type plants could manufacture its own food from carbon dioxide and other chemicals dissolved in the water.
We do not know exactly what they were like, for the fragile midgets left no fossil remains. But it seems more than likely that their descend¬ants became the thousands of different algae that teen in the modern world. They range in size from single celled species to giant kelps, with streamers that trail 60 feet long. Alga plants thrive in salty seas, in freshwater ponds, streams and marshes, in snows and in soils where there is enough moisture for them.
Though they are true plants, they have no true roots or stems. The giant kelps anchor themselves to the seabed with simple holdfasts. Smaller alga and other seaweeds are wafted around the world by the heaving oceans. Most of the floaters are single celled algae. A row of 2,500 of these midgets may measure no more than an inch.
Having no roots, algae need more moisture than other plants. But since they live on such a moist, watery planet, there are plenty of places for them to thrive. What’s more, they have easier ways to multiply than the more advanced land plants. Even in the large algae, each cell is capable of carrying on the business of multiply and manufacturing food. Algae such as pond scum form spores with tough coats. If the pond dries up, these spores can survive until the moisture returns. The single celled types can multiply by dividing.
This is what happens when the clean water in a fish bowl becomes clouded with green. A few invisibly small green algae got into the water. Each multiplied by dividing into a pair of twins—again and again. In perhaps a few sunny hours, there are enough of these mini plants to cloud the water with their greenery.
Algae such as pond scum form spores with tough coats. If the pond dries up, these spores can survive until the moisture returns. The single celled types can multiply by dividing. This is what happens when the clean water in a fish bowl becomes clouded with green. A few invisibly small green algae got into the water. Each multiplied by dividing into a pair of twins—again and again. In perhaps a few sunny hours, there are enough of these mini plants to cloud the water with their greenery.