Question

Why are dinoflagellates called fire algae? Give an example.

Answer 1

Hint: The dinoflagellates are single celled eukaryotes that are placed under the Kingdom Protista. They are called dinoflagellates because they have two unequal flagella. One of the flagella lies transversely while the other lies longitudinally. They have a cell wall made up of many layers of cellulose plates.

Complete answer:
The dinoflagellates are known for having features similar to both plants and animals. The cell of dinoflagellates contains membrane bound organelles such as mitochondria, golgi bodies, endoplasmic reticulum etc. The dinoflagellates are mostly found in marine environments. However, some can be found in freshwater. They are photosynthetic and contain pigments such as chlorophyll A, chlorophyll C, carotenoids and xanthophyll. The flagella helps them in movement. The reproduction in these organisms depends upon the sea surface temperature, salinity and availability of nutrients.
The dinoflagellates appear in different colors like yellow, green, red and brown because of the main pigments present in them. The 18 genera of dinoflagellates have bioluminescent properties. The luciferin pigment present in the dinoflagellates makes them bioluminescent. This pigment is activated by the catalytic enzyme called luciferase. This results in production of light even in the absence of heat. Hence, dinoflagellates are called fire algae. However, the light production does not occur by pigment itself, it is caused by the enzymatic reactions of the pigment. These enzymatic reactions are pH dependent. A drop in pH level would affect the enzyme’s structure.
The bioluminescent property of these organisms helps them in two ways. The first is, it protects them from predators. The second is, it helps these organisms to communicate with each other.
Gonyaulax is an example of dinoflagellate.

Note:
The red tides that appear in marine environments are caused by the rapid multiplication of red dinoflagellates. They form blooms in water bodies. The blooms release toxins which harm marine organisms. Karenia brevis is an example of red dinoflagellates.