We know from high school biology that those green things with leaves that we see just about anywhere are living things called plants that have the unique ability to photosynthesize. Algae, those leafy things we see underwater or on the surface of the sea in the occurrence of algal blooms, also contain pigments that allow them to be able to photosynthesize, too.
So does this mean that algae are also plants?
How Are Algae Different From Plants?
1. Algae are officially classified as protists.
Each living organism on this planet has a scientific name consisting of their genus as well as their species. However, an organism’s genus and species fall under a greater classification called kingdom.
All organisms on this planet fall under one of the five kingdoms. First, we have Kingdom Animalia, under which animals–including us, humans–fall. Next, we have Kingdom Monera, which includes Eubacteria and Archaebacteria. The third one is the Kingdom Fungi, which includes mushrooms, yeast, mildews, smuts, and mold. They are heterotrophic, which means that they cannot produce their food and thus they have to obtain it from external sources. The fourth kingdom is Kingdom Plantae which, of course, includes all plants. Lastly, we have Kingdom Protista, under which algae fall.
The fact that algae had been placed in an entirely different kingdom separate from plants alone is enough proof that they differ greatly from plants, even though they are considered “plant-like.”
Even though algae are similar to plants in certain ways, they are officially labeled as protists because they are eukaryotic, which means that they have a nucleus, however, they do not perfectly fit the requirements to be classified as animals, fungi, or plants.
2. They are not as differentiated as plants.
Algae could easily be mistaken as plants because they are often green, they may look leafy (the seaweeds we eat are algae), and they produce their food through photosynthesis. However, what led them to be classified under an entirely different kingdom is the fact that unlike plants, they are not that differentiated.
In biology, particularly when it comes to plants, differentiation is the process by which certain cells in the plant body officially earn specific roles. For example, some cells eventually become roots, some cells eventually form stems, and some cells eventually become leaves.
Algae do not exhibit such differentiation, and so while they look very much like plants, they do not have true roots, stems, and leaves.
3. Algae can either be unicellular or multicellular.
The cell is the basic unit of life. Something that is made up of cells is a living organism. These are called multicellular organisms. Examples include plants and animals, and of course, us, humans. The fact that we are made out of many different types of cells is the reason we have different body parts and systems. Algae can also exist as multicellular organisms.
However, a cell can also survive on its own because it has biological machinery inside it, just like we, human beings, have organs that allow us to live. There are many unicellular organisms. For example, a bacterium can exist alone, however, bacteria often occur in colonies. Algae can also be unicellular, however, as previously mentioned, they do not exhibit differentiation like that in plants.
To put it simply, algae can be either unicellular or multicellular, while plants are strictly multicellular.
4. There is relatively less information known about algae.
As of writing, algae are classified as protists. However, because they are different from plants and to this moment, scientists are still trying to find out as much as they can about algae, there are still a lot of things that are not known about them and so knowledgeable about them is still evolving and thus their taxonomy is still subject to change.
How Are Algae Similar with Plants?
1. They have cell walls.
The presence of a cell wall is one of the most important distinguishing characteristics if you want to distinguish animal cells from plant cells.
The cell wall is the layer between the external environment and the cellular membrane. Since it is a wall, it is mainly for providing protection, but it also has many other functions. For example, it contributes to the cell’s rigidity,
One of the reasons algae are plant-like is the fact that they have cell walls.
2. They have double-membraned chloroplasts.
The cells of all organisms contain organelles. These organelles can be somewhat compared to the vital organs that we, human beings, possess. Each of them has a unique and important function that is essential to the survival of the cell. One of these organelles is called the chloroplast.
Algae, especially green algae, have chloroplasts. Chloroplasts are disk-shaped organelles that contain chlorophyll, the green pigment that is a highly essential ingredient in photosynthesis. Chloroplasts, with the help of the green pigment they contain, are the ones responsible for capturing sunlight so that it can be used to produce glucose and oxygen from carbon dioxide and water through the process of photosynthesis.
3. Both of them produce their food via photosynthesis.
Photosynthesis is the way by which plants make their food. Since this makes them sort of “independent,” they are considered autotrophic.
During this biological process, plants use carbon dioxide and water to produce glucose with the help of sunlight. Glucose is essential for all living organisms as a source of fuel to survive. Oxygen is a byproduct of photosynthesis and we, humans, can breathe in the oxygen that is made by plants.
Most of us think algae are plants, but the truth is, they are not. They may look leafy but guess what, the leaves you see are not considered true leaves. Even the seaweeds that we love to eat in Asian restaurants are not leaves. They are algae.
And algae are different from plants because the cells that comprise algae are not able to differentiate into different plant parts like stems, roots, and leaves.
Algae and plants have other differences, but that is probably the most important one. So now, if ever you go for a swim at the beach and someone asks you what those green things that can be seen underwater are, you know the answer.