All of the organisms from this videos are ciliates, unicellular organisms covered with thousands of small cilia, which are short hair-like structures they use to move and feed themselves. The green one is from the Hypotrich group and is probably an Oxytricha chlorelligera! It lives in collocation with Chlorella, a green algae, hence the name of its species. These little green algae sysnthesize sugars, a precious source of energy, by using light, water and carbon dioxide, which is a process called photosynthesis. Part of these sugars are then transferred to their ciliate host in exchange of a well suited habitat and protection against algae eaters and diverse pathogens.