The chlorophyll a, chlorophyll b and other photosynthetic pigments aid algae to absorb and harness sunlight into chemical energy, which is necessary for algae to live.

See explanation.

**Euglonophytes** are plantlike protists that contain two flagella, chloroplasts, and eyespot. These species do not have a cell wall, rather it has an intricate cell membrane called *pellicle* that helps this organism to move and swim.

**Chrysophytes** are plantlike protists that can be distinguished through their gold/brown colored chloroplasts. The cell wall of these species is made up of pectin rather than cellulose.

**Diatoms** are the most abundant protists. They produce a thin, intricate, delicate cell wall that contains silicon (Si). The walls of these organisms look like Petri dishes and they have fine patterns and lines that create a beautiful glass-like appearance.

**Dinoflagellates** are group photosynthetic and heterotrophic protists. They have thick plates that cover the organism and a cellulose cell wall to protect the cell. These organisms reproduce through binary fission.

Unicellular plant-like protists make their own organic food source by converting sunlight into chemical energy. Animal-like protists get their food by capturing and eating other organisms.

**Unicellular algae** are the main food source for other organisms. Since they are at the bottom of the food web, many organisms cannot live without them. In addition, they live symbiotically, and peacefully with other organisms.

Since algae need nitrogen-containing compounds to grow and multiply, you can significantly **reduce the amount of sewage entering the water** and **stop using artificial fertilizers** that are full of nitrogen substance.

The **dinoflagellates** that produce red tides also produce strong toxins. Filter-feeding shellfish that consume these organisms become filled with toxins. That toxin becomes concentrated in other organisms when they eat those toxic shellfish. This disrupts the ecosystem because the food chain is disrupted.