is euglena a plant or an animal?

Neither. Euglena belongs to kingdom Protista since they are unicellular eukaryotes.

 

Euglena shows certain features of both plant and animal. They can make their own food like a plant, but they can also eat other things, like an animal. They can also swim and move. They are included in Protista Kingdom with other microscopic organisms, such as Amoeba and Paramoecium.