Eudorina - a colonial algae

Eudorina is a genus of green freshwater algae. Each eudorina are multicellular colonies consisting of 16, 32 or even 64 individual cells held together by a gelatinous substance made of sugary proteins, or glycoproteins to be a bit more scientific. The individual cells in a colony are not much larger than our blood cells, and the entire colony is about the same size as the width of a human hair. The green color is due to the presence of large chloroplasts inside each cell used for energy production through photosynthesis.

Note the gelatinous transparent matrix surrounding each colony.

Each cell in a colony is equipped with two extremely thin whip-like structures called flagella, which are used for movement. All of the flagella in a colony beat in a coordinated and synchronized manner which allow the colony to move in a specific direction, and not just tumble randomly around.

Focus on the incredibly thin flagella protruding from each cell

The cells in the colonies are also equipped with small red eyespots called stigma. These are a collection of light sensitive proteins enabling the algae to sense light intensity and direction. Being able to sense light allows the colony to move towards the optimal place for photosynthesis. Even though eudorina colonies are spherical and symmetrical, the do have a front and a back end. The eyespots in the front end are substantially larger than the ones in the back end. This means that eudorina has a preferred direction of movement.

Note the red eyespots