Euglenoids are primarily fresh water organisms found in stagnant water. A distinctive feature of euglenoids is that instead of a cell wall, they possess a protein-rich layer called pellicle which makes their body flexible.

They have two flagella – a short and a long one. Euglenoids exhibit unique nutritional behaviour as they are photosynthetic in the presence of sunlight, but when deprived of sunlight, they behave like heterotrophs by predating on other smaller organisms.

Interestingly, the pigments of euglenoids are identical to those present in higher plants. Euglena is a common example of euglenoids.