I.e in presence of sunlight euglena undergo photosynthesis and act as autotroph....but in absence of sunlight , they. behave like heterotrophs by predating on other smaller organisms.

Photosynthetic and Saprophytic Organisms

Photosynthesis is the process by which plants and some bacteria convert light energy into chemical energy to produce organic compounds such as glucose. Saprophytic organisms, on the other hand, are those that obtain nutrients by breaking down dead or decaying organic matter.

Some organisms are capable of both photosynthesis and saprophytism. One such organism is Euglena.

Euglena

Euglena is a unicellular organism that belongs to the kingdom Protista. It is a mixotroph, which means that it can obtain nutrients from both organic and inorganic sources. Euglena has a unique feature that allows it to switch between photosynthesis and saprophytism depending on the availability of light and organic matter.

Photosynthesis in Euglena

Euglena has chloroplasts, which are responsible for photosynthesis. Chloroplasts contain pigments such as chlorophyll and carotenoids that absorb light energy. Euglena can synthesize its own food by using the energy obtained from light to convert carbon dioxide and water into glucose and oxygen.

Saprophytism in Euglena

When light is not available or when Euglena is in the presence of decaying organic matter, it switches to saprophytism. Euglena can break down the organic matter using enzymes secreted by its cells. The nutrients obtained from the breakdown of organic matter are then used to sustain the cellular processes of Euglena.

Conclusion

Euglena is a unique organism that can perform both photosynthesis and saprophytism depending on the availability of light and organic matter. This ability makes Euglena a versatile organism that can survive in a variety of environments.